1988 Yamaha 350 warrior has a smoking issue?

A smoking issue in a 1988 Yamaha 350 Warrior can have several potential causes. Here are a few things to check:

1. Engine Oil Level: Ensure that the engine oil level is correct. If the oil level is too high, it can cause smoking and oil burning. Check the oil level with the dipstick and add more oil if necessary.

2. Piston Rings: Worn piston rings can allow oil to enter the combustion chamber and cause smoking. If the piston rings are worn, they will need to be replaced.

3. Valve Seals: Worn or damaged valve seals can also allow oil to enter the combustion chamber. If the valve seals are faulty, they will need to be replaced.

4. Oil Pressure: Low oil pressure can cause the engine to smoke. Check the oil pressure with an oil pressure gauge to ensure it is within the specified range. If the oil pressure is low, it could indicate a problem with the oil pump or other engine components.

5. Air Filter: A dirty or clogged air filter can restrict airflow to the engine, causing the fuel mixture to be too rich and resulting in smoking. Clean or replace the air filter as needed.

6. Exhaust System: Check for any leaks or blockages in the exhaust system. An obstructed exhaust can cause smoking due to incomplete combustion.

7. Engine Coolant: Ensure that the engine coolant level is correct. Low coolant levels can lead to overheating and smoking. Check the coolant level in the radiator and refill if necessary.

8. Spark Plugs: Check the condition of the spark plugs. Worn or fouled spark plugs can cause incomplete combustion and smoking. Clean or replace the spark plugs if needed.

If you are unable to identify and fix the smoking issue yourself, it is best to take the vehicle to a qualified mechanic or a Yamaha authorized service center for diagnosis and repair.