Britbike forum
Posted By: splash Different spark plug readings - 03/13/21 11:02 pm
So, right spark plug is running rich af. Flat black carbon build up on right spark plug. Left plug is color of toast with very light signs of white ash on arm. After cool primed start up it will idle for a moment without any throttle. It won’t sputter at all but will suddenly stop as if the flooded prime in throat of carb ran out. Kicked over again no prime with some throttle it cranks back up. After warm up it has trouble idling when coming to a stop. It is rather nerve racking having to turn up throttle while squeezing front brake as I come to a rolling stop. This (warm) IS when it sputters to a kill unlike the cool start.

I have:
1. Cleaned and Rotated plugs still same results.
2. Cleaned carb bowl by removing bottom plug and sprayed with carb cleaner.
3. Moved air mixture screw out for leaner mixture (this is when the light ash now on left side while right is still heavy carbon).
4. Sprayed carb cleaner around all carb gaskets looking for leaks via engine kill. No leak.
5. New air filter.

Should I unscrew jet from bottom bowl plug and spray cleaner up? Remove air adjust screw and blow out orifice with cleaner? I’m thinking the prime tickler could not be sealing all the way up after pushed being on that right side. Does the primer flood from center of throat or from somewhere on the right side near button?

Don’t know how important or if there is a connection but before the rebuild the readings where just the opposite with lean on the right and rich on left. Then the right wrist pin cracked piston skirt and came out. This was the reason for nearly complete rebuild.
Posted By: desco Re: Different spark plug readings - 03/13/21 11:31 pm
As you only have one carb your problem is probably not carb related. Don't remember if you have points or EI. Points might cause that mixed plug condition. Or plug wires. Or valve adjustment. Is compression about the same on both sides?
Posted By: splash Re: Different spark plug readings - 03/14/21 7:23 am
No, compression is slightly higher on right side last time I checked. I have points. Maybe I should start there 🤷🏻‍♂️. Right side does miss it seems as left side is on time. After cleaning the right carbon fouled plug it still misses. I’m good on valve clearance also. That was one of the first things I checked.

Hot compression test:

60/90/120 right side under 5 kicks

60/90/110 10 kicks (Left side)
Posted By: desco Re: Different spark plug readings - 03/14/21 2:52 pm
Compression is close enough. Why, in 2021, would anyone still be running points in one of these old turds?
Posted By: splash Re: Different spark plug readings - 03/14/21 4:14 pm
Inexpensive and original 🤷🏻‍♂️

Don’t know much about electronic ignition.
Posted By: desco Re: Different spark plug readings - 03/15/21 1:44 am
I replied to your PM but I don't know if I did it right. I'm old. Let me know if you got it.
Posted By: desco Re: Different spark plug readings - 03/15/21 1:47 am
EI is easy. It either works or it doesn't.
Posted By: desco Re: Different spark plug readings - 03/15/21 1:59 am
http://www.pazon.com/
Posted By: TR7RVMan Re: Different spark plug readings - 03/15/21 2:02 am
Hi Desco, Points allow starting with dead battery, & running with low battery. You can fully loose spark on one side & keep moving under its own power.
If you ride in remote areas with no cell service that can be important. Occasionally we ride were no other vehicles pass for a week.
I don’t know what splash has done with electrical system, but prior in was a mess. All the wiring issues need proper repair. That is a foundation of good operation.

Properly serviced points work fine. EI relies on good electrical system even more than points.
Don
Posted By: desco Re: Different spark plug readings - 03/15/21 3:22 am
TR
I have ridden in parts of Nevada, Idaho and Mexico where I never saw any sign of civilization for hours on end. Once in Nevada after hours of no towns, no cars, no nothing I thought "what the hell am I doing here"? I imagined the head line in the paper," bones found bleaching in the sun next to nice old Triumph". This before cell service. Screw points.
Posted By: tiger_cub Re: Different spark plug readings - 03/15/21 5:28 am
I have been around the US extensively and I believe there hasn't been any civilisation there since about 1776


Sorry I couldn't resist it - no offence intended!! Please don't shoot me.......
Posted By: splash Re: Different spark plug readings - 03/15/21 6:30 am
I’m offended. You have not said if you were on a bike with or without points. We don’t have any kangaroos to throw boomerangs at over here in our parts of anti-people civilization. 😁 just snakes and scorpions here and there so they don’t count as civilization 😁. When did y’all start counting the kangaroos in y’all civilization? At what age can a Joey buy a beer?

All jokes aside, the whole world is still at civilization level 0.
Posted By: Allan G Re: Different spark plug readings - 03/15/21 7:43 am
Originally Posted by desco
TR
I have ridden in parts of Nevada, Idaho and Mexico where I never saw any sign of civilization for hours on end. Once in Nevada after hours of no towns, no cars, no nothing I thought "what the hell am I doing here"? I imagined the head line in the paper," bones found bleaching in the sun next to nice old Triumph". This before cell service. Screw points.

You would be able to get those points working though ok enough to get you out of that Desert, with EI youd have had no chance of fixing it.
Posted By: MarksterTT Re: Different spark plug readings - 03/15/21 3:55 pm
Originally Posted by desco
TR
I have ridden in parts of Nevada, Idaho and Mexico where I never saw any sign of civilization for hours on end. Once in Nevada after hours of no towns, no cars, no nothing I thought "what the hell am I doing here"? I imagined the head line in the paper," bones found bleaching in the sun next to nice old Triumph". This before cell service. Screw points.

You're kidding right? They'd find your bleaching bones next to a set of recent truck tire tracks and 'NO' nice old Triumph but only a small puddle of oil....
Posted By: splash Re: Different spark plug readings - 03/15/21 6:46 pm
https://hermit.cc/tmc/technote/igtiming/index.htm

I found this very informative tech help. Under the static timing I got lost at (5/G).

Under dynamic timing #4 where are the marks? I can only find one mark on the timing cam lobe.
Posted By: Wilfred Re: Different spark plug readings - 03/15/21 7:44 pm
Been using the points that were in my T100R when it was parked in the 80's and 33,000 miles later I'm still using them. They are Lucas. When I travel, I carry a spare set of Lucas original points, and a spare condenser which, of course, means I will never need them as long as they are in the bag just like the new tube and tire irons. I have experienced a bagged battery on a cold night in November 80 miles away from home with points and arrived home without a problem except that I couldn't use the heated vest if I also wanted to have lights when I came to a stop light.

Of course, I only use film to make photographs and draw pictures with pencils and pen and ink so, as I approach my 80th birthday, I guess I'm just too old to change......As an old classic bike restorer/machinist friend says " If it ain't broke, don't fix it " a lesson I have learned finally.

Cheers, Wilf
Posted By: TinkererToo Re: Different spark plug readings - 03/16/21 9:10 am
On the static timing, think about what you are trying to do. You have set the engine to the fully advanced timing positio, now you want the points to be JUST starting to open at this point. By holding the cam to full advance (clockwise) the piece of ciggy paper should be just staring to release from the points, you are rotating the points plate so that this happens at the right time. On the dynamic timing, the writer has assumed you know what you are doing! The timing marks for strobing are on the drive side, where a pointer has to align with the mark on the alternator rotor. This is pictured very clearly in the service manual.
HTH
Posted By: desco Re: Different spark plug readings - 03/16/21 2:41 pm
Come to think of it, I have not been stranded by either points or EI in almost 50 years of Triumph's. It's just the never ending messing with points I can't stand. I used to ride a lot and it was every few weeks in the garage adjusting.
Posted By: splash Re: Different spark plug readings - 03/16/21 5:59 pm
Tinkerer too, is this at TDC of the combustion stroke with the cig paper? Then says rotate 360 degrees...? Well isn’t this back where we adjusted the same points??? Should it not be 180 degrees?

I got it running with trial and error but my primary plate is way off to one side almost maxed out of travel. 🤷🏻‍♂️ I turned timing side secondary while running at idle to max RPMs and locked it down there. Drive side sounded good so I barely messed with secondary on that side while at idle.
Posted By: koan58 Re: Different spark plug readings - 03/16/21 6:37 pm
Should be at 38 deg before TDC on the compression stroke, with the breaker cam locked fully clockwise.

The breaker cam moves at half the rate of the crankshaft, so when 360 deg crank is mentioned, that means the other set of breakers at 180 deg camshaft are concerned.

If you're just guessing your timing you are taking enormous risks, and no diagnosis is possible.
Posted By: splash Re: Different spark plug readings - 03/17/21 1:44 am
Ok, at the 38 degrees mark in flywheel (first mark) this is where you line up the contact breaker arm with...? Line on cam after advancing clockwise? Or is this where you adjust the gap to where only a piece of paper can fit between points and this is on which ever piston is on the compression stroke?

Is it not preignition if it is firing 38 degrees before TDC? Something else I didn’t understand.
Posted By: Stuart Kirk Re: Different spark plug readings - 03/17/21 2:59 am
Originally Posted by desco
Compression is close enough. Why, in 2021, would anyone still be running points in one of these old turds?
All right Desco. I respect a man who speaks his mind.

But. all my "old turds" have points, partly because I am cheap but also because they can be fixed out on a desert ride if something goes wrong. Several times over the years, I have seen electronic ignitions fail out in the middle of nowhere. It's awkward. At least points give you a chance to get things going again.
And, (I probably shouldn't say this) but I have not had a terminal ignition system failure in years, using all Lucas components.

So I guess that is my reason. I'm sure others have their reasons too.
Posted By: splash Re: Different spark plug readings - 03/17/21 4:06 am
https://ibb.co/wSbhGDn

In photo, after centering the pillar bolts, I try to set the timing side secondary point plate. Flywheel is at 38 degree BTDC notch and timing side piston top of compression stroke almost at combustion stroke. I am advancing timing holding clockwise with screw driver. Notice there is nowhere the arm of the timing side points are touching the cam. I can fully deflect secondary plate on timing side in both directions and arm still does not touch rotor cam. Points stay completely closed.
Posted By: Allan G Re: Different spark plug readings - 03/17/21 7:08 am
Hi splash, set the 0.015” gap when the points are closed, if you try and set the gap when the cam is on the ramp you will never open the points.

You’ll need to strobe time each cylinder after setting the timing, there’s little chance that you’ll get it spot on by eye alone. That said a well setup set of points run sweet as a nut and are still my preferred use... the only reason I don’t use points any more is I haven’t got the time to keep on top of keeping them in time. The points on my little Honda 4 hardly ever need touching and they operate off the crank so work twice as much for the same revs as they do on my beeza, yet still the beeza needed much more attention to keep them in tune.
Posted By: Allan G Re: Different spark plug readings - 03/17/21 7:12 am
Originally Posted by splash
https://ibb.co/wSbhGDn

In photo, after centering the pillar bolts, I try to set the timing side secondary point plate. Flywheel is at 38 degree BTDC notch and timing side piston top of compression stroke almost at combustion stroke. I am advancing timing holding clockwise with screw driver. Notice there is nowhere the arm of the timing side points are touching the cam. I can fully deflect secondary plate on timing side in both directions and arm still does not touch rotor cam. Points stay completely closed.


That left hand set of points looks like it makes contact at the top but not the bottom. I’d be looking at using some 800 wet and dry folded over a few times and run them through the points, effectively sanding some
Of the contact material away and ensuring you get a good flat closure across the whole of the points.
Posted By: splash Re: Different spark plug readings - 03/17/21 7:45 am
Brand new points there Allen G. 🤷🏻‍♂️
Posted By: desco Re: Different spark plug readings - 03/17/21 12:50 pm
Brand new points but who made them? The cost of all parts for these things keeps going up while the quality keeps going down.
Posted By: Allan G Re: Different spark plug readings - 03/17/21 2:37 pm
Originally Posted by splash
Brand new points there Allen G. 🤷🏻‍♂️

As Desco said...

Originally Posted by desco
Brand new points but who made them? The cost of all parts for these things keeps going up while the quality keeps going down.

Brand new or otherwise, the points still need to have good closure on the contact faces. If you don’t create that good contact the points may spark until that contact face is eroded away enough to give a better contact, even then you’ll need to sand the surface clean to remove any pitting. The other thing is you’ll be for ever adjusting them and very frequently until this is done. I had a set of points on a D14 at one point, only part of the heel was on the cam, I was adjusting these weekly as the heel wore (with such a weedy engine you soon found when performance was falling off from timing adjusting) eventually the heel wore square, by that time I’d wore the threads out for the screw that you had to slacken for adjusting the points and had to tap the thread to a size bigger. All fun and games.

Unless your prepared to accept that “Lucas repop” points are made of pretty poor quality compared to anything else on the market for jap bikes etc and put that time in to adjust them, you’ll be better spending a few quid and getting electronic ignition, at least then you’ll enjoy riding the bike and not be getting wound up with it.
Posted By: splash Re: Different spark plug readings - 03/17/21 6:39 pm
This is a pure frustrating mess.
3 adjustments and trying to align all up is like trying to create a solar eclipses. Adjusting one forces to adjust all others then back to adjusting first one.
I follow directions and still come up with FUBAR chasing my own tail.
Posted By: desco Re: Different spark plug readings - 03/17/21 6:43 pm
Why I went to EI. Have not messed with points in 33 years.
Posted By: splash Re: Different spark plug readings - 03/17/21 6:58 pm
I’m just about f’n convinced!
Posted By: koan58 Re: Different spark plug readings - 03/17/21 9:04 pm
Hi Splash,
Points and EI both have their pros and cons.
Points assembly all in good condition and set up well will work just fine for thousands of miles between adjustment, but does require a good understanding. No-one was born with that understanding, you are learning as you go.

Just an observation from your pic, the solder blobs at the ends of the points wires appear to allow collision with the moving point when at full lift. This is not healthy, and may explain why the meeting of the points surfaces seems to be off-flat (the points arm has been distorted).
Posted By: koan58 Re: Different spark plug readings - 03/17/21 9:32 pm
Yes, if you compare the pic in
https://hermit.cc/tmc/technote/igtiming/index.htm

to your pic, you will see that the wire collars in your intallation straddle the spring, whereas they do not in Hermit’s pic. This produces the problem I pointed to in my previous post.
Posted By: desco Re: Different spark plug readings - 03/18/21 2:27 am
If you get stranded with an EI because of a low battery it's your fault not the EI. I keep my batteries on a battery tender at all times. I check the battery voltage before each ride and check it again when I get back. If it is not higher when I get back the battery or the charging system is suspect. Act accordingly.
Again, never stranded, points or EI. Time saved not screwing with points, priceless.
Posted By: splash Re: Different spark plug readings - 03/18/21 5:14 am
I am thinking the cam may be worn. The primary plate has to be set to the maximum counter clockwise position for line to match up near pointer when strobing. I don’t know what else can cause for max tolerance fully deflected all the way like this. Maybe the auto advance?
Posted By: TR7RVMan Re: Different spark plug readings - 03/18/21 8:15 am
Hi splash, It is very common to have back plate at or near limit of travel. It doesn't matter. Getting the timing correct is what matters. You can/will compensate with the sub plates.

Trust me a worn cam will not cause this.

You need a cam advance holding tool. Take a piece of bailing wire. Bend into washer shape that will fit over end of points cam, yet clear center shaft.
Remove AAU bolt. Place your bailing wire over end of AAU. Place larger flat washer over wire. {ut bolt back in finger tight. Hold cam clockwise to stop. Snug bolt & cam will stay at advance.

Don't use thin paper or cellophane. Get an ohm meter. You can use test light if you don't have ohm meter.

Remember you want points opening. Opening is what triggers spark.

Rotate motor until 38b mark lines up on rotor. Note, there are 2 marks on rotor. Only one is for you motor. If you have TDC tool use it to find 38b. Look in spark plug hole. If tool goes in & piston is at top that's TDC back up motor a little. In any case the TDC tool will go into slot at one of the marks. Put X through unused mark on rotor so you know that's wrong mark. The TDC holes in crank are actually slots. You can see them with flash light & mirror & feel them with screw driver. Just so you'll know.

I always start with front points (L cyl). Doesn't matter, but I like to. Turn motor until it looks like front points are ready to open. Hook up ohm meter with alligator clip to the curved points spring. Other lead to head fin. Now, this is important. Read meter with points closed. Record reading. Now turn motor until you see points open. Record reading. Notice you'll see about 3ohm & 70 ohms give or take a lot... the point is you want to see the change when points open. So memorize what meter does when points open. That's what you want to recognize, the moment points open.

Now back up motor & come forward rotation. Turning rear wheel on center stand is easy way. Spark plugs out. You always want to measure with motor rotating forwards, never backwards. If you pass the opening too fast. Back up motor a lot, then come at it again. This compensates for backlash in timing gears.

So AAU locked in advance. Ohm meter hooked up. Rotate motor forwards until meter shows points just opened. Go easy it happens quickly when you're at the sweet spot.

Look at line on rotor. Remember your sub plates & slot are centered. Your gap .015". Now move back plate until you are on time or close as you can get.

It can take several trial & error adjustments at first. If you run out of slot, then move sub plates. However double check point gap first as it can change moving primary plate. It just does...

Now go back & turn motor until points open again per meter. Move sub plate to trim the timing until you see meter read points open at same time line is on pointer.

Now move to rear points. Again verify gap. Now, trim timing on rear points my moving sub plate.


Expect to take a few hours until you get the hang of it. Probably all day Saturday actually. Takes time & practice. I can do all this in about 10-15 min. Like riding a bike or surfing. Looks easy & it is once you get the hang of it.

After all this cut some strips of copy paper. Dip in gas or carb spray. Place between point faces & clean off any oil or grease residue. Dry with dry strips of paper. Put a dab of point cam lube on the rubbing block. Lubricam SL-2. Ebay if local parts store doesn't sell it. This is very important. Or rubbing block will get hot, melt/wear quickly & gap will change. Properly serviced the points will last many thousands of miles & should cover 3k miles between servicing without problems. I do it all the time. Have for years.
Don
Posted By: splash Re: Different spark plug readings - 03/21/21 6:53 am
So I finally figured out the points with timing light. Fires right up on first kick. Still have low idle issue when from high RPMs then to pulling clutch in to coast or put in neutral to coast to a stop. Usually by bumping the throttle it will settle at idle OR if I leave it in gear to slowly whin down the RPMs. Is this common?
Posted By: Allan G Re: Different spark plug readings - 03/21/21 7:41 am
Sounds like your running concentrics with screw in pilot jets for that last one splash.
Posted By: splash Re: Different spark plug readings - 03/21/21 9:24 am
Tell me more. Is there a page in the repair manual? What does running concentric mean?
Posted By: gavin eisler Re: Different spark plug readings - 03/21/21 10:56 am
Your carb is an Amal Concentric ( model name), early concs had a pilot jet screwed into the roof of the float bowl, this gives poor idle. later concs have a fixed bush jet which lives directly behind the pilot air adjusting screw. Either way the idle jet is tiny ( 0.016") and is the first to block. Clean with a #78 drill.

i am struggling to understand Allans advice to set the points gap when they are closed, how does that work?
Posted By: triton thrasher Re: Different spark plug readings - 03/21/21 11:44 am
Originally Posted by splash
So I finally figured out the points with timing light. Fires right up on first kick. Still have low idle issue when from high RPMs then to pulling clutch in to coast or put in neutral to coast to a stop. Usually by bumping the throttle it will settle at idle OR if I leave it in gear to slowly whin down the RPMs. Is this common?

If we can assume that the points gaps and timing are now correct and equal on both cylinders (I’m dubious of that, after reading your previous posts) and the engine has warmed up, then an engine that slows down too much when you shut the throttle, then picks up slightly, can be a sign of a rich pilot mixture.
Posted By: splash Re: Different spark plug readings - 03/21/21 10:39 pm
Triton with the forever inviting posts once again. Thanks for your help. I’m running short straight pipes where it needs to be somewhat rich.
Posted By: Allan G Re: Different spark plug readings - 03/22/21 3:49 pm
Originally Posted by gavin eisler
Your carb is an Amal Concentric ( model name), early concs had a pilot jet screwed into the roof of the float bowl, this gives poor idle. later concs have a fixed bush jet which lives directly behind the pilot air adjusting screw. Either way the idle jet is tiny ( 0.016") and is the first to block. Clean with a #78 drill.


Those screw in pilot jets are troublesome when shutting off throttle and coming to a stop, there just isn't enough fuel at the right point when you need it most. by having the pressed in bush (or a premier carb with a screw in jet directly opposite the pilot air screw) there is, and you don't get the suddern engine dying.

Just adding on from Tritons comment, the same instance wouldn't happen above if you were stationary and revved the engine up and let it fall to idle as the fuel isn't being moved back and forth in the bowl. If it does it here then the idle mixture most likely isn't set correctly and the slide probably is too lean also.

Originally Posted by gavin eisler
i am struggling to understand Allans advice to set the points gap when they are closed, how does that work?

Ha! you got me, Id like to say i was testing folk to see who was reading what I wrote, but no I was just having a dopey moment.

Yes, set the marker on the points cam to the heel of the points and set the gap there. Its advisable to remove the screw and using a soft punch, give a few light taps to ensure the AAU has seated square and isn't running off centre.
Posted By: TR7RVMan Re: Different spark plug readings - 03/22/21 5:54 pm
Hi Splash, A ‘70 Tiger would have come with Amal MKI. A round float bowl, with pressed in .017 pilot (idle) jet, behind mixture screw.

If you remove mixture screw, look in hole with flashlight you’ll see tiny brass bushing with .017 hole in it. Strip back some 18g stranded wire a few inches. Stick 1 strand into hole. You have to be steady as hole is tiny. This will push dirt into passageway. Shoot carb cleaner into hole & it usually will blow dirt back into float bowl. Remove drain from bowl first. Open fuel tap & let some fuel flush bowl.

A newer premier version concentric will have a cross head brass plug on opposite side of mixture screw. This brass is head of removable pilot jet. The very first version had removable pilot jet inside above float bowl. Highly unlikely you have earliest carb.

There is also new non premier concentric with silver cross head screw. It has pressed in jet. The silver cross head can be removed to make jet cleaning easier.

Lots of changes & carbs shaped the same.

MKII concentric has square bowl & looks Japanese like Honda carb. No tickler.

To check for worn out carb/slide bore, heat soak motor. Pull over & let motor idle 5-10 seconds. Open throttle slowly as possible. No matter how slow you open throttle motor should not falter or die. Some wear will falter, bad wear will die. This is tiny opening only .005” or so. You can pass the bad spot by opening more quickly, then motor will rev as expected. Don’t jump to conclusions. Do this test several times over a few rides. Cheating mixture about 1/4 lean (out with screw) will make idle feel worse, but improve dying somewhat. New carb is best cure. New slide may help temporarily.

Make sure idle is not too low in every case.

Street bikes tend to not like straight pipes. Not to mention peace of the island. Emgo repro original mufflers work well & not too costly. The motor is sensitive to air filter changes also. Paper elements can make make mixture do odd things.

Factory settings only work for factory stock bike & ‘70s fuel.

You have much going on at the same time. Will take some sorting to work this out.

Remember the basics start with good reliable power to both coils, good points & point wires to coils. Good condensers, good plug wires & good coils. Good advance unit & timing.

On paper it’s easy. Real life is lots of hard work, often frustrating if you don’t have experience.
Don
Posted By: koan58 Re: Different spark plug readings - 03/22/21 11:34 pm
Hi Splash,

You said “I’m running short straight pipes where it needs to be somewhat rich.”

This is not quite right.

A free-er flowing exhaust system (and/or a free-er flowing inlet system) will allow more air through the engine.
That will often require larger main jets and possibly adjustments to the needle position, needle jet itself (uncommon), throttle valve cutaway (uncommon).

These adjustments (correctly done to compensate for the increased air flow) will result in a correct mixture, NOT a richer mixture. On a single carb engine like yours, this will be correct for both sides.

If you are still seeing big differences between the 2 cylinders in sooting of plugs, and you are sure that the mechanicals (compression, valve condition/clearances, rings) are good, then all that is left is ignition timing.
A spark firing at the wrong time on one cylinder could produce sooting on that cylinder.
If you have strobed one cylinder to be correct, now try the other cylinder (the other plug lead).

It takes 2 cylinders to tango!
Posted By: chaterlea25 Re: Different spark plug readings - 03/23/21 12:18 am
Hi Splash,
If you remove the centre bolt of the AU unit a larger washer can be temporarily fitted, this can be used to wedge the cam in the fully advanced position which will free up one hand and make it easier to set the points opening at 38degrees BTDC.
This is the full advance position, the AU retards the timing for starting and low revs timing
(Don't forget to remove the washer when finished setting the timing)
The mark on the cam looks like the max opening, lined up the the rubbing heel of the points is where you set the points gap

John
Posted By: splash Re: Different spark plug readings - 03/23/21 12:46 am
Plugs now look the same after running for a few days after setting timing. Electrode is burnt toast color but arm and circumference where threads begin is black carbon.

Will try cleaning out behind mixture screw as Don explains above.
Posted By: desco Re: Different spark plug readings - 03/23/21 1:28 am
Arguing about points vs EI is about as senseless as arguing about religion or politics. You believe what you want.. No one is going to change your mind.
Posted By: koan58 Re: Different spark plug readings - 03/23/21 2:26 am
Plugs now look the same after running for a few days after setting timing. Electrode is burnt toast color but arm and circumference where threads begin is black carbon.

That sounds good enough Splash, no need to mess with it further. Ride it and enjoy!
Posted By: splash Re: Different spark plug readings - 03/23/21 6:28 am
It’s just another option that’s all, Desco. I can go EI one day soon or later 🤷🏻‍♂️. Just a different way to skin the cat. After a fresh rebuild I gotta go the inexpensive route for now and learn.
Posted By: Allan G Re: Different spark plug readings - 03/23/21 5:02 pm
Originally Posted by splash
Plugs now look the same after running for a few days after setting timing. Electrode is burnt toast color but arm and circumference where threads begin is black carbon.

Will try cleaning out behind mixture screw as Don explains above.


The electrode colour is good, what grade plug are you using? N3 N4 etc...

With the correct plug you want to see the first 3 threads up the plug showing a discolouration to the metal,
Posted By: dave jones Re: Different spark plug readings - 03/24/21 4:31 pm
I'm glad that Splash has got this problem sorted.

I am going to hijack this thread and say that I tried to get my plugs the same colour as each other but without success. I had my own thread on this once.

Single carb 650 TR6R 1967. I tried doing everything to the points (strobed to perfection). One plug is too light and the other too dark. The dark cylinder does have a bit of oil in it but the plug is dry dark but not fully black or wet looking. I haven't tried a new condenser on the darker side or maybe it is a worn inlet guide on light side? Can this do it? How about a leaking head gasket?

Dave
Posted By: Allan G Re: Different spark plug readings - 03/24/21 9:50 pm
It can be a lot of things.

Two good diagnostic tools are a compression tester which are best done on a warm engine and with the throttle fully open.

The other is a gunson colour tune. This is not only good for setting idle
Mixture but also for diagnosis of oil or over rich contamination.


If you are getting puffs of smoke on over run it’s valve guides. If your getting smoke on acceleration then your possibly looking at rings/cylinders.

If one plug is excessively pale on standard jetting, possibly even that side exhaust pipe looking a bit blue then you could have an air leak where the 1-2 manifold mounts against the head.

If your only using a bit of oil or slightly too rich of mixture then it won’t always be visible in the exhaust smoke but it will show on your plugs. Hence why you should try the colour tune and compression tester.
Posted By: dave jones Re: Different spark plug readings - 03/25/21 8:36 am
Thanks, Allan. Had not seen any smoke. The pipe on the light side is blue but the other side is catching up and looking a bit blue, too. Is an air leak most likely at manifold? The joints look solid. Can air actually pass down the inlet guides?

Dave
Posted By: Allan G Re: Different spark plug readings - 03/25/21 1:31 pm
Hi Dave,

An air leak can occur anywhere, but with it being a single carb machine and with your plug diagnosis it limits its possibilities, or at least i think so....

In my opinion, if you have the leak at the carb mount then you would be more likely to see the plugs ceramic white on both pots, you could have a leak at the exhaust, which would draw in air, youd find some back fire and most likely an increase in blue in the pipe. Points ignition can have an effect also as cylinders will be timed differently, if one side is more retarded then the other then it will run hotter...

so a leak at the point i mentioned is the only thing I can think of, unless as I say your using points ignition and there was some failing in that. Electronic would fire both sides at the same time and at 360 crank degrees apart respectively so that wouldn't throw it out. If the condensers or the coils were crapping out, even just one of them, you'd know by how it rides, it would pull fine until you placed a higher demand on the engine (so more speed or climbing a hill) then it would pop and fart and youd have little power at all.

You could compare the primary and secondary resistance across the two coils and check they are somewhat the same. primary resistance should be 4 ohms, I cannot remember what secondary should be.

I doubt youd get any air pulling down the guides, youd get the oil symptoms firstly as previously described.
Posted By: dave jones Re: Different spark plug readings - 03/25/21 3:12 pm
Thanks again, Allan.

The bike has always run surprisingly well considering it is not tip top, wear wise. Starts first kick even after a long lay off. Does require choke to start and for a short distance on the road. I thought maybe it was too weak but tried using the choke when fully warmed up on the road but this didn't improve running.

As I said i have noticed more blueing on both sides recently and looking back this may have started when I changed the timing from 36 to 38 before tdc. This seemed to make it more powerful (might be my imagination) but could well be making it run hotter. I retarded the timing because I thought it would be better with modern petrol but I only have low comp pistons.

Could just be running hotter both sides but burning a bit of oil on left but not enough to cause a wet plug. I had the carb bored and the slide sleeved so can't try a different slide (no 4). Could file a bit off but then I would be stuck.

The carb sleeving didn't make any difference to road running but made it so that it idles properly. Previously you had to set it for one or the other. If set for a regular idle it would eight stroke around town. When it was set for the road it would idle but would gradually peter out. I don't understand this. You would think it would idle or not idle! Now you can set it for a regular idle and it still runs smoothly around town.

Did get some help on needle positions from Nick Smith. I thought mine was on 1 he said it should be 2 and turned out that it actually is on 2!

Dave
Posted By: John Healy Re: Different spark plug readings - 03/25/21 3:24 pm
This is absolutely normal. Not having to use the choke is what is abnormal.

Quote
Now you can set it for a regular idle and it still runs smoothly around town.

What are you setting: Pilot air screw or idle screw?
Posted By: Allan G Re: Different spark plug readings - 03/25/21 7:18 pm
If it’s 8 stroking around town then your slide is probably too rich. You also need a certain amount of clearance around the slide, too much abs you loose the vacuum applied against the jet and pull less fuel through and too tight and you pull more fuel through. As long as it works smoothly and freely then jet the bike from there.

You spend a surprisingly large amount of time riding on the slide setting. But the other thing to note is the needle jet and needle wear. I like to replace these as a set. As these wear your making the flow past the needle jet greater, this will cause your 8-stroking. Change these and go for your run, try some rural routes where you can get your speed up but also be slowing down for bends etc, this will give you a good idea of if you need to go leaner or richer. At this you won’t spend much time on slide position. Mark the throttle at closed, fully open, half way then 1/4 and 3/4 positions and then mark the body so you know which throttle position your riding at (I tend to use some Insulating tape)

Once your happy with your needle position and the bike is pulling cleanly as you decelerate and accelerate through bends and adjusted to suit.

Top slot on the needle is pos 1, bottom is pos 3, pos 1 is a leaner setting.

Now, with the engine nice and hot, put it on its stand and adjust the idle
mixture, screw the horizontal screw out as far as you can before the revs start to drop, then steadily screw it back in, the revs will rise then start to drop again. Find the sweet spot here and leave it. It could be revving at 2000, don’t worry at this point. Adjust the idle speed by screwing out the diagonal screw until your at about 1000 rpm. Now check the horizontal screw again, and again find that sweet spot. Depending on how far out the throttle slide was, depends on how far out if any the mixture (horizontal) screw is)

Then go on a town run, where your stop-go through traffic. You’ll find out soon enough if your running rich or lean. 1 slide too lean is usually the slide where the engine wants to hesitate or stall when pulling away. If you have to feather the throttle, go one slide richer.
If the bike pulls but it’s a bit sluggish, go one slide leaner.

The lower the slide number the richer it is, the higher the number the leaner it is. With a standard exhaust your usually somewhere between a 3 and a 3.5 slide. But how the bike responds best is the right setting.

Also going to a bigger number 38 degrees from 36 is advancing the ignition This will give you a steadier tick over and better acceleration. You might find a slight drop in power at top speed however. But this is compared against the optimum setting.... this you need to find out yourself.
Posted By: TR7RVMan Re: Different spark plug readings - 03/26/21 7:25 am
1/8sHi splash, Mark grip with masking tape in 1/8s. Take cable slack up for zero. Be accurate. Mark zero & full. Then divide by halves until you have 1/8s.

Print this tuning guide & take in pocket on road tests.

https://static1.squarespace.com/sta...2/1481956877861/Amal+MK2+Carb+Manual.pdf

Make sure you have stay up float & aluminum tip viton needle. Set float level.

Make sure you have PERFECT needle jet & needle. Any wear will skew results & you'll never get carb to work. If in doubt get both new. Get only genuine Amal parts.

'70 Tiger is one of the best bikes Triumph ever made. They can be made run perfectly. One of the best running of all. If not, it's not right.

It takes time & practice to tune carbs. Several road tests & comparing tuning guide. Always keep throttle opening in mind. This tells you what part of carb is controlling mixture. The tuning guide will show you what to do to change mixture.

Want to mess yourself up? Don't mark grip, don't set float level, don't get perfect needle jet & needle. Don't print, study & take tuning guide on road test.

Tip, main jet can be hard. Find a moderate up hill. 65 mph or so full throttle. Go larger main jet until 8 stroking. Misfire that goes ah ah ah ah, back off throttle it stops instantly. Wide open, comes right back. Go one main jet size smaller at a time until 8 stroking stops at full throttle. Find a road test route that works for you. Keep same route so you can get repeatable results & feel what changes does what. I like to start with main jet if bike runs good enough to allow it to run 65 mph.

So what does the snap throttle do? That is very strong indication of cutaway.

With motor heat soaked pull over & let idle. Turn throttle slow as possible. If motor dies or wants to die just off idle, it usually indicates carb is worn out. I fyou cheat mixture lean 1/4-1/2 turn out from best idle with mixture screw, the slow throttle is better, that confirms wear slide/bore. Don't jump to conclusions. Get repeatable results over several road tests.
Don
Posted By: Allan G Re: Different spark plug readings - 03/26/21 8:10 am
And what do you gain by marking 1/8ths? Or 16ths for that matter? If you mark in 1/4 you have 5 marks which hit the same 5 points as indicated by the tuning guide which you kindly linked to.
Posted By: dave jones Re: Different spark plug readings - 03/26/21 9:00 am
Thanks Allan and Don.

Don is mixing me up with Splash. I shouldn't have hijacked this thread.

John Healy. With the sleeved carb the idle is set a bit richer than 1 1/2 turns for good running.

The point I was making was that even though the bike is a smooth runner through the range it still has plugs of different colours.

I had better leave this thread now


Dave
Posted By: John Healy Re: Different spark plug readings - 03/26/21 1:04 pm
Quote
I fyou cheat mixture lean 1/4-1/2 turn out from best idle with mixture screw, the slow throttle is better, that confirms wear slide/bore.

If you have a "worn out" carburetor it usually refers to the slide bore is worn oversize. Most the wear typically appears at the bottom edge of the slide and adjacent area in the body. This lets more air enter the intake manifold reducing the vacuum signal on the fuel metering systems. The most affected period is at very low throttle openings.

Turning the air mixture screw out 1/4 to 1/2 turn further reduces the vacuum. It is as if the body was worn more. Turning the air mixture screw in a 1/4 to 1/2 turn increases the vacuum signal. This compensates for the lack of the vacuum lost by the worn slide/body.

Years ago Amal increased the clearance on the slide for safety reasons. It help prevent the slide from sticking when the mounting hardware is over tightened. To do this they had to make changes to compensate for the loss in the vacuum signal. They did this by making changes to the body and the related bits.

If this clearance isn't maintained when sleeving the carb it throws all of the low throttle opening jetting askew. To get the low speed jetting to work as designed you are looking for around .0035" clearance. If less, corrections have to be made and you have to be very careful when tightening the mounting hardware.

For design/engineering reasons, if you choose to use a Stay-up float, you should always use it with an aluminum needle. Otherwise the old white float and brass needle still work as designed.
Posted By: John Healy Re: Different spark plug readings - 03/26/21 2:23 pm
To the point of different spark plug readings: The differences can be down to the difference in air flow (velocity) from the draw of air created by each cylinder. The air velocity is dependent upon a handfull of conditions that are independant of the carburetor. You must consider the condition of the pistons rings, valve seating, cam overlap, ignition and a handfull of other factors.

If the vacuum signal of each cylinder provided by the downward movement of the piston, is not the same, neither will the amount of fuel delivered be the same.

While the effect will be slightly different for a TR6, with its single carburetor, as it is for a T120 you can see differnce. A good place to start looking into this, as a factor, is a compresion test. Without a large air plenum to balance off the vacuum among cylinders, if the air velocity from one cylinder is less than an other, the amount of fuel delivered to each cylinder can vary. It isn't always the carburetor.
Posted By: Tridentman Re: Different spark plug readings - 03/26/21 6:07 pm
Some individual models of the BSA pre unit twins exhibited what is known as "induction bias".
For reasons related to what John H has has described together with tolerances etc with a single carb each cylinder did not get the same as the other in terms of cylinder filling etc.
It was so much of a problem that BSA made available a tapered gasket to go between the head and the carb to direct the incoming charge towards the weak side.
Might be worth trying it on your TR6.
HTH
Posted By: triton thrasher Re: Different spark plug readings - 03/26/21 6:38 pm
I can tell you for sure that mixture bias happens on single carb Triumph twins too.

I don’t know if slanted spacers fix it, but I know that twin carburettors can fix it.
Posted By: koan58 Re: Different spark plug readings - 03/26/21 7:28 pm
TM and TT, any thoughts as to the cause?
Is it always to the same side, or does it vary? That would be an important clue.
Posted By: triton thrasher Re: Different spark plug readings - 03/26/21 7:56 pm
Originally Posted by koan58
TM and TT, any thoughts as to the cause?
Is it always to the same side, or does it vary? That would be an important clue.

Fluid dynamics ain’t so simple as putting a Y-piece in front of a carb and assuming everything will be fine.

The left one was weak on my bike.
Posted By: koan58 Re: Different spark plug readings - 03/26/21 8:13 pm
"Fluid dynamics ain’t so simple as putting a Y-piece in front of a carb and assuming everything will be fine."

Why isn't it? Fluid dynamics has no left/right preference.

If the only example you've experienced is your own bike, I'd be tempted to explore the other factors JohnH mentioned in his second post.
Or even the precise profile/position of the "parting of the ways" inside the manifold.

I'll be waiting for someone to bring Coriolis into it!
Posted By: Tridentman Re: Different spark plug readings - 03/26/21 9:27 pm
Koan-- IMHO the important factors are wear and tolerances.
JH has IMHO correctly pointed out how wear--differential between cylinders can affect how one cylinder performs compared with its supposed twin.
Tolerancing on the Y manifold, how the Y manifold sits on the head studs, the position of the head studs---just to give some examples---can affect one cylinder relative to the other.
In the case of the BSA pre unit twins I believe that induction bias was found more on the 500cc A7 than on the 650cc A10---but don't ask me why!
The concept of the tapered gasket is to "direct" the gas/air mixture from the carb towards the cylinder running the weaker.
Note that I am not suggesting that induction bias IS the cause of Dave's problem--it is just one of the various possibilities.
Posted By: John Healy Re: Different spark plug readings - 03/26/21 9:42 pm
Dave You see, it is Rocket Science beerchug

It also could be what you are seeing is the difference in how well the rings are at oil control. It goes on and on. Where is Dr. Rob Tuluie when you need him.

Unless the problem is keeping you from riding I would go riding.

Coriolis: I thought that they were a Mafia family.
Posted By: koan58 Re: Different spark plug readings - 03/26/21 11:09 pm
“Dave You see, it is Rocket Science”

John, it isn’t obvious which Dave you were talking too, but as at the end you mentioned “Coriolis” I guess it was myself.
BTW I only mentioned that word jestingly, it is the phenomenon that is supposed to determine whether bathwater spirals down the plug-hole clock or anti-clockwise, depending on whether the bath is in the north or south hemisphere.
In truth, what happens at the plug-hole is determined by local differences such as waste pipe verticality, exact shape and lateral levelling of the bath blah. Which is what I suspect this “intake bias” amounts to.

I appreciated your “Rocket Science” until TM took the wind out of it by saying it was the BSA 500’s(A7) not the spaceage 650’s.

Some things mentioned by TM seem quite possible, in particular the fit (with possible steps) between manifold and head. Also excess gasket could be an issue here too.

It seems that Splash is happy with his plug readings having now got his ignition timing correct, and we are subsequently discussing dave jones plug readings (which are different between shades of tan but the bike works fine).
I think that is the realistic objective, not to aim for identical depths of colour, but beware of white insulator and top arm burnt white for much of its length. Carbon on the end of the threaded end doesn’t concern me at all.

Only my thoughts, Corleone may have had a different view, but perhaps on vespas rather than britbikes!
Posted By: Hillbilly bike Re: Different spark plug readings - 03/27/21 1:46 am
These plugs are from my T140 after a 12 mile run in high gear between 55-75 mph on a backroad in a a sporty manner but not wide open throttle. The plug shows slightly rich combustion and a slight difference in color. Fuel is 90 octane non ethanol..

Attached picture 5jEkJaX.jpg
Posted By: koan58 Re: Different spark plug readings - 03/27/21 2:08 am
A pic can be misleading, but they look white and hot to me, especially the left one.
Posted By: desco Re: Different spark plug readings - 03/27/21 2:35 am
I was thinking the same thing. But who knows what is right for a certain bike? The plugs and valves on my 56 T110 were snow white and it was a rocket. But that was (oh my God) 58 years ago.
Posted By: Hillbilly bike Re: Different spark plug readings - 03/27/21 3:03 am
How about this one, same bike but a harder run and cleaner shut off than above....Surprized you missed the clipped electrode NGK Competition plugs...The engine has Mikuni flatslides.

Attached picture 76vqPIH.jpg
Posted By: desco Re: Different spark plug readings - 03/27/21 3:19 am
I saw that detail on the plugs. What's the advantage? I have found that Denso plugs cured a misfire at one point in a long ride, on one bike, and have been using them ever since.
Posted By: koan58 Re: Different spark plug readings - 03/27/21 3:23 am
"How about this one, same bike but a harder run and cleaner shut off than above....Surprized you missed the clipped electrode NGK Competition plugs...The engine has Mikuni flatslides."

So what difference does it make? Doesn't heat affect it just the same?
Posted By: TR7RVMan Re: Different spark plug readings - 03/27/21 4:14 am
Hi Allan, I like to mark in 1/8ths as there is a fair amount of overlap in my way of feeling carb. Main jet is simple. Needle clip, cutaway overlap. I try to gauge which way I want to go with this. Snap throttle is basic test for cutaway, but I find it overlaps into running on beginning of needle taper.

I find it gives me a better gauge of were slide is that 1/4s. Just a matter of personal preference I guess.

Mark it anyway you choose. However, you must know where slide is.
Don
Posted By: TR7RVMan Re: Different spark plug readings - 03/27/21 4:23 am
Hi John, I did not misspeak on turning mixture screw out.

I cannot explain this. Why that helps. I've observed this on worn carbs several times now. Something odd happens making motor die at like .005" lift, maybe even less. The motor will flat die. Even riding rolling on throttle very slowly motor will die, but... momentum keeps it spinning & it restarts.

I've always thought it was lean, but mixture screw in makes it worse. Out makes it better. I don't get why. Should you get worn carb job through shop, heat soak it & see if you experience similar.

Does 91 E10 California fuel effect this? 100% of time so far. new carb(s) cured this 100%. No matter how slow you work throttle with new carb you can't make it die or even hesitate, it just keeps running smoothly & rpm increases ever so slowly.
Don
Posted By: dave jones Re: Different spark plug readings - 03/27/21 8:40 am
I didn't manage to leave the thread! My light plug is like Hillbilly's light one but the other is a fair bit darker. As John and others said said I think it must be wear on one side more than the other in my case.

Looking in the Triumph workshop manual I saw that it does mention the bias between cylinders and says to tune the bike to get the left one correct. I think that if I did that the other would be v. hot as my dark one is the left..

John- when you mentioned valve seats did you mean leaking, sunken or both?

Dave
Posted By: Hillbilly bike Re: Different spark plug readings - 03/27/21 9:11 am
Originally Posted by koan58
"How about this one, same bike but a harder run and cleaner shut off than above....Surprized you missed the clipped electrode NGK Competition plugs...The engine has Mikuni flatslides."

So what difference does it make? Doesn't heat affect it just the same?
The plug in the photo is not too hot,it might be the photo or you like many others accept rich mixtures as normal. Refer to what JH says about chokes on cold engines,...Most don’t need them because of over rich mixtures....the Amal Concentrics in good shape work as intended on a stock engine. But the on size fits all pilot jet can be a hinderance when tuning for different situations. And In 2021 I feel no need to piss fuel when using ticklers on carburetors costing near $200 each new...
The results always talk the truth,.the leaner mixtures carefully tuned for the way the bike is ridden give sharpest throttle response and more power. There’s no detonation, no holes in the pistons, no overheating....It works for me and I’m far from the smartest guy here, but not afraid to try different stuff...
Posted By: dave jones Re: Different spark plug readings - 03/27/21 1:46 pm
You know your stuff, Hillbilly.

I read somewhere else as well that a white insulator but with a ring of grey at the base means maximum power. Also I read that setting the idle as weak as possible without spitting back saves a lot of fuel around town.

My bike is in that state where generally I use the "If it ain't broke don't fix it" although things aren't tip top. I like to discuss things on here just in case.

Dave
Posted By: John Healy Re: Different spark plug readings - 03/27/21 3:18 pm
leaking
Posted By: Hillbilly bike Re: Different spark plug readings - 03/27/21 5:04 pm
Originally Posted by dave jones
You know your stuff, Hillbilly.

I read somewhere else as well that a white insulator but with a ring of grey at the base means maximum power. Also I read that setting the idle as weak as possible without spitting back saves a lot of fuel around town.

My bike is in that state where generally I use the "If it ain't broke don't fix it" although things aren't tip top. I like to discuss things on here just in case.

Dave
I know a few things but actually I dislike engine work and tend to use proven shortcuts...hillbilly engineering....
I do listen to John Healy because he says what not to do based on experience...
my T140 with flatslides is jetted lean for low speeds. It needs the enricheners left on for a few moments even in warm weather....once warmed up it runs flawlessly with none of that cammy sounds so many Triumphs have when trolling along in second gear in town...
To run lean jetting you need to be in touch with the engine’s needs. None of that snapping the throttle open like a kid on a 2 stroke 125....Learn to roll it open with respect , the bike doesn’t accelerate any faster with wacking the twist open......
Posted By: John Healy Re: Different spark plug readings - 03/27/21 5:26 pm
Quote
Something odd happens making motor die at like .005" lift, maybe even less. The motor will flat die.
This is the point where the idle carburetor is switching to the main carburetor. It is the point where the secondary transfer orifice changes from delivering air to the idle circuit to delivering fuel to the main carburetor. There are many things that can upset this sensitive transition. The secondary transfer port is the larger of the two, and under the slide, of the two holes either side of the back edge of the slide. For this to work it must be clean and the orifice sized. Also the pilot jet must be clean and the orifice sized.

Flat dying is a classic sign of a lean condition. I would start by making sure the secondary transfer port is clean and sized (.040"). To trick it place the tip of a finger in front of the slides cutaway; then place the tip of your finger on the slide and lightly push it back and see what happens. This could give you some clues

In most carburetors a mechanical operated pump (often called an accelerator pump) connected to the throtlle mechanism does the job of the secondary transfer port.
Posted By: TR7RVMan Re: Different spark plug readings - 03/28/21 8:24 pm
Hi John, I can assure you in every last case the worn carb was very carefully cleaned & full flow through both drillings as well as idle passages was verified 3 times. I will not spend $200 on carb due to clogged/dirty/partially blocked passage. Tune of carb was carefully road tested & set. Tune of bike, grounds, electrics, spark, air leaks, was verified perfect in every case over a period of road tests.

I agree 100% lean will cause dying. The leaning of mixture screw helps to a degree. Of course motor is not best idle mixture. This has puzzled me for some years now.

So if there is not a odd super rich (you see not puff of black smoke), then the additional air flowing through idle passage somehow effects the transfer such it helps to reduce they dying. Once carb is really worn bad, even that doesn't help. I find it most interesting why the air screw out farther helps.
.
Raising idle helps as expected, but to really help you have to get to 1150-1200+ even 1800 I've seen many do that. I don't know how they can ride like that as it's very inconvenient but they do.

I'm currently overhauling my motor & inspected slide/bore wear of my premier. I've observed almost zero wear in bore or slide after 10k miles. Original air filters from new with covers perfectly sealed to alloy boxes. Original wire/gauze elements.

The reason I like to whip dead horses is they can't run away. I'm too slow to chase the live ones!
Don
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