QuestionHey I have a 1974 Yamaha Dt250 with the Yamalube oil injection system. The
bike smokes way too much. It's a blueish color smoke, which makes me think
the 2 cycle oil is being injected to quickly. My uncle and I adjusted the oil pump
to the correct setting, and seems to be operating fine. I tried adjusting the fuel/
air mixture, but it didn't really help either. Any help you can give me will be
greatly appreciated. Thanks, Matt.
AnswerMatt,
-two things it might be, but most likely
the first:
-on the clutch side of your engine,
there is an oil seal on the crankshaft.
This seal can get hard or damaged over time and
the engine sucks your transmission oil in and burns it,
hence all the smoke you see.
-You may be able to change it from the outside
but have to remove the clutch and crankshaft
gear. It has to be carefully tapped in with
something the same size as the outside of the seal,
to avoid damage or getting it crooked.
-secondly, after running with so much oil smoke
the muffler can become oil logged.
This may clear up in time but can produce
smoke as it burns off. Sometimes they have
to be cut open and cleaned out if they keep
your bike from revving out at high speed.
-I think if you replace the crank seal your
problem will likely be fixed. Give it some time
after for the old oil to burn off.
Number 18 on this diagram:
http://houseofmotorcycles.bikebandit.com/partsbandit/oem_schematic_view~schem_de... %28Stock%29 Parts~dept_type_id~2~model_dept_year~1975~model_dept_mfr~Yamaha~model_dept_id~632141~model_dept_name~DT250B.asp
