robin i would do two things firstly i would set the valve clearances to .08 on the inlet valve and .12 on the exhaust valve.then i would try this find the caburettor usually under the seat bucket on a scooter then take the top off the carb the metal part,then you will see a rubber diaphragm and a slide in the middle of it pull this out and you will see a needle sticking out iof the bottom of it inside the middle of the slide you will see a clip holding the needle ina and maybe a plastic spacer that the spring rest on take all this out but make a note of the order they comeout in ,then take the needle out and you will see a circlip in a groove on it pull the circlip off and move it to the end slot nearest the pointed end of the needle doing this will richen the mixture and mabe solve your problem as it sounds like its running weak .good luck with it and the thanks is always worth saying we all appreciate it.
adam bike doctor, August 2010
