its a four stroke stroke isnt it ? if so then the valves will have tightened up on the clearances i bet it very common and also they have a restricter in the top of the carb that stops the slide from lifting up
adam bike doctor, November 2009
I'd say more than likely that the exhaust is probably stuffed with waste two stroke oil. Only cure is to unblock the exhaust by taking it off & putting something like caustic soda down it. This will soak up the oil & get blown out through the exhaust once it's back on the bike with the engine running.
If you don't fancy doing it yourself, I'm sure your local bike shop will only charge a small fee for this job.
