Question about 1986 Yamaha RD 350
Theres a few things that can be happening here...Im not sure if its spitting out fuel, oil, or coolant, so ill give u a quick explanation of all 3 possibilities.
first, there may be a blown crank seal. this ils the most likely of problems. im assuming that your engine still runs ok. but you have an excessive amount of blue-ish smoke and some oil coming out of the exhaust. this would require a very good technician to fix. the crankcases must be seperated to properly install a new seal.
second, you may have the same symptoms as stated above. but instead of the crank seal being bad, it may be the crankcases leaking oil. you see, theres no gasket between the crankcases. there is only a thin layer of a silicone-type gasket maker that yamaha uses to seal the cases. sometimes that thin gasket fails, and oil is allowed to leak into the crankcase, then is passed through the cylinder and exhaust. if you determine that it is oil burning, (youll know because of the very high amount of smoke compared to the left cylinder), split the cases and replace the crankseal, even if you think it may just be the gasket. they only cost about 8 dollars, and tahts cheap insurance.
third, it may be your head gasket leaking. unlikely, but a possibility. even though it would leak coolant into the exhaust, it can sometimes be mistaken for oil after it mixes with all of the carbon built up inside the pipes. youll know if its a bad head gasket if the bike is hard to start, and the coolant level in the radiator goes down after a short time riding. also you should notice that your engine bogs or sputters intermittently, but frequently.
finally, the last possibility is that your carburetor(s) arent adjusted properly. once you rule out the possibilities I listed above, then check make sure that your carbs arent overflowing. if they leak, then your getting too much fuel to your cylinders. if theres no leak on the carbs, then your jetting is just a little bit too rich. reducing the main jet by 1 or 2 sizes should help this problem. a good indicator of a rich condition is having to frequently change the spark plugs just for the bike to run properly.
hope this helps you out at least a little. if you have any questions or want anything clarified, feel more then free to contact me.
Posted on Jul 28, 2009
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Posted on Jan 02, 2017
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