raining-fish

got one this morning {ebay} many dollars! but, success! cdi fitted and easy starting accomplished! brrrum! the only thing i can think of with the last one was it must have been sparking much later than TDC- hence all the backfires! thanks for your help.

it looks like, after a trawl of the internet, the CDI unit of a yz490.

nope, it wasn't that...b****r! when i kick it over, smoke comes out of the exhuast, but still no starting! i,ve just noticed that my CDI has eight wires coming out of it where-as the manual only shows six. there is an extra black and a white and green{striped} un-used wires. it is a mitsubishi one, perhaps off a later model? time for a beer?....oh yes.

i put my thumb over the spark plug hole and turned the engine over- virtually no compression! the head and barrel are off now but the piston looks really good and the rings are nice and free. while i was sitting there feeling puzzled, i saw that the decompressor valve doesn't seem to go back all the way in when the kickstart returns to the top. so a quick rebuild {again} and we'll see what happens.

did you ever find out what the problem was? i have EXACTLY the same problem with mine and have tried the same fixes too, but with no luck. the bike will run {a little roughly} over 2500rpm but dies below this. also many backfires when using the kickstarter. i have tried everything i can think of without taking the piston out. carb-many many cleans, air filter fitted and not fitted, timing- all positions, exhaust is nice and free flowing with no holes, spark plug, cap and ht coil all replaced, crank seals-replaced, decompressor- checked and properly setup. still no solution. anyone got any more idea's? fuel is getting in and it is sparking, but it still won't run. i'm thinking about taking the piston out next to see if the rings are stuck in {the bike has been standing for a couple of years}, failing that.... dunno!