[kwoolard]

A friend of mine is having trouble diagnosing why the engine bogs down when you give it throttle. He has replaced all fuel lines, new fuel and plugs and has rebuilt the carburetors. The motor idles fine but bogs when given any throttle. Could this be the reed valves or do you think it is an electrical problem? How does this motor advance the timing?

Thanks

[kwoolard]

Anybody have any ideas? I was thinking a stuck choke, leaking or faulty fuel pump, or a bad reed valve. I am not familiar with the Yamaha's, and I haven't looked at the motor yet, just trying to get some ideas on things I should check when I take a look at it this weekend.

Thanks

[bgbass.1]

also check wher fuel line plugs to motor o ring could be no good and sucking air

[JUSTINTIME]

bad gas?