Ignition Problems A65 Spitfire

[Tim67]

Hello fellow BSA Owners,

This problem has got me stumped!!!

Yesterday i started my A65 for the first time since laying it up for the winter - it started, but was running rough (backfiring) and wouldn't idle. I retarded the ignition by rotating the Boyer Stator (anti clockwise) to its fullest extent and the bike ran smoother (but still didn't idle properly). Thinking the plate with the boyer magnets might have slipped decided to completely reset the timing and clean the carbs.

First i removed and cleaned the carbs (which didn't look all that dirty). I have premier carbs so i could get at and clean the idle jets. In the float bowls there were only minimal deposits.

Then i removed the Boyer Magnet plate from the crank, found the slot in the flywheel (which is 34 Degrees before TDC on the compression stroke of the timing side cylinder) and then refitted the magnet plate such that it was in the middle of the adjustment range of the stator plate.

During this procedure i also removed the rocker cover to check that the position of the rockers corresponded and that the piston was indeed just before TDC. Sparks are good on both cylinders.

Tried to start the bike on my paddock starter - nothing!!!!

I have checked everything three or four times and am now at the end of my tether.

Does anyone have any suggestions as to how to go forward from here?

Thanks!!

[MartinW]

You didn't forget that A65 cam rotates anti-clockwise?

[JulianS]

Suggest you refer back to the Boyer fitting instruction for your system - they are available on the Boyer website if mislaid.

With piston in correct position you need to align the red dot on the rotor with the appropriate hole in the stator plate and when started check timing with strobe light and adjust as necessary.

Make sure battery is well charged, low volts can cause problems.

[Tim67]

Hi, thanks for your answers to my post!

Yes i am aware that the cam turns anti clockwise and that the red dot must be visible through the hole before the coil in the direction of travel.

What i might try now is to swap the wires to the stator around (i removed them earlier), although i cannot see what difference it will make as the boyer system is - as far as i know - a wasted spark system meaning that the the spark occurs twice per cycle in each cylinder.

Will post the result of swapping the wires around.

[Tim67]

Well, i swapped the wires to the stator around and i have a running engine again!

Can anybody explain why? I was under the impression the ignition system is a wasted spark system.

[Shedman]

I believe that if you swap the wires it retards the ignition timing. As for the running rough after being laid up for a while i had the same problem with the boyer on my bike and found that if you remove the points cover and blow the stator coils gently with a hairdryer or heat gun it will dry out the dampness in the coils as they tend to draw in moisture whilst stood.This always cured my problem.

[ChrisG]

Great Tip Shedman, Can I use this in The Star?
Chris

[Shedman]

Yes no problem