Hi my sons DNA 50 GP Experience won't rev past 8000RPM and consequently won't accelerate properly. All of the usual things have been checked; timing, mixture, spark plug, fuel flow, carburretor has been cleaned and settings checked. The only non-standard thing is the exhaust but we have replaced this with the original to no avail.

Steve, June 2008

its probably a carb set up problem

cdi unit will be fine

could be pistone rings but i doubt it , as ive replaced mine and its doing the same as yours

I can only get 38 down hill and im lucky if i get up some hills , lol


what size jet have you got ??? 56 is standard ,, ive upgraded to a 60 to go with an unrestricted exhaust

but thats still poor performance

but a 70 jet gets me more power

also old belts stretch when they get warm
a new belt will have about 1 inch less slack

jason, August 2008

Its a Two Stroke, so you need to lift the head and barrel and DE-COKE it. In other words carbon build up in the exhaust port is restricting the engine.

Could also be worn piston rings/barrel.

Steve, June 2008

it has a rev limater in the cdi n change the rollers if u havent done this yet

richard, June 2008

Good one!!You did look down the carb intake to make sure that the throttle cable is fully lifting the throttle slide?also ,when switching the exhaust was the gasket correct,oversize could give symptoms u state,ie blocking gas flow.thats how they retricted early putputs.

caine, June 2008