1987 Yamaha 40hp Spark Issue??

Drowned Rat

Captain
Joined
Jan 20, 2004
Messages
3,070
Morning everyone,

I have this older engine that appears to have very few hours on it. It a manual start 40hp 2 stroke short shaft, tiller. Starts right up easily. It seems to have adequate power after first starting, but after it warms up a bit, I think it's dropping cylinders. Power drops way down like it's only running on one cylinder. If I shut it down and let it sit, then restart, it has good power again, but only for a minute or so then the same thing happens again.

Any ideas what it might be? This is an oil injected engine and that system appears to be working fine. It's pumping water good.

Thanks for the help!
 
Top