yahmaha 90 won't rev, idles fine???

[smokey-magnum90]

Ok, so I just bought smoker craft magnum with a 1990 yahmaha 90 hp 2 stroke on the back. It had been sitting for about 3 years and it ran fine when I got it. Yesterday I was cruising at about full throttle and it went from about 45 mph to about 30. And it is idling fine, but it won't go over about 15 mph? The plugs were wet when I pulled them, so I don't think its starving. Could it be a diaphram? Please help.

 

[JB]

Re: yahmaha 90 won't rev, idles fine???

You probably dropped a cylinder, smokey. That engine idles fine on 2.

My guess is you have a gummed carb, but you need to ID which cylinder is dead, then troubleshoot.

 

[smokey-magnum90]

Re: yahmaha 90 won't rev, idles fine???

I don't think I dropped a cylinder because after fiddling around with the primer bulb and the plug caps it ran fine for a few minutes. But when I slowed down to an idle it idled fine for a few minutes, Then went to rev it back up and it was running crappy again. Oh btw, running at WOT isn't a big deal on my motor because it has a speed prop, so it maxes out at about 47 mph at 4500 rpm (redline is 5500).

 

[bowhuntrrl]

Re: yahmaha 90 won't rev, idles fine???

Oh btw, running at WOT isn't a big deal on my motor because it has a speed prop, so it maxes out at about 47 mph at 4500 rpm (redline is 5500).

You need to run a prop with less pitch and not your "so called" speed prop !!! It is harmful to the engine to run at full load at less than the WOT rpm staed by the manufacturer. The engine is working too hard trying to pull that pitch. Put on a prop that will allow you to get 5400-5500 rpm, you will probably even go faster !!!

 

[JUSTINTIME]

Re: yahmaha 90 won't rev, idles fine???

sounds like carbs