Carbon problem Sears outboard

[Carbonizer]

I am having carbon buil-up problem with my sears 1.2HP outboard Model # 369-58230(circa early 60's). After running for about 30 minutes, the spark plug gums up and I have to either replace it or clean it. No easy feat while fishing in a canoe. Here is what I have done so far: I de-carbonized completely the muffler compartment. Also brought it to a small engine mechanic who changed the condenser and had the points checked(they are fine). He also suggested I go to a hotter burning plug, which I did, went from a Champion CJ8 to a CJ6. Gas mixture is recommended at 25:1 in the manual, I am now up to 50:1 and still the problem persists. Any suggestions on rectifying this problem would be greatly appreciated, thanks.

 

[Capt Ron]

Re: Carbon problem Sears outboard

Did the mechanic perform a compression check? Low compression will result in incomplete burning of the fuel mixture and oil deposits.

CaptRon

 

[CATransplant]

Re: Carbon problem Sears outboard

The CJ8 is a hotter plug than the CJ6, so you went the wrong way. If your plugs are fouling, try gapping them to .035. If that still doesn't work, try using a synthetic oil. That could help.

I believe that is a Tanaka-built outboard. Be sure to use oil designed for chainsaws in your fuel mix. I do not know the proper ratio for that model. If there's a tag on the engine, follow that.

I just checked on that engine at www.searspartsdirect.com. It calls for a J17LM spark plug. Try that. You can see a parts blowup for your engine at that site. Just enter your model number. Some parts are available through that site.

 

[steelespike]

Re: Carbon problem Sears outboard

Its not wrong to try the chainsaw oil but my aftermarket manual says TCW oil my TCW3 oil container recommends use in all sorts of 2 stroke motors from string trimmers to outboards.Ratio is 50:1.Air gap between the coil armature legs and flywheel is .013.You can set it with something like a file card or manilla folder.Point gap is .013.(Not the .020 of 99% of motors).points should just open as M mark on flywheel
lines up with the match mark on crankcase.On carb the jet needle position in throttle slide is set with a clip. Clip should be in the 3rd notch from the top.
Does the motor seem to shudder (4 stroke)dug dug dug when throttle is first opened and perhaps smooth out to a more excited buzz.Or does it tick right off.with an eager buzz.
If it ticks right off smoothly most likely the needle is right.