We just swapped out the stock engine on a '92 Blaster for a '97 Blaster motor. The reeds, carb, etc are all off the '92. Once started the engine will rev, almost race, to a very high RPM after one blip of the throttle. The air box is disconnecte b/c we're just testing everything is together. Any explanations or investigation tips?

 

is the throttle sticking at all. If so unscrew the cap off the top of the carb and give everything inside a good spraying. If the throttle isn't sticking the idle may need to be adjusted. If all of this fails take the whole carb apart and clean it.

 

Its either lean or your piston is backwards. What color is the plug?. Did you take the engine apart at all? I would check the reeds first just to make sure they didnt break when you switched them out. Make sure the carb boots are good and tight. Make sure the base gasket isnt leaking. Iv also seen a cylinder crack and have the same problem.

 

Make sure the cap on top of the carb is tight. An air leak will cause an engine to rev up. Saw this happen many years ago on a friends Blaster.

Daren

 

Air leaks cause 2 strokes to race to the moon

 

Thanks for the replies. I'm going over everything to check for air leaks. Found a slight gap in the reeds on one side - they should always lay flat, correct?

 

Yes