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Hard Starting Triumph 650 #781060 08/10/19 12:55 am
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tiger_cub Offline OP
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My 66 Triumph with 70 motor is really hard to start. Its a 650 single carb fitted with a Morgo 750 kit and Boyer ignition. I have great spark so I suspect fuel flow. 930 Carb looks OK, it has a 3 slide, needle in middle position and I have fitted a choke although that doesn't seem to have made any difference. Once warm it goes great but it is a real pig to start and takes a good while before it will run properly. I can detect a possible kick back trying to start it and I cant retard the Boyer any more as it is up against the extreme of the slots. Initially it starts then cuts out, have to be really steady with throttle. I am going to try new fuel ines as they have aftermarket filters in them and make sure the bowl filter is OK. Any thoughts appreciated.


1966 Triumph Thunderville
1968 BSA B40M Roughrider
1970 TR6C
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Re: Hard Starting Triumph 650 [Re: tiger_cub] #781065 08/10/19 1:25 am
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I've found that hard starting bikes are either a problem with technique, or carbs.
Let's assume that you've been riding a while, so I would check the carb settings. Have a look at how far the slide is adjusted from closed.The closer it is to closed, the more speed of the air across the jet and the more likely that fuel is getting sucked into the combustion chamber. The common technique used for tuning low speed is to adjust the air bleed screw for the highest idle speed, then lower the slide adjustment screw.
The best idle and consequently the best starting is had when you follow this method and end up with a slide that is nearly closed at idle. You sometimes find bikes so badly out of adjustment that the bike is idling on the main jet circuit instead of the idle jet circuit. They'll run, but not good and they'll really be an SOB to start. In those cases, you'll like find at least a partially blocked idle jet.
Cheers,
Bill


Bikes
1974 Commando
1985 Honda Nighthawk 650
1957 Thunderbird/T110 "Black Tiger"
Antique Fans: Loads of Emersons (Two six wingers) plus gyros and orbiters.
Re: Hard Starting Triumph 650 [Re: tiger_cub] #781075 08/10/19 5:17 am
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Something that can make them really hard to start is when there is rubbish in the pilot jet port. This can be from fuel evaporation. The plug can be mobile so it isn't always blocking the jet. Though you can "drill" out the deposit if you can trap it, the best way is modify the carb by drilling out the hztl blanking plug then tapping it to take a shortened idle jet screw. That way both sides of the gallery are open and can be blown through. Later carbs have this mod done by the factory.


68TR6P rebuilt as a C
70 TR6R
Re: Hard Starting Triumph 650 [Re: tiger_cub] #781079 08/10/19 6:45 am
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You might be battling with multiple problems. Has it ever run 100% properly in your ownership?

A few things I'd consider doing..

Size the pilot jet as discussed numerous times on this forum.

Renew the .106 needle jet if it hasn't been done in recent memory.

Thoroughly check/verify timing with a strobe light. It should idle at about 7° -8° and advance with revs to 37° - 38°. Take no chances with timing.

Check carb has insulator to stop heat migrating to carb. (helps hot restarts)

Check and verify battery condition is in good health.

Do a proper voltage drop test to the Boyer under load.

Set idle mixture with motor thoroughly warmed up.

Re: Hard Starting Triumph 650 [Re: tiger_cub] #781082 08/10/19 7:55 am
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Hi tiger_cub, That is often the sign of a clogged idle jet. Low voltage will mess with Boyer timing curve. Valve adjustment & base timing need to be verified good. You may have multiple problems.

Morgo 750 kit will run perfectly with single carb & Boyer on 1970 Tiger. I know that for a fact from personal riding experience on a '70 Tiger with your set up. But... has new Premier as old was worn out. It starts perfectly also. Actually this is a very desirable combination.

Look into carb, air filter off. Hold full throttle. Verify choke is actually all the way up. Move lever & watch choke go up/down to be sure it's not binding.

How is valve adjustment? It must be verified good. That is a prerequisite.

Battery voltage MUST be 12.6v or more key off. Good voltage is imperative with Boyer.

Timing must be checked with strobe once you get it running. However, look at the Boyer install manual (on line if you don't have one). Set the static timing dot on rotor per the manual. This will allow bike to start & run even though timing is not perfect. If... you can't get the dot to show, you must remove pick up plate & rotate rotor on the exhaust cam taper. The Boyer rotor is not keyed to the cam like the original points AAU was. You have to mark where it is with felt pin. Pop it loose, then rotate in the direction where you run out of slot. Trial & error basically. A TDC tool is very helpful in lining up rotor & pick up plate. Or use timing mark on alternator rotor. Takes some practice & fiddling sometimes. Then after bike is running good enough set timing with strobe light. You may need to move rotor again if you didn't go enough the first time. Run motor at 4000rpm to read timing.

I like to set timing slightly retarded with strobe light. At 4000rpm the line on rotor ends up 1/64" towards rear wheel past pointer. That's about 36b. If timing is too retarded it makes bike hard to start & runs poorly.

After the Boyer static timing is set so dot shows as it should you're ready to start & see how it runs. Should start well & run decently if carb is ok. Even though you still need to do strobe timing after you get it running good enough to strobe timing.

Getting to carb, make sure no air leaks at intake manifold gaskets & carb gasket/o-ring depending on what you have. '70 Tiger would have had the fat o-ring set to air gap of
.040-.060". I like about .045". If you use phenolic spacer, make sure gasket is there on manifold side & skinny o-ring in carb groove. Whatever, no air leaks.

Set mixture screw 1.5 turns out. Slide 3 should work good. Needle position won't matter until you are under load & riding with throttle open enough to uncover the straight part. Main jet won't matter until 3/4 throttle or so. You may find the bike works better with clip on bottom groove of needle, but that won't effect your problem now. Verify the needle clip is indeed properly trapped under the spring & not winding up the spring.

Is this a new AMAL Premier or old original AMAL? The float level is different. Verify the float is not catching on anything. If you still have old plastic float & needle I most strongly recommend replacing both with Stayup float & aluminum needle with Viton tip. From AMAL. However be careful spending $ on old carbs as if slide & bore are worn it will never work right & die at idle. Still even with great wear it will usually start & run at least decently.

If all the above is good the idle jet & passages must be verified to flow well. To do this remove carb & remove bowl. Remove mixture screw. Remove jet holder, main jet & needle jet. Place plug in the idle air hole at carb mouth were air filter screws on. Put 2 fingers in carb & block the tiny fuel holes on floor of carb. Put stem of carb cleaner can into the passage under carb where idle fuel comes up through bowl gasket. Spray cleaner into hole. Cleaner should freely flow out of mixture screw hole, flowing through idle jet. Now blow cleaner through idle jet. Fuel should freely flow back into bowl passage. If nothing the jet is blocked. In any case take a piece of wire, strip it back 4" & cut 1 strand out. Look real close & stick that strand into idle jet. Make sure it really goes in through the jet. The jet hole is .017". If you can measure wire it must be thinner so can pass through. One wire is in wiggle it around to dislodge anything. Trial & error as you can't see or access the inside passage. Now blow carb cleaner into mixture screw hole, still keeping all 3 of the above passages still blocked. Use compressed air if you have it of course. Now blow carb cleaner through the idle air hole in mouth, the 2 small holes, the idle fuel hole on bottom & the mixture screw hole. Blow back/forth until you see all passages flow cleaner perfectly.

If crust is inside the hidden passage. Dry carb well as you can. Soak for 30 min. in white vinegar, turning carb & making sure vinegar is actually getting into the hidden idle passage. Flush with hot water. Compressed air if possible. Flush with carb cleaner spray again. If you get floating debris inside this passage you can finally work it out with vinegar & compressed air. I've done several.

If you have Premier carb the idle jet should be .019. The Premier has many changes & needs larger idle jet. Float level is above & parallel with float bowl gasket. Very different from 1970 Concentric which is .070" below gasket surface.

Generally if mixture is correct motor will start perfectly, but idle will be low & not reliable until motor warms up.

With a good tickle until gas flows down side of carb, no throttle, kick bike & as it begins to fire, give throttle & work throttle to keep it running until warm. About 10 min. The will idle fairly well & take throttle well. Choke is often not needed until you get down to the 30s. But when cold some choke will help motor take throttle better until warm.

Hot start is another matter. On warm/hot days bike may be hard to start after parking 5-45 min or more. The cure is tickle carb, hold full throttle & kick hard. Be ready to back off throttle as motor will rev fast. Will not idle until carb & motor temps stabilize. 2-3 min. Blip throttle. This is very common with modern fuel on old bikes.

If everything else is perfect. Mixture seems good. Bike wants to stall at stop lights or sometimes stop signs. Or wants to stall just taking off unless you give it more throttle than you'd like. Also sometimes in stop/go traffic rolling along at 15 mph or so traffic picks up slightly, you gently roll on throttle, motor hesitates or actually dies. Motor is fully heat soaked after 30-40 miles. You are stopped idling. You turn throttle very slowly lifting slide on a tiniest amount the motor dies. May or may not be hard to start under any of these dying. These are the symptoms of a worn slide & bore. Replacing slide may give some improvement or not depending on how worn bore is.

New Premiers work really well. Email AMAL directly. They will custom assemble Tiger carb with the slide, jets, top, banjo etc. you want. No extra charges. Many sellers have generic Premier that may or may not have what you need. You must verify from seller what slide, jets, including idle jet. Idle jets are visually identified by the number of grooves machined in jet snout. There is a chart to know what is what by the grooves. I would start with needle clip on bottom groove with new carb also.

Good luck on this. Can be a fight.
Don


1973 Tiger 750
Re: Hard Starting Triumph 650 [Re: tiger_cub] #781086 08/10/19 9:25 am
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Thanks all, I have good volts and valves. I will be checking the timing and changing as required, then will clean the carb


1966 Triumph Thunderville
1968 BSA B40M Roughrider
1970 TR6C
Re: Hard Starting Triumph 650 [Re: tiger_cub] #781331 08/13/19 1:46 am
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Today I will be checking timing & cleaning carb. Boyer instructions are conflicting in that one says timing is magnets align in centre of hole on plate, another states back edge of magnet aligns with back edge of hole, but Fig 2 diagram shows it on the front edge(?) which is confusing. Which is right? I will check and see where it is at least until I can work out correct position. Also, once running do the electronics then set the timing up exactly? Or is it not that sophisticated? At least the carb will be easy enough to deal with.....


1966 Triumph Thunderville
1968 BSA B40M Roughrider
1970 TR6C
Re: Hard Starting Triumph 650 [Re: tiger_cub] #781345 08/13/19 5:27 am
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Does the timing set up automatically?!!
The marks on the rotor are only to allow you to get it close enough to start.
You MUST strobe time the ignition to get it where it needs to be.


Stepping on others doesn't make you stand tall.

71 A65L "Zelda"
92 BMW K100rs "Gustav"
72 T120V cafe project "Mr. Jim"
72 T150V "Wotan"
Re: Hard Starting Triumph 650 [Re: tiger_cub] #781358 08/13/19 10:04 am
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I took the float bowl off and cleaned through everything, blew out passges etc. This carb has a horizontaly mounted pilot jet with 2 grooves, is this the Premier setup? I didn't remove the carb body itself although I may when i take the choke off as it doesn't really seem to do anything (it rarely gets below 19 C where I am). I checked the timing using the crank plug setting and was surprised that it was retarded by quite a bit. I set the magnet directly in the plate hole and tried to start, I don't have a strobe, I thought you couldn't use them with electronic ignition? and there isnt an access hole in the cover anyway. It fired a bit better, started after about fourth kick but still has a severe flat spot when I open the throttle when cold. Once warm it is fine. After warming up and a test ride I adjusted the carb, its responsive to pilot screw tuning but only 1 1/2 turns out, perhaps the bleed hole is partially blocked?, which i will check when the carb comes off. One thing I noticed in the Boyer instructions is that the coils need to be insulated from the frame - so how does the HT circuit work without the earth? I thought it went via the coil body. Anyway, it does work, the coils have had tape put round them to insulate from the bracket.


1966 Triumph Thunderville
1968 BSA B40M Roughrider
1970 TR6C
Re: Hard Starting Triumph 650 [Re: tiger_cub] #781363 08/13/19 11:25 am
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So you’re not going to set the timing?

Expect problems.


Amateur Loctite enthusiast.
Re: Hard Starting Triumph 650 [Re: tiger_cub] #781365 08/13/19 11:32 am
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The HT goes to earth via the ground strap on the spark plug, coil bodies do not need to be electrically connected to earth, The Spark is jumping from the HT live to the chassis earth via the plug earth strap, this is the small overhanging piece that sits above the centre electrode where the gap is.
Typically when static timed using the hole and the paint dot the timing will be too retarded, strobe timing is essential.
In case you missed it, strobe timing is essential.
I think this is deliberate, a too retarded setting is easier to live with than a too advanced, not the same kickback potential, although the bike will run when to retarded it will run hot and be down on power.
Strobe timing is essential.

Last edited by gavin eisler; 08/13/19 11:35 am.

71 Devimead A65 750
56 Norbsa 68 Longstroke A65
Cagiva Raptor 650
MZ TS 250
The poster formerly known as Pod
Re: Hard Starting Triumph 650 [Re: tiger_cub] #781370 08/13/19 12:15 pm
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tiger_cub Offline OP
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Thanks all, I know I will need to time it properly but for now my test ride was to give it heavy load and check for pinking, which there wasn't. I can possibly get a strobe but how to connect without interfering with the electronics, and what to time against in the timing cover - rotor magnet?? I know the HT goes to earth via the outer plug electode, but doesn't it need to make a full circuit somewhere back to the coil winding? I always thought this was via the coil body, but maybe I have been missing something all these years... Needless to say I am not an electrical engineer, but there must be a return path somewhere.?


1966 Triumph Thunderville
1968 BSA B40M Roughrider
1970 TR6C
Re: Hard Starting Triumph 650 [Re: tiger_cub] #781374 08/13/19 1:02 pm
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Originally Posted by tiger_cub
Thanks all, I know I will need to time it properly but for now my test ride was to give it heavy load and check for pinking, which there wasn't.


I would humbly suggest you need to do this AFTER it's properly timed with a timing light.

Originally Posted by tiger_cub
I can possibly get a strobe but how to connect without interfering with the electronics, and what to time against in the timing cover - rotor magnet?


Power the strobe using a separate 12V battery from the bike to avoid RF noise. Yes, use mark on rotor and pointer in primary cover to time...

Steve


'77 T140J
"Vintage Bike". What's in your garage?

"The paying customer is always right."

Fitting round pegs into square holes since 1961...
Re: Hard Starting Triumph 650 [Re: tiger_cub] #781411 08/13/19 8:32 pm
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Fuel flow should be around 300 ml/minute with the float bowl or float bowl plug removed.

I once meticulously cleaned a tank full of fuel that turned into a red gooey crust. Got the motor running but then it would not start. Turns out, the running of the motor dislodged more gooey crust that completely clogged up the petcocks.

Make sure all electrical connections are clean and tight. A dedicated earth from head steady stud to battery is not a bad idea.

What year is your primary cover? A 70 should have the port hole that enables strobe timing. Strobe lights are pretty cheap these days. Even I have one and I am cheap and broke smile

And, do yourself a favor and get a handful of #78 (.016") drill bits for cleaning out the pilot jet. They are small money.

Re: Hard Starting Triumph 650 [Re: tiger_cub] #781418 08/13/19 11:16 pm
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Thanks for all the suggestions. Unfortunately i have the earlier primary cover on mine, which is why i had to use the timing plug, at least it is closer than it was! Presumably I can use this setting and turn the plate until I get spark at least? No issues with the pilot jet it was very clean, I have never seen one that screws into the side before. I don't have a fuel flow issue as I replaced the old cracked fuel lines too.


1966 Triumph Thunderville
1968 BSA B40M Roughrider
1970 TR6C
Re: Hard Starting Triumph 650 [Re: tiger_cub] #781429 08/14/19 2:38 am
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Just started it after leaving overnight. Started third kick, had to use the jump on it technique to overcome kickback (milder than it was though) need to be careful with throttle but it idles OK after about 1 min now. Maybe there isn't such a problem now, will need to check/ re-set timing though


1966 Triumph Thunderville
1968 BSA B40M Roughrider
1970 TR6C
Re: Hard Starting Triumph 650 [Re: tiger_cub] #781433 08/14/19 4:44 am
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Originally Posted by tiger_cub
I know the HT goes to earth via the outer plug electode, but doesn't it need to make a full circuit somewhere back to the coil winding? I always thought this was via the coil body, but maybe I have been missing something all these years... Needless to say I am not an electrical engineer, but there must be a return path somewhere.?

The return path for the primary coil circuit is supplied by the closed points. In the case of electronic ignition the return path is supplied by a closed transistor switch.


Stepping on others doesn't make you stand tall.

71 A65L "Zelda"
92 BMW K100rs "Gustav"
72 T120V cafe project "Mr. Jim"
72 T150V "Wotan"
Re: Hard Starting Triumph 650 [Re: DavidP] #781496 08/15/19 1:01 am
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Originally Posted by DavidP
Originally Posted by tiger_cub
I know the HT goes to earth via the outer plug electode, but doesn't it need to make a full circuit somewhere back to the coil winding? I always thought this was via the coil body, but maybe I have been missing something all these years... Needless to say I am not an electrical engineer, but there must be a return path somewhere.?

The return path for the primary coil circuit is supplied by the closed points. In the case of electronic ignition the return path is supplied by a closed transistor switch.


Yes thats correct, but I was referring to the secondary HT winding


1966 Triumph Thunderville
1968 BSA B40M Roughrider
1970 TR6C
Re: Hard Starting Triumph 650 [Re: tiger_cub] #781501 08/15/19 2:10 am
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In an ordinary ignition coil, the LT and HT windings are connected internally at one end. This completes the HT circuit, with the engine/ground wires between.

Re: Hard Starting Triumph 650 [Re: tiger_cub] #783385 09/04/19 12:27 am
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Thanks for all the info. I have removed the choke parts as they didn't seem to make any difference. It usually starts second or third kick now, and I have to really be careful not to open the throttle too much in the first few minutes as it seems to starve and wants to cut out. I think this is normal? It idles OK after only a minute or so. I also tried to time the ignition by setting the crank position to the flywheel hole and then moving the points plate until I got a spark. Unfortunately it seems that it will only do this if its going at some speed, so a slow adjustment this way isn't really possible. Could this indicate a faulty Boyer or not? I think the timing is as close as its possible for me to get it, but a strobe is out of the question with the early cover I have. I am still getting a mild kickback on starting, but this may not be anything to be concerned about?


1966 Triumph Thunderville
1968 BSA B40M Roughrider
1970 TR6C
Re: Hard Starting Triumph 650 [Re: tiger_cub] #783392 09/04/19 1:26 am
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Your ignition timing is not set in such a way, and you're taking big risks with the engine.

Set the engine to the fully advanced position, take the primary cover off, make a clear white mark on the stator aligning with the rotor line.
In a dark shed, strobe at high rpm (somethng like 4000 rpm+) and adjust the Boyer plate till the marks align. Job done.
Ok, you may get some oil splattered about, not that big a deal compared with a wrecked motor.

Re: Hard Starting Triumph 650 [Re: tiger_cub] #783393 09/04/19 1:35 am
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Hi Tiger-cub, Get a degree wheel & the adaptor bolt set & attach degree wheel to end of exhaust cam. Make a pointer from coat hanger wire or the like. Put pointer under a timing cover screw. Set motor to TDC with TDC tool & put a TDC locater tool down spark plug hole. Set degree wheel to TDC. Start motor, rev to 4000 or until timing doesn't advance farther. Boyer generally is full advance 3500 rpm.

Read degree wheel half of what crank would be. 14b. I personally feel bikes work better on modern fuel 2 deg retarded. So I would use 13b on degree wheel.

This is not hard to do. However it is most important to get the timing correct. Static timing of Boyer could leave you 5deg+ ff or spot on. It is a pure guess. You can very easily hole a piston with guess work.

It is very to make a TDC locator tool from an old spark plug. Using grinder or lathe, cut the crimp off steel part where it holds porcelain part to steel. Grind off ground terminal the bent steel one). Deburr threads as needed after grinding. Knock the porcelain upwards out of steel body. Run 3/8-24 tap drill through plug body. Tap plug body 3/8-24. Get8-24 bolt about 2-1/2-3" long all threaded. This bolt will be the stop. Get a flat washer like a fender washer & nut to fit bolt.

With plugs removed turn motor to what is close to TDC visually seen through plug hole. Fit degree wheel to DTC (degrees). Back off piston about 1/8" or so.

Screw nut up to near 3/8 bolt head. Slip washer on bolt. Screw bolt into plug body until it lightly contacts piston. Snug nut/flat washer to plug body so bolt is held steady & can't wobble in threads.

Now you need to pay attention. Turn crank via rear wheel in 4th gear GENTLY until piston contacts bolt tip & piston is pressing against bolt tip. Read degree wheel. Back crank all the way around until piston contacts bolt tip again. Read degree wheel. Add the degrees total movement & divide by 1/2. Move degree wheel by that number off degrees. Now repeat the turning motor back/forth until piston contacts bolt tip. Keep adjusting degree wheel until the - & + degrees each side of zero are equal.

Practice this until it makes sense & you understand what you are doing. When practicedit will take only 2-3 attempts to get reading equal each side of zero. Make sure the degree wheel spindle is tightened onto cam well. Tighten degree wheel to its spindle well so the degree wheel doesn't slip.

This will be very close to zero, nearly perfect. Possibly a tiny back lash error, but don't worry about that. Remember there is a tiny bit of play in the TDC tool also. So it's a wash.

Put spark plugs back in.

Now start bike & read with strobe light. Move the pick up plate as needed to get timing correct. If you run out of slot on plate, mark the rotor with a felt pin. Remove degree wheel loosen rotor & turn it slightly in direction you run out of slot. Sadly you now need to reinstall degree wheel, set it to zero & check strobe again.

This is part of older Triumph ownership. Just the reality of it. Short cut or guess the bike will screw you.

That covers timing, which is a prerequisite for any other tuning. Of course valve adjustment must be correct also.

Sounds to me you are still a little lean at idle circuit. I feel it will never be right with a 2 ring .017 idle jet. Yes it's premier. You need a 3 ring .019 idle jet. Every premier I've been involved with needed a 3 groove idle jet to run properly in all conditions. Yes you can get away with 2 ring, but I feel the extra cost of 3 ring is worth it.
I would recommend moving needle clip to bottom groove. This tends to give a little more cooling & richness right where you need it on the transition to the needle taper. A lot of pistons get holes burned in them right there.

The bike should almost always start first kick & almost never want to kick back. A tiny bit of clutch slip will cause kick back & harder starting, yet you may not really feel it riding. If you sometimes hear a tiny squeak during kicking that could be clutch slip. This can be very hard to diagnose. Unless you feel slip riding just set on this thought. Clutch should never ever slip while riding. Not even a trace should you feel. If you do, start by tightening springs. There is a formula for that for later if needed.

You are correct, generally use zero throttle until starting, until motor fires. Owners manual says slight throttle, but most find that doesn't work well. Hot start is different.

It cannot be overstressed how important it is to get timing checked & set by strobe. This is your next step.
Don


1973 Tiger 750
Re: Hard Starting Triumph 650 [Re: tiger_cub] #783410 09/04/19 7:16 am
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I like koan58's method above apart from the obvious dismantling required. Don's explanation left me with some doubts ie won't the centre rotor be disturbed when its bolt is removed & replaced? Possibly I could rig something up to do this? I would consider going back to points if I had the parts, easier to set, but I like the tip about the 3 ring pilot jet. Is it confirmed that the Boyer won't spark just being turned slowly?


1966 Triumph Thunderville
1968 BSA B40M Roughrider
1970 TR6C
Re: Hard Starting Triumph 650 [Re: tiger_cub] #783416 09/04/19 9:01 am
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Warning. Kickback is a red alert.

Possible causes:
Incorrectly set timing.
Voltage drop feeding the Boyer box.
Reversed wires from the Boyer pickup.

Re: Hard Starting Triumph 650 [Re: tiger_cub] #783422 09/04/19 10:17 am
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The Boyer instructions only get you to a point where the bike will start and run.

Pull your primary cover off, mark the rotor and strobe time it at full advance.

Go back and read the posts from Koan58, tritonthrasher, DavidP, TR7RV, JubeePrince etc. they all say the same. Strobe time it at full advance.

Then start mucking around with carbs and coils.


'51 C11 in a '54 C10L frame..."The Bantam Eater"
'70 Triumph Trophy 500. Bottom end rumble awaiting diagnosis
'72 Triumph Tiger 650. Back on the road...
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