How do I Make a Four Wheeler Quit Smoking?

Perform a comparison check first to find the base compression. You can use a compression checker similar to the kind used for outboard motors, if you have one.

Add some 30 weight oil into the sparkplug hole. Use high grade oil and avoid cheap products.

Re-check the compression. If the compression increases after you have added the oil, the problem is the rings. If the compression remains the same, you have a problem with the valves.

Wrench open the oil tank plug. You may need to jack the vehicle up to reach the tank. Drain out the existing oil using a pan and funnel and see if it is gritty or gray in color and then replace it completely in the system. If the gray color comes back after an oil change, try running a small quantity of kerosene through the system to clean it out. Only run the kerosene for 15 seconds with the engine switched on, then drain it all out again and re-fill with ordinary 30 weight oil.

Unscrew the oil filter cap and take out the oil filter on top of the valve cover as this can, over time, become dirty, degraded and unworkable. It will be full of oil, so take care when removing it. Oil filters help cool the engine by transferring heat away from it, as reported by Synlube.

Continue draining and re-filling the oil in the system until the oil comes out looking clear and normal. This may take up to six oil changes. If smoking is still happening after this, there are other checks and repairs you can do, including rebuilding the carburetor.

Rebuild the carburetor, or pay for an experienced mechanic to do so for you. According to Four Wheeler, the carburetor can be the source of problems such as emission of black smoke.

Replace the valve seals if the smoke gets worse when the engine is hot and on start-up, the cylinder head and the cam belt. This should eliminate blue smoke and any unwanted noises related to the smoking issue, such as knocking.