A friend of mine brought me his SC28 900RR As it would not start and although its a long story, I'll give you the bullet point version.
18K Only bike obviously been stored and very nicely for a long time. My mate has ran it for about 600 miles since he bought it and one day he went out and it went onto reserve (or so he thought) so he filled it up.
Shortly after it stopped and was making a funny
He brought it to me and it would not start it would fire with some easy start but not run.
Took the airbox off and it was full of corn seeds
at least a couple of cupfulls and the air filter paper had been chewed.
Removed all this but the corn had not penetrated to the engine side.
Still it did not start and was puffing smoke out the exhaust and occasionally backfiring once every so often.
Long story short, going through everything i eventually took the head off and replaced the head gasket, checked the valves in the head with it upside down and filled with fuel. (all seemed ok.) Suspected a broken head gasket and replaced it rebuilt it new plugs filters valves set and it all ran fine.
Guy came and picked it up and although it appeared to smoke on the overrrun it ran ok. He took it home and two days later it would not fire again. Similiar backfiring every so often but wont run.
Checked everything again, carbs floats, diaphragms, cam timing , battery compression (175psi),so i replaced the spark plugs with old ones and it fired up and ran. A replacement set of plugs
fired up ok.
Two days later same problem wouldnt fire.
Checked everything again and in desperation replaced the igniter coils and ignition box and still would not run.
Replaced the spark plugs and it fired up.
Took it for a 40 mile run all seemed ok but it still smokes but only on the overrun.
four days later it wont start again, its pushing greyish smoke through the exhaust whilst turning over but it wont run just backfires every so often.
Checked carbs, all clean checked sparks and timing all seem fine, only common thing is the plugs get black and sooty/wet.
Told to check the float heights again but they are not adjustable anyway.
Any ideas or help appreciated as this one has me scratching my head. (the only thing ever I have had so many problems with is where a zx9 bike had worn out valve seats.)
What do I try next?