clarkp Posted September 21, 2008 Report Share Posted September 21, 2008 I didn't notice any overheating at first - initial problem indication was burbling on the main jet - never happened before and the bike wouldn't run clean on the main jet. I tried the usual WFO to clean it out which never really worked and the bike began to get hotter and hotter. Hot enough to melt the plastic guard off of the muffler. I checked the radiator fluid which was full and then I pulled the two leads off of the thermostat and jumped them so that the fan ran all the time. Though, even with this the bike still ran hot and wouldn't run clean on the main. Is the problem an overheating issue that's causing the poor carburetion or is a plugged main jet causing the bike to overheat. Does anyone know if the inline thermo-couple is an actual thermostat that can block fluid flow through the radiator? If so, this may be the problem. I'm pulling the carb to see if the main jet is plugged and causing a lean conditiona which would make it run hot. Any other thoughts? Quote Link to comment Share on other sites More sharing options...
copemech Posted September 22, 2008 Report Share Posted September 22, 2008 Clark, A thermo switch is a switch. If the fan was working normally with it, it is fine. And it may not be the motor overheating if it is not puking coolant. May be just the exhaust overheating due to the 6 month old fuel and mudwasp nests! Clean it up real well before you bring it by. I hate working on dirty bikes! Quote Link to comment Share on other sites More sharing options...
clarkp Posted September 22, 2008 Author Report Share Posted September 22, 2008 OK, Copey, I understand from your post that the inline thermocouple is only a sensor that calls for the fan to run and does not block fluid flow - gotcha. I still can't figure out why it is running like horse-hockey on the main jet. The air filter is cleaner than Dick Cheney and the gas was mixed yesterday morning. It runs great on the pilot circuit and on the needle but when you call for main jet it sounds like its loaded up. Almost died a couple of times on the loop looking for some throttle and finding none. OBTW, it melted my fender, the little black muffler thingy, and some fuel line and an inline fuel filter. WTF? Quote Link to comment Share on other sites More sharing options...
copemech Posted September 22, 2008 Report Share Posted September 22, 2008 Clark, there is a possibility the main could be cloggeg, yet it would likely require almost an idiots repeated heavy running in a lean misfire condition while dumping way too much unburnt fuel into the exhaust,to try and clear a plugged jet to overheat the exhaust that badly! Does anything ring any bells here? Like continuously running down the road with it missing? And if you did all that trying to clear it, it the plug ok? Quote Link to comment Share on other sites More sharing options...
motofire Posted September 22, 2008 Report Share Posted September 22, 2008 Could a broken set of reeds have anything to do with this? Quote Link to comment Share on other sites More sharing options...
copemech Posted September 22, 2008 Report Share Posted September 22, 2008 Could a broken set of reeds have anything to do with this? Clark would be chuffed if he rode enough to actually break something, yet at this point I doubt it! We shall see! Quote Link to comment Share on other sites More sharing options...
john.b Posted September 22, 2008 Report Share Posted September 22, 2008 Just a thought, did you retarded the ignition just before this overheating started? Might have gone too far if you have. Quote Link to comment Share on other sites More sharing options...
turbodean Posted September 22, 2008 Report Share Posted September 22, 2008 Is the bike hard to start when warm??? I have the same problem with the exhaust getting very hot, melted the exhaust gaurd and rear mudguard and a brand new pair of Jitsie bottom's last time i rode it. Mine is also a nightmare to start when warm. Quote Link to comment Share on other sites More sharing options...
ham2 Posted September 22, 2008 Report Share Posted September 22, 2008 (edited) Hmm..this all sounds familiar..I'm all ears on this one------My steed Edited September 22, 2008 by HAM2 Quote Link to comment Share on other sites More sharing options...
jse Posted September 22, 2008 Report Share Posted September 22, 2008 I'm pulling the carb to see if the main jet is plugged and causing a lean conditiona which would make it run hot. Any other thoughts? Clark, In order to eliminate this as a possibility, I'd probably pull the headpipe off and check for carbon restriction (usually will be in the first 2-3" of the pipe and very rarely in the exhaust port, but it does happen) and then carefully inspect the whole system for any shift in the core that would cause an obstruction. Jon Quote Link to comment Share on other sites More sharing options...
clarkp Posted September 22, 2008 Author Report Share Posted September 22, 2008 ...would likely require almost an idiots repeated heavy running in a lean misfire condition while dumping way too much unburnt fuel into the exhaust,to try and clear a plugged jet to overheat the exhaust that badly!Does anything ring any bells here? Like continuously running down the road with it missing? And if you did all that trying to clear it, it the plug ok? Cope, you are a master diagnostician... yes, yes, I did all of the above while about a mile and a half from camp trying to limp the thing back to the truck. I suspected a plugged main jet, however, it seems unlikely since my Sherco has three lines of defense against that: the tank filter, an inline fuel filter (one melted), and the screen on the 'buretor. scudo - yes, the ignition is very slightly retarded and has been for over a year - this condition just presented itself so I'm less inclined to suspect timing. I pulled the carb and everything 'looked' clean - blew it all out with compressed air. Cope may be right again on the plug thang - two-strokes like two things: fresh gas and a new plug... The plug in it is about a year old, may have lost it's starch - I'll slip a new one in and check. Jon - I'll also pull the header pipe to see if it's all gummed up from two years of running on the 35 pilot. I'll also pull the reed cage to see if anything is fuzzy but Cope's right again; I ride the senior amateur class which means old AND slow. turboDean - no, I've never had any issue starting the bike when it's warm... she's a one-kicker in that condition. Quote Link to comment Share on other sites More sharing options...
clarkp Posted September 22, 2008 Author Report Share Posted September 22, 2008 Okay - I've found that the spark plug wire is partially worn through (exposing the conductor). Is it possible that at higher revs (what I took to be 'on the main jet') the abraded conductor created a condition where it wasn't able to deliver all the energy from the coil causing a weak spark / burbling that I was experiencing which lead to everything that Cope accused me of (and I did)... Quote Link to comment Share on other sites More sharing options...
copemech Posted September 23, 2008 Report Share Posted September 23, 2008 Okay - I've found that the spark plug wire is partially worn through (exposing the conductor). Is it possible that at higher revs (what I took to be 'on the main jet') the abraded conductor created a condition where it wasn't able to deliver all the energy from the coil causing a weak spark / burbling that I was experiencing which lead to everything that Cope accused me of (and I did)... Well Clark, this could be the case depending upon what it was rubbing upon. If it was rubbed by the plastic fan, I would not normally think it could find a suffuicient alternate electrical path to disrupt ignition, unless it was wet. This obviously needs to be corrected, as well as inspecting the cap connection. Try to correct these basic things and let me know, there is a possibility of a F/U box/ coil, or a stator or trigger coil problem. These issues do seem to pop up. Ckeck your coil ground wire as well for clean and tight. Might try removing kill switch in case of water entry. All basics to cover, we can always use mine for a tester if worse comes to worse. This is about the limit of my free advise over the internet, from here on out you must bring beer! And NO texting! Quote Link to comment Share on other sites More sharing options...
pete290 Posted April 24, 2011 Report Share Posted April 24, 2011 What did it turn out to be. My 2007 290 has started to do the same. ie the exhast shield has melted and the exhast system gets very hot. Everything else seems ok. Bike starts fine hot or cold. Quote Link to comment Share on other sites More sharing options...
copemech Posted April 25, 2011 Report Share Posted April 25, 2011 What did it turn out to be. My 2007 290 has started to do the same. ie the exhast shield has melted and the exhast system gets very hot. Everything else seems ok. Bike starts fine hot or cold. First thing most likely is same as in the "re pack " thread with excess oil accmulation and a hard run lighting it off. Second being timing set "too " slow for the bike and a lot of unburned fuel going downstream giving same result. Quote Link to comment Share on other sites More sharing options...
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