I've been trying to trace down my bikes starter clutch bang for some time. It has a new starter clutch. that bit all bits fine.

If I spin it over with the coils disconnected its fine, churns over no problems. With the ignition on it very often, bangs or baulks and the starter stops. press the button again and it'll usually catch.

I spotted that there was an issue on another GS with the ignition timing causing issues and a dubious looking lever being added to manually retard the timing for starting.

I wondered if this was the problem i was having - the ignition firing too early and driving the engine backwards under the low-low starting speeds and causing the starter some hurt.

Cover off. hmm.



and what is this? Found loose at the bottom of the housing.



What it looks like to me is that snapped off pin has advanced the ignition a little bit. and thats what is causing my problem.

The pin would seem like it should live



in the 2 o'clock hole. But the bit end appears snapped so i dont know if its part of a longer pin. Predictably the signal generator screws (screws!) are a bit tight and i don't want to force them to get better access.

Update:

Signal cover off, if it is part of a larger pin I don't think its coming out...

thoughts?

JB weld the pin back into place and hope the bolt tension keeps the rotor aligned correctly?

I think you're right about the pin but I think a better solution would be to remove the remaining but and replace it properly.  Without researching more (maybe I'll have time later) you could maybe drill it, thread in a screw and pull the pin out. 

Does anyone here know if this pin is in a blind hole or a through hole?

That missing pin would certainly throw your timing all over the place. A couple of revolutions with ignition way too advanced can finish your engine off for good.

I'd be hesitant to use JBweld as I don't think it will get a strong grip on the end of the crank.

+1 on the drilling -  i would drill out the pin (starting carefully and going slowly with a small cobalt drill and going larger and larger till you can fit a new pin in place ). The drilling might make the pin come out half way through.

Looking at the gouge mark on the bottom of the rotor, seems it was bolted down onto the pin off-centre causing it to crack and break.

Obtained a 2nd hand rotor and bought a new pin.

I should be able to work out how much is left in there comparing the stub with the new pin then go from there.

I am sceptical about drilling it. Its a hardened pin and so small that its hard to get a good start on it, I do wonder if i could get a mm or two in wether banging a torx bit in would be enough to spin it free. Exploring some other options. someone suggested welding a coat hanger to it but I think thats a bit last chance saloon. I did contemplate welding a ridge onto the end of the crank but I really doubt it'd get it right. or i'd wreck the crank.

more to come.

If you can get a center punch mark into the center of the remnant of the pin, then a very small drill bit and some care should be what it takes to get the pin out. Start with the smallest drill you can, like 1/2 the size of the pin or smaller if possible and go slow. Then progress up in size of drill in tiny increments until either the pin remnant comes out, or you have a hole big enough to put a #4 tap into it (assuming that pin is substantially bigger than a #4 screw), then put in a #4 screw through a 1/4" socket and washer stack, pull the pin by driving the screw in. If that doesn't work, maybe try a slide hammer.

I have a whole lot of other ideas on how to deal with this but I'd be worried first about why this pin sheared in the first place.

Well now, I have my sneaky suspicions that the shearing might have been me all along...

Not being aware there was such a pin I may* have tried using the rotor bolt to steady the crank whilst I undid the generator rotor on the other side.

I foolishly assumed it was fairly sound since you can turn the engine over with it.

I'll wait and see what the pin looks like when its not broken - if there is loads in there i'll consider drilling it but if there is very little i might just JB weld it back in clamp it down and never use the rotor to turn the engine again.

lesson learned though which is the main thing...