hi

im trying to help a friend who has got a lightspeed 2 - he got it from new and when he first got it it would easily do 70mph but now it wont go above 55 - when he gets to 55mph it sort of feels like the brakes are coming on ever 2 seconds and then relesed again - its a sort of julting movement. Any ieas - i have had the carb out and cleaned it all - the plugs in nice and tight - theres clean fuel in there - and now im out of ideas