luke88 Posted November 28, 2012 Report Share Posted November 28, 2012 hi, just bought a 2005 sherco 290, recently had an oil change, i got the bike home put fresh fuel in and it started straight away with choke, if i turn off the choke it stalls after about 20 seconds but would start atraight away again with choke, it then cut out after running for about 20 mins in total and wont go again, there was oil coming out of the breather pipe at the top of the engine and the spark plug had a lot of oil in it, any suggestions to whats causing this?// thanks Quote Link to comment Share on other sites More sharing options...
hiside Posted November 28, 2012 Report Share Posted November 28, 2012 Hi, I am definitely not a mechanic, and there are a lot of guys here that have forgotten more than I will every know, but I have had a similar problems on a few of my bikes after just purchasing them used. Including a 2003 Sherco 2.9. The choke bypasses the main jet. If the main jet is clogged, from sitting for long periods of time, especailly without fuel stabilizer in it, the bike will run fine with the choke on, but when you shut the choke off the fuel can't get through anymore. You can remove the carb, remove the float bowl from the bottom of the carb, and there are some brass fittings you will see on the inside of the carb with small pin holes in them. These are the jets, They can unscrewed and removed from the carb assembly. I simply remove them, get some carb cleaner, and soak the jets in the carb cleaner for a few minutes then blow them out with compressed air, then reassemble. Somethimes before you clean them, if you hold the jets up to the light and look through the small hole, you will see it is out-of-round from the gunk inside. Hopefully that helps. Quote Link to comment Share on other sites More sharing options...
luke88 Posted November 28, 2012 Author Report Share Posted November 28, 2012 i will give it a go! i guess the oil on the spark plug will just be from running with the choke on all the time! it hasnt been used for the last 12 month so makes sense it could be blocked up! thanks for the help! Quote Link to comment Share on other sites More sharing options...
dombush Posted November 28, 2012 Report Share Posted November 28, 2012 Hi There can be a number of causes for the symptoms you describe. However, lets start with the most likely. Be careful with the plug looking oily after 20 mins running with the choke on, this is a reasonable situation given that the choke would cause excessively rich running after 1-2 minutes. The previous post dealt with the potential for a blocked jet. This is entirely feasible but just one of a number of causes. For oil to be pushed out of the gearbox breather this means that the gearbox is being pressurised from the crankcase. The most likely reason for this is a damaged crank seal on the clutch side.To check this is the cause, get a glass of water and with the engine running, submerge the breather tube into the water. If the tube either blows out a continuous stream of air or starts sucking up fluid then its likely that the crankcase seal has failed. A very slow bubbling ( a few bubbles in a minute) could just be air expansion due to warming of the gearbox. This is not necessarily a problem This seal can be replaced without removing the engine, but does require some knowledge and tools to do so.Remove the kickstart and Rear brake pedal Drain coolant and remove the water pump housing Drain the gearbox oil. Remove the clutch cover (preserving the gasket) remove the clutch pressure plate and plates Hold the clutch basket with a special tool to allow the crank pinion nut to be loosened. Hold the clutch hub with a special tool to allow the clutch hub nut to be loosened. Remove the clutch components then remove the crank pinion and woodruff key The seal can then be removed with a sharp hook or other tool that wont gouge the aluminium crankcase or the main bearing that sits behind the seal. The new seal can then be fitted.carefully after greasing the lip-seals and the taper on the crank. Care must be taken to ensure the seal is inserted perfectly square and flush . Of course, if the breather doesnt bubble, and it isnt a blocked jet either.... we'll think some more. Dom Quote Link to comment Share on other sites More sharing options...
goudrons Posted November 28, 2012 Report Share Posted November 28, 2012 Pilot jet blocked? The bike is meant to idle/run slowly on the pilot jet. If it's blocked it'll start and run on choke but the minute it's turn off it'll die unless it's rev'd up high enough to run on the main jet. Old fuel is a likely cause and fuel goes off within a few weeks these days. Take the carb off and clean it out, remove and check the little jets and blow them out with some carb cleaner/air (so you can see daylight through them) The pilot is usually a little slot headed screw up inside the float bowl with a tiny hole in it. Check the fuel in the tank isn't contaminated, it's also worth fitting a little inline fuel filter. If you are going to store your bike more than two weeks, turn the fuel off and drain the fuel out of the float bowl. Most carbs like the dellorto have a nut under the float bowl to drain off the fuel. (don't turn the fuel off and run the bike dry, you'll end up overheating it) Quote Link to comment Share on other sites More sharing options...
luke88 Posted November 29, 2012 Author Report Share Posted November 29, 2012 Many thanks for the advice i am going to try cleaning out the carb tomorrow and go from there! Could the oil from the breather pipe just be because it has had a recent oil change and this was the first time it has been run since? maybe they put too much oil in or it gets displaced once things started moving again?? thanks Quote Link to comment Share on other sites More sharing options...
copemech Posted November 30, 2012 Report Share Posted November 30, 2012 Many thanks for the advice i am going to try cleaning out the carb tomorrow and go from there! Could the oil from the breather pipe just be because it has had a recent oil change and this was the first time it has been run since? maybe they put too much oil in or it gets displaced once things started moving again?? thanks When the oil is changed, normally the bike is laid over to the left side, which does tend to slosh things that way in the vent chanell, so it could be temporary I suppose. Excess oil may vent out as well. Vent hose should run up over the carb, between the fuel line and carb body, then down to skidplate. That keeps water out and oil running back in with normal expansion. Quote Link to comment Share on other sites More sharing options...
luke88 Posted November 30, 2012 Author Report Share Posted November 30, 2012 hi took the carb off today, cleaned all the jets, it will now start up without choke and run better but when its rev'd up its like its running really fast and takes a while for the revs to come back down and settle again, still wont tick over without choke but a lot better than it was, tried adjusting the mixtures but no matter what the revs wont respond fast and then takes ages for them to come back down again? any ideas?? thanks, Quote Link to comment Share on other sites More sharing options...
copemech Posted December 4, 2012 Report Share Posted December 4, 2012 (edited) hi took the carb off today, cleaned all the jets, it will now start up without choke and run better but when its rev'd up its like its running really fast and takes a while for the revs to come back down and settle again, still wont tick over without choke but a lot better than it was, tried adjusting the mixtures but no matter what the revs wont respond fast and then takes ages for them to come back down again? any ideas?? thanks, May not be totally clean on the pilot if it was junked up! One fellow just replaced his, as he could not clean it totally! Collect what comes out of the bowl when you break it over a clear glass or plastic container to see what comes out. Fuel may be contaminated with water or other stuff. Be critical! Edited December 4, 2012 by copemech Quote Link to comment Share on other sites More sharing options...
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