40 yamaha 3 cyclinder (2 stroke)

[Kamdyn]

I am trying to pin point my problem, My motor is fouling plugs. The motor requires BR7HS-10 and thats what I am using. Am I not giving it enough time to warm up or do I have a dirty carb? I recently did a compression and I got 120 on all 3 cyclinders so I ruled out the piston. By the way I am new to the forum, Thanks for having me. I been peeking around and you guys sure know your stuff. Also I havnt figured out what year the motor is?

 

[robert graham]

Re: 40 yamaha 3 cyclinder (2 stroke)

Is your gas fresh and your fuel mixture correct? If your motor is running "cool" and not getting up to normal running temperature in the 130 to 170 degrees F. range caused by a stuck thermostat or other, then it could cause a rich mixture situation and fowling plugs. I use the Pennzoil 100% Synthetic Outboard Oil and the plugs burn very clean. Also, if your fuel pump was going bad it might suck excess fuel into motor causing plug fowling. Is you motor running well throughout the entire RPM range? Good Luck!

 

[Kamdyn]

Re: 40 yamaha 3 cyclinder (2 stroke)

I just spoke to the shop that I bought the motor from, They told me it can be a number of things wrong and I should bring it in. I got enough headaches with this motor, Thanks Graham for your help. ill report back with some answers that solve my problems