mmmmmmmmmmm i just realised you said it revs ok when you lift the back end up,this may be due to either the fuel in the tank being available to the carb when you lift it up of it could be that the airfilter intake is blocked when you sit on it and not when your not sitting on it.has it got lots of fuel in the tank i would aslo check the carb for water as i have said as it may be that the water runs away from the main jet when you lift it up at the back.
adam bike doctor
February 2010
it means its running weak and there is a shortage of fuel in the fuel/air mixture so maybe it has some water in the carburettor or the main jet is blocked i would say the pilot jet was ok if it idles fine.has it been stood for a while?or just like it all of a sudden.also the inlet manifold/carb or gasket/oring may be damaged or loose.Is the airfilter box secure and in good condition with no air leaks?
adam bike doctor
February 2010
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