Curvy running on one cylinder.

Hi, been having problems with my y model 650, a week ago it started dropping down to one cylinder, usually half way round a junction or somewhere equally useful, now it is constantly running on one. had the carbs off and cleaned the jets, all fine, fuel pump is supplying loads of fuel, that spark plug is sparking and the air filter looks fine, worried its something internal now, any ideas gratefully received, thanks

[rictus01]

have you checked the "usual suspects" yet?

although possible; it's not normally a mechanical cause, check out water ingress first, electrical continuity, fuel & air , then if all that is correct, valves and then move on to compression testing.

Cheers Mark.

[embee]

Originally Posted by rictus01

have you checked the "usual suspects" yet?

plus check choke plungers are properly free in the carb bodies, return springs are good and no sign of corrosion/gunge in the cables.