Originally Posted by culliganman
Ready to pull my hair out!
Bike is running very lean, happened all of a sudden have had the carb apart 3x to no avail, boots look good you could eat off the carb its so clean. What are the odds the timing chain jumped? I do notice a air blast,poof type sound when starting it that seems new if that makes a difference not a backfire its coming from the motor somewhere.
How do you know it's lean?
Do you have fuel filters? Could there be some debris in the fuel line, fuel valve or needle valve? Have you blasted carb cleaner through all the carb passages and jets or does it just look clean on the surface? Have you checked for water in the fuel? (drain the carb bowl into a white container and look for beads of water running along the bottom)
Are you sure the spark is ok? If I were to suspect something that seems like lean but isn't, I'd look at that before suspecting timing. Have you checked compression? A sticking valve or broken ring would lead to an air blast sound as air escaped past the bad seal.