smoky 2 stroke

[nem_bee]

I've been working on a 1997 j6 johnson 6hp and finally have it running well.

It however still smokes quite a bit.

I have rebuilt carb and set idle screw to specs. I have new 91 octane ethanol free gas and ive tried it with 50-1 and 75-1 mix (per leroys ramblings tried 75-1) with full synthetic 2-stroke oil and originally was using 50-1 semi synthetic quicksilver brand. The new fuel and full synthetic didnt seem to change things.

Its running in a barrel. Runs fine and smokes a little at idle but if reved up it puts a 10x10 cloud of white grey smoke up.

It continues smoking at any throttle level, and is not overheating.
I did a decarbon procedure and then put in brand new ngk plugs and no change.

Before and after installing new plugs, i have tried pulling plugs and both plugs are wet with fuel and no water droplets. Compression is even between cylinders and both cylinders look the same inside from plug hole (not visibly spotless/clean, normal amount of black color).

Its not cold out now and ive let it warm up for half an hour and no change..

I am thinking despite these observations I may still have a blown head gasket but looking for any advice or anything else to check before ordering head gasket...

I know Ive some 2 strokes in the past that didnt smoke nearly this much. But am I just being overly picky/is it possible this is normal?

 

[thumbnut]

If it were mine...I'd put her on a boat and run her a bit before anything else. If you can determine if smoke is steam or exhaust that would help...

 

[oldboat1]

You do have a slow/idle speed needle valve that you could try to adjust a little leaner (clockwise). I would use the 50:1 mix. If in a barrel, get the water about half way up the leg, and don't rev it -- good idea to keep the hose running while testing. As thumbnut says, on the boat is best. I prefer the oem Champion plugs gapped at .030, but your call.

 

[boobie]

What's the temp ?? Is it getting warm enough ??

 

[ondarvr]

If you're slow it takes about 10 minutes to check the head gasket. A grey/white cloud that size sort of indicates something more than just normal 2 stroke smoke.

You didn't stay what the compression was.

The 91 octane fuel is a waste of money, there's no reason to use it in this motor, just use 87.

I have three of these motors, only slightly older, none smoke much.

 

[gm280]

Sure sounds like you are burning fuel AND water. I believe you either have a head gasket issue or a block issue. Hope for the head gasket. JMHO

 

[oldboat1]

^^good points. Running without a thermostat installed? Did the motor overheat at some point? (not sure if this is your motor, or working on someone else's).

You were having some prior issues -- maybe an exhaust blockage that hasn't been fully cleared yet. I had that on one or two. (A lot of exhaust build up in the leg and smoking, and had problems getting them to run smoothly.)

 

[82rude]

Running in a barrel will produce more smoke than on a lake.Just like running in a barrel will make that water very dirty.

 

[F_R]

You say you did a decarb. That certainly will make it smoke like crazy till it burns all that crud out of the exhaust system. Get it out of that barrel and onto a boat on the lake and run it hard for awhile. THEN see if you still have anything to worry about.