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Motorcycle Tech
Motorcycle Tech, Motorcycle Mechanic
Category: Motorcycle
Satisfied Customers: 1306
Experience:  Motorcycle Tech
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2 stroke motors and they both sputter at high rpms and they..low rpm

Customer Question

I have two Yamaha pw80 yzingers and both are 2 stroke motors and they both sputter at high rpm''s and they both spit out alot of unburnt oil out of the spark arrester. they both run good at low rpm''s I have changed the plugs and also went to a hotter heat range plug and no change in the problem. I don''t where to start to fix the problem. thanks
Submitted: 8 years ago.
Category: Motorcycle
Expert:  Motorcycle Tech replied 8 years ago.
You could have a pluged EX Pipe Silencer ... they plug up with carbon real fast ... there should be a small screw in the bottom of the pipe at the end .. remove this and pull the Silencer out and clean it ........also some PWs had a rev limiter in the EX pipe....just where it bolts the the Head ..its a small washer with a small hole in it ...restricting the flow of EXhaust .... removing the washer can help... but I would go back to the cooler plug if this is the case...
Customer: replied 8 years ago.
Reply to Harley Tech's Post: The first thing I did was to pull out the sparkarester and cleaned it and no change in problem then I changed the spark plug and no change..I took the pipe off and there is no washer just an exhaust gasket. So I took off the pipe on my other pw80 and there is no washer I cleaned the pipe of all unburned oil and reassembled it and no change in problem.. So I guess I'll have to wait for my manual to troubleshoot this proublem or figure out some way to disengage the rev limiter or something..    thanks for your help anyway..
Expert:  Motorcycle Tech replied 8 years ago.
Thank You for using JA