[cyboy]

I have the 15hp Yamaha Enduro Long Shaft 2stroke. I took the boat out yesterday. The engine was acting up. Right when we got going after about 10min in the engine bogged. Didn't stop just lost most of the power while still at full throttle. Felt like fuel issues. So we took off the fuel filter and pumped fuel through it to flush any water or gunk. That flow was fine. Pretty much stopped the ocean maintenance check at that and returned to trolling since that was now top speed. Then the engine got better through the day. It would go normal and then bog for short periods then back to normal. No consistency. It would run best in the mid throttle range. Full throttle was bogging it just about all day. And when it would bogg I could get it back to normal by throttling way down and then slowly giving it more. Other than that it was running fine, pissing fine, and all was good. Any ideas? It seems like a fuel issue, but I was curious if i should look or worry about something else.

[Yamajoe]

You need to tear down your carbs and give it a good clean, pay special attention the main jet, and needle and pilot jet.