Screech, a puff of smoke, then oil/fuel from exhaust

[Chillee B]

Hi guys,
I just recently purchased a 1988 50HP Yamaha 2 stroke outboard off of ebay locally. When the outboard starts, it will give a couple of short screeches as it warms up, then appears to idle fine. When you start to give it a little gas and let the rpms start to climb, you'll get some hesitation, a short 'screech', a puff of smoke from the exhaust from the front of the motor (at about where the hinge/bracket is) then a small splash of oil/fuel mixture from the same area.

Any ideas? Would the reed valves make a short 'screech' sound?

The gentleman I bought it from said he had cleaned the carbs the day before.

I plan on pulling the plugs in the next few days to check them.

Any suggestions or advice is greatly appreciated. I like to think I am mechanically inclined, but this is my first experience with 2 strokes.

Thanks in advance for taking it easy on a newbie.

 

[studlymandingo]

Re: Screech, a puff of smoke, then oil/fuel from exhaust

Check compression on all cylinders. Sounds like there could be some issue with ignition timing.​

 

[Ray Neudecker]

Re: Screech, a puff of smoke, then oil/fuel from exhaust

Common cause is the top seal leaking.

 

[Chillee B]

Re: Screech, a puff of smoke, then oil/fuel from exhaust

Man, am I embarrassed. :redface:

Thanks for all the suggestions guys, but it was all user error.

I have the motor on a stand. I would start it and then adjust the throttle by moving the linkage on the carbs. (Just like you would on a car.) I was not adjusting the throttle by moving the linkage that the throttle cables attach to. Doh! The throttle cable linkage is attached not only to the carbs, but what I am guessing is a mechanical timing advance. Right?

Anyhow, it ran fine after I figured that out.

Thanks again.

 

[Ray Neudecker]

Re: Screech, a puff of smoke, then oil/fuel from exhaust

Yes that is the mechanical timing advance. Glad it is working for you.