Hi all,
Firstly thanks to everyone on this forum that helped me get the bike running in the summer, your advice was invaluable. As it turned out the bike was fine it just needed the right CDI, which eventually turned up on ebay.

Anyway currently the bike is poorly again and I'm not sure what's up. It has just been set up on a rolling road and was running beautifully. Whilst out for a ride it sounded like it dropped a cylinder and it was a nightmare to nurse home.

I've had the diaphragms off the carbs and there appears to be tiny bits of black rubber floating around in each carb. Could these be clogging up my jets and preventing the bike from running and starting properly? or could it be something else? I am assuming the rubber bits are from the o-rings but these have not long been replaced, any ideas as to how or why they might be shedding and why the bike was fine until I really opened the throttle.

Any help you guys can give would be greatly appreciated as it does seem that this forum is the only place to get reliable technical information about these bikes.
Thanks again

Never seen or heard of the o'rings shredding, can you post any pictures.
I would think its more likely bits of diaphragm.

Or it could be bits of crap from the air filter moulding, even genuine OE filters have bits hanging off them from the moulds. I'd clean out all trace of them and see how it runs.

Hi, just thought I'd let you know what's been going on.

I had the carbs apart and on 2 of them the o-ring around the main jet holder had been cut by the thread as the main jet holder had been screwed back in. This was where the bits of rubber that blocked the jets were coming from.

I have now replaced all the o-rings (again) and the bike appears to be running properly on all 4 cylinders (it did, however, overheat on the test ride and dump all it's coolant all over my left leg. Nice).

Anyway thanks as always for the help and suggestions, now all I have to do is redo the coolant system and we're there.

Make sure you bleed the water pump after filling up the rad as it airlocks and then the bike dont cool properly.