If your motorcycle is blowing white or gray smoke at the redline but not at low speeds, and you suspect that gasoline is mixing with oil, it could indicate a problem with the fuel system or engine components. Here are a few potential causes to investigate:
Faulty Fuel Injector: A malfunctioning fuel injector can cause an incorrect fuel-to-air ratio, leading to incomplete combustion and the mixing of fuel and oil. Inspect the fuel injector for any clogs, leaks, or malfunctioning components. Cleaning or replacing the fuel injector may be necessary.
Carburetor Issues: If your motorcycle has a carburetor instead of a fuel injector, problems with the carburetor's float valve or needle may lead to excessive fuel entering the combustion chamber. This can result in the mixing of fuel and oil. Cleaning or adjusting the carburetor may help resolve the issue.
Worn Piston Rings: Worn or damaged piston rings can allow oil to pass into the combustion chamber, leading to oil consumption and the production of smoke. A compression test can help determine if there are any issues with the piston rings. If the rings are worn, they may need to be replaced.
Valve Seals: The valve seals prevent oil from entering the combustion chamber. If the valve seals are worn or damaged, oil can leak into the chamber, resulting in smoke. Inspect the valve seals and replace them if necessary.
Crankcase Breather System: The crankcase breather system helps regulate pressure within the engine. If it's clogged or malfunctioning, excessive pressure can build up, causing oil to be forced into the combustion chamber. Check the breather system for any obstructions or defects.
It's important to address this issue promptly to prevent further damage to the engine. If you're not experienced with motorcycle engine repairs, it's recommended to have a professional mechanic inspect and diagnose the problem accurately. They will be able to provide specific recommendations and carry out the necessary repairs to fix the issue.