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#825935 10/07/20 10:31 pm
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Hi all. 66 Lightning, standard bore with the EV pistons and gapless rings. Standard everything, including correct left and right Monoblocs. I installed the later year points plate 6CA, and ACU instead of the 4CA. The bike has the proper cover on the primary side, so I have no access to strobe timing. When I assembled the engine 1000 miles ago, i set the timing with a dial indicator on the piston tops. Engine starts easily when cold, 1-2 kicks closing the air control. I do not tickle unless really cold outside. (winter in NJ). On a hot day, the the engine sometimes varies idle speed on its own but not always. No detected vacuum leaks. I set fuel level to the "pip" on the fuel bowl cover using a clear hose. I had the monoblocks sleeved and I installed all new spec sized jets and needles. Pretty happy overall. Happy to report NO oil leaks. A little trans fluid leak from the kickstart shaft and gear selector shaft.
However, on medium grades 50mph i can detect pinking. And pushing 70 mph for extended time on the interstate, I get the feeling the bike is slowing down with steady throttle, and I need to twist open a little more. Fuel flow thru the fuel taps appears fine. Playing with the choke position seems to be inconclusive. Full choke, does cause the engine to bog. I have already retarded the timing, from what i set during engine rebuild, but not retarded by a measured amount. I merely rotated the points plate abit to retard. My question is, should I have larger main jet than the spec 270 because of the 10% ethanol in our fuel? I do fill with premium. At 69 years old, i dont feel comfortable doing high speed wide open spark plug checks like I did 50years ago with my 68' lightning. I have to believe there are other "stock" 66 lightnings with a successful tune they can share. Thanks for your help.


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One for debate but i tend to err on the safe side myself as fuel around here can be iffy.
32-33 btdc and a 250 main in my t'bolt, needle on centre groove. I'd rather be a bit on
the rich side than seize the old crate.

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I would keep retarding the ignition ever so slightly until the pinking stops when you are riding up medium grades at 50mph.

Might also be worth trying a premium fuel with a higher octane rating or adding a an octane booster to the tank.

Quote
pushing 70 mph for extended time on the interstate

These old crates don't do too well at that kind of extended speed and it may be the slow down is the engine partially seizing? If I ever ride at 70mph or above, its not for long and I usually back off to the normal cruising speed of 55-65. I think these bikes prefer being ridden on non interstate roads, up and down the gears and throttle on/off.

I would consider fitting an EI system which will at least ensure the spark is accurately timed on both cylinders.


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Quote
And pushing 70 mph for extended time on the interstate, I get the feeling the bike is slowing down with steady throttle, and I need to twist open a little more.

So you are not a full throttle when you get this slowing down feeling, better to raise the needle than change the main jet as a quick way to see if the bike runs better. Much better in these early days to mark the throttle at 1/4, 1/2 and 3/4 open so you know what the throttle openings are when you get odd symptoms, that will tell you which part of the carb needs tuning.

And you must strobe the engine, timing the engine statically is just so you can get it started not for long term use.

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nert #825959 10/08/20 11:01 am
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Two things. Sometimes the advance springs do not control when things happen. The modern electronic ignitions have a more sympathetic and reliable curve. If you keep retarding it will just overheat quicker. Get a later primary cover at a swap meet or borrow one so you can set ignition with more certainty and the put the correct one on. I never got my A65 ping free on pump gas but with a bit of leaded race fuel or av gas she ran sweet..
My 2 cents, PRT

PS Do you know what your piston clearance is? Another Jersey guy.

Last edited by pushrod tom; 10/08/20 11:28 am.
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nert #825964 10/08/20 12:08 pm
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adding to PRT's comments,

I found stock auto advance springs go full advance about 2000 rpms, I always found this too low in rpm for full advance. If you get some springs from EuroJamb.com I have found they will go full advance at 3000, with a tweak of the springs it'll be 3500-4000rpm (depending how much you tweak them) I found this helped massively when I ran points on mine as regards pinging and meant I didn't have to retard the fully advanced position.

Also are you strobe timing the bike? If your using the 6ca points.... This is a must for both cylinders as they are tunable independantly unlike the 4ca unit.

Last edited by Allan G; 10/08/20 12:09 pm. Reason: typo

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Nert,
I am just down the road from you in Ewing. I have a '66 Spitfire with 9-1 pistons and I have also put the 6ca points on. I don't strobe time either. I use the plug on the front and I am careful with a continuity light. The first few times I set it up this way I checked with a strobe and found I was right on the money, so I don't bother checking any more. Mine doesn't pink unless I lug it. There can be a lot of issues with setting timing with a dial indicator (the method used to find TDC being one of them), however, you sound like someone who knows their way around these engines. What do your plugs look like and what brand of gas are you using? I would try: 1) Get yourself some 100 octane airplane gas (I get mine at Robbinsville Airport), if the problem goes away it is probably carburation; 2) Raise the needles; 3) reset the timing using the plug in the front and a continuity light.

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may i suggest the following.
Remove primary case, set motor to full advance using the crankcase timing plug/ flywheel notch. Draw a line across the rotor and stator with white paint/ correction fluid, strobe test with the cover off.
Pinking can be provoked easily at around 3,000 RPMs, some stuff that will help, remove sharp edges from piston valve cut outs during build up.
Change down when accelerating on hills.

Feeling the engine falter at 70 mph may be excessive richness, try the needles one notch either way and note which gives best performance.
Do What Kommando says, mark the the throttle drum so you know exactly what position this takes place. Main jets only make a big difference above 3/4 throttle, yeah they overlap a wee bit lower down , but needle position is much more influential
Your bike should be cruising happily at 65 -70 with not much more than a 1/4 throttle. This is just over 4K on std gearing 20 /47. Which is pretty much the sweet spot for these motors.
if you are using 21 / 47 you may be lugging the motor at 50 MPH on a steepish hill.


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Thank you, all good solutions. Almost embarrassed to say, but I don’t own a timing plug.
I am very fond of points ignition, and will probably never change it out. I resist strobe timing because of the oil, gasket mess I need to deal with when changing covers. The rotor is properly marked, and I have a used cover with the window if I decide to strobe time. I would then reinstall the windowless cover, as I prefer the look. Good suggestion about marking the throttle. That idea has been around for a very long time. I have never done it. I will “To measure is to know.” The advance springs make a lot of sense, I never gave them much thought before. I don’t recall the piston clearance. It is an old used standard bore cylinder. I added a nice slow turning 45-60 degree crosshatch with an old Sunnen rigid hone. I took notes (scratched some numbers down somewhere). I would not have run with it if it was too tight or too loose. Edunham, does the airport in Ewing have the proper fuel, and if so why don’t you purchase there? And yes, 65-70mph is just around 4k rpm. Obviously, there is a little needle dance on both instruments. Same speed the mirror almost becomes usable again. Thanks again.


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nert #826087 10/09/20 11:09 pm
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yeah... put some 100LL Avgas in it. even 20-25% will make a difference. it's 5 bucks a gallon but old engines love lead. btw, 100 low lead isn't very low, it has about 4x as much TEL as the old 87 avgas had

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I don't think lack of/or presence of lead makes much difference. The gradual increase of ethanol content does make a difference, though apart from destroying my fibreglass tank, E5 hasn't resulted in any obvious changes to my engine yet.

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Contrary to popular belief, lead is not a combustion improving substance.
If the MON or RON rating of the fuel used is as specified in the bsa book
the motor will be fine when run on it, if the motor pinks or pings, then
something is amiss/

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I deleted my post. I'm sufficiently embarrassed by my lack of correct memory on this subject.

Sorry gents

Last edited by mxman1; 10/11/20 4:32 am.
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Wouldn't you get more dwell with smaller point gap?


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Yes.

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I placed the tape on the throttle grip. Forgot about parallax view. I will have to re-mark it. However, as was stated previously, 55-60 mph reveals 1/4 or less throttle. I retarded the timing a little. Without strobe, just rotated the point plate counter clockwise a little. Took it for a brief ride. First ride impression, Acceleration is better, I "think" the pinking is less if not gone, idle speed is smoother and more stable, maybe even less vibration at speed. AND now, the clutch is slipping after i up-shift. Could be the "stronger" running engine is slipping the clutch? Clutch cable has clearance, I will have to check my pushrod clearance next.. A 6 mile quick run is premature to make a definite claim for success. Rain is coming for the next few days. Looks like Wed is dry, but 45 degrees at 6:00 AM for 30 miles to work is COLD on a BSA.

[img]https://www.dropbox.com/s/8m5mdqbalvuryo2/IMG_5994.JPG?dl=0[/img]


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Glad to hear its running better, regarding the clutch make sure you are using a 'classic' car oil or wet clutch friendly motorcycle oil in the primary.

Suitable classic car primary drive oils include straight 30w or 20w50 both of which should have an API grade of SG or lower, these grades dont contain friction modifiers which can cause clutch slip. Motorcycle oils should have a JASO MA grade which is wet clutch friendly. You can also use ATF as long as its type F which is also wet clutch friendly.

Using more modern oils without these earlier grades will almost certainly cause wet clutches to slip as they contain advanced friction modifiers.


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Nert,
Last time I tried, I was unable to get gas at the airport in Ewing. Its easy at Robbinsville, so a couple of times a year, I go over and fill up a couple of 5 gallon containers. I have one of the timing plugs somewhere, but I rarely use it. I just stick an allen key or a screwdriver in there to catch the hole in the crank, and then make sure the hole in the crank is centered in the hole in the crankcase. I like points also. Some folks lock the advance unit at full advance to check timing. I do not. I put the crank in the correct position and then with my continuity light in place, i use a screwdriver in the notch on the points cam to turn it to full advance. The idea being that the light only goes out just as the cam reaches full advance. By the way, from your description, it almost sounds like you advanced the timing slightly!

Ed from NJ

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The points cam is on the idler pinion, this rotates anti clock , if the points plate is rotated anti clock it retards.
If the clutch is now slipping you have found more power, check push rod end play ASAP. if thats OK you may need a turn more on the springs.


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gavin.

That's exactly what I thought. I found more power!! The clutch slip could have been hinting at a clutch problem when I was loosing speed at extended highway speed against the wind.

Last edited by nert; 10/12/20 10:34 pm.

keep your "oddies" lubricated, and carry a dime

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