Yamaha 2004 with new SBT engine, fouling plugs

[mstraight]

Installed new SBT engine this past winter(Michigan). Started running with no issue. The more we run it, the more I need to replaced the fouled plugs. One set each weekend, if not more. The previous owner had carb work done and when the carbs were reinstalled there was no gasket on the manifold. I found it in the bottom of the ski when I pulled old engine. When I reinstalled the carbs, I properly installed the gasket. Could the carbs need tuning because of this? What would cause such a fouling of the plugs at this rate? The ski will either not start or only go 20MPH, when plugs need replacing. I cannot get Yamaha oil at my local dealers, I am using Kawasaki TC-W3. Thoughts on if Oil or carbs are my problem?

[mstraight]

Re: Yamaha 2004 with new SBT engine, fouling plugs

It is an Yamaha 800 XLT - sorry for the omission

[SBT-Tech 1]

Re: Yamaha 2004 with new SBT engine, fouling plugs

Sounds like carb issue. Kawasaki oil should be fine.

[mstraight]

Re: Yamaha 2004 with new SBT engine, fouling plugs

Any chance you can provide more color? The carbs were not touched / adjusted between the old engine and the new SBT engine. What direction could you point me?

[SBT-Tech 1]

Re: Yamaha 2004 with new SBT engine, fouling plugs

Was the engine running okay previously?
You replaced the engine, what had happened to it?
Carburetors should be looked at to see if they are clean and adjusted correctly.
Pop off pressure is 45-55 PSI.
Low screws are 1 7/8 turns out.
High screws are 1/2 turn out.

[mstraight]

Re: Yamaha 2004 with new SBT engine, fouling plugs

Was the engine running okay previously?
You replaced the engine, what had happened to it?
Carburetors should be looked at to see if they are clean and adjusted correctly.
Pop off pressure is 45-55 PSI.
Low screws are 1 7/8 turns out.
High screws are 1/2 turn out.

Engine ran and then the "engine was toast" Piston came apart. New one runs great with new plugs but fouls too quickly.

[SBT-Tech 1]

Re: Yamaha 2004 with new SBT engine, fouling plugs

If a piston came apart then there was a burning issue. Either an air leak or carburetor problem. Have the carbs rebuilt by someone that really knows that engine. It is critical to get the carbs correct on the yamaha power valve engines. We see warranty engines come back all the time that have lean burn issues that destroy the pistons.

[mstraight]

Re: Yamaha 2004 with new SBT engine, fouling plugs

Contacted local Yamaha dealer and they do not want the job. Does anyone have a lead for Southwest Michigan carb tuner?