sam Posted October 14, 2010 Report Share Posted October 14, 2010 My friend lives 5 hours away, so I'm trying to diagnose his mechanical dilema via telephono! His 2006 290 Sherco is smoking and the smell is unpleasant, I imagine needs engine seals. I will have him check oil level, he has already tried running it down the road 5 miles to burn off muffler residue, still stinky, not premix smelling. Other symptom is bike is overheating after 30 min. of operation, Fan is working. Please refresh my memory, is overheating a thermostat issue or could it be the water pump seal, he will also check for milky oil. Could overheating be related to bad engine seals. Replys will be appreciated. Thank You. sam Quote Link to comment Share on other sites More sharing options...
joekarter Posted October 14, 2010 Report Share Posted October 14, 2010 Most of the time a bike with a bad crank seal on the wet side will have a BUNCH of glop coming out the exhaust (it'll look really rich). If the oil's not milky, it sounds like it may have a bad head gasket. Check to see if the coolant level is low, if it smells like premix, and if you have pressure at the radiator neck with the bike cold, the radiator cap off, and the bike running. Quote Link to comment Share on other sites More sharing options...
copemech Posted October 14, 2010 Report Share Posted October 14, 2010 Would agree with basics above. Ck fluids. Seems we have had issues of late re- the alcohol in the fuel deteriorating crank seals. If it is sucking in fluid from the gearbox side, they can actually form a vacume (or pressure) on the vent tube below the carb. Quick test might be to pull out the tube which runs down back of motor, clean the end and put to mouth to check for pressure changes. Sounds dumb, but works. Another method would be attatching clear hose an immersing in water to ck for suction or presure(bubbles). All point being, the pressures in the gearbox should not normally change much exept for temperature variations. Same with the cooling system. Quote Link to comment Share on other sites More sharing options...
neo Posted October 14, 2010 Report Share Posted October 14, 2010 (edited) I've had this on my bike when I made the main jet too lean (May be partially blocked in his case)... not sure why the the main jet would effect initial throttle use but it did in my case. Has he just got the bike or has he been playing with the carb? Best of luck. Neo Edited October 14, 2010 by Neo Quote Link to comment Share on other sites More sharing options...
copemech Posted October 15, 2010 Report Share Posted October 15, 2010 Another little thing that comes to mind. If the ignition is retarded too far, it leads to incomplete combustion and the the exhaust will overheat due to too much unburned fuel downsteram of the motor! Noticeable on a long hard run, maybe not so much off cold or putting around. Quote Link to comment Share on other sites More sharing options...
sam Posted October 16, 2010 Author Report Share Posted October 16, 2010 Update, My friend had enlightened me that prior to the bike running badly, he allowed an obnoxious dirttrack racer to ride his bike. The nincompoop immediately commenced to popping wheelies inwhich he looped out the machine. There after the bike began to run poorly. I suggested changing gear box oil, checking coolant and asked him to disassemble and clean the carb. Also, change his plug, he had not replaced the plug since purchasing the bike 4 years ago. Well, he says that the bike is back to running very good. I guess the moral of the story is do not allow happy, wheelie popping idiots to ride your bike. Thanks everyone for your input. sam Quote Link to comment Share on other sites More sharing options...
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