tpmadhare Posted February 8, 2014 Report Share Posted February 8, 2014 Hi there really need some help I just brought a 2010 sherco st 3.0 works replica when I went to view it last weekend seemed to be fine run OK rode OK etc got it home put it away all week got it out to ride today fired up ran OK for 10 min then started to die on lower rpm til it cut out found out it was flooding took carb apart found floats where sticking cleaned refitted seem OK led it ticking over for ten min then went to ride it pulled away and bang big backfire flames out the exhuast now won't start got spark got fuel got good comprestion 150 psi on tester all it dose is back fire with flames wont start any ideas please Quote Link to comment Share on other sites More sharing options...
lestergg2005 Posted February 8, 2014 Report Share Posted February 8, 2014 Try checking the woodruff key that correctly locates the flywheel. If this has sheared it would cause the banging that you describe when trying to kick the bike over as the timing will have slipped. Worth a check !! Quote Link to comment Share on other sites More sharing options...
tltel Posted February 8, 2014 Report Share Posted February 8, 2014 Big bang, Probably sheered the woodruff key on flywheel. If it went bang because of too much fuel it can make the engine fire backwards while the flywheel momentum is going forwards and the key gets sheered. TLTEL Quote Link to comment Share on other sites More sharing options...
copemech Posted February 9, 2014 Report Share Posted February 9, 2014 Change the sparkie first, just in case. Then proceed with the other. Quote Link to comment Share on other sites More sharing options...
tpmadhare Posted February 9, 2014 Author Report Share Posted February 9, 2014 Thanks every one I will be making a tool to remove flywheel at work tommrow so I'll know more then Quote Link to comment Share on other sites More sharing options...
midlife Posted February 9, 2014 Report Share Posted February 9, 2014 Had sherco 250 2011 done same thing. Stator Quote Link to comment Share on other sites More sharing options...
neo Posted February 10, 2014 Report Share Posted February 10, 2014 Gotta be the woodruff key ... can't see how it could be the stator? Maybe that stator nut was a bit loose?? Best of balance. Neo Quote Link to comment Share on other sites More sharing options...
petenete Posted February 10, 2014 Report Share Posted February 10, 2014 mine did this it was the stator when you kicked it back fired Quote Link to comment Share on other sites More sharing options...
tpmadhare Posted February 10, 2014 Author Report Share Posted February 10, 2014 Took fly wheel off and half the wood ruff key was in it the other half still in the shaft so if order 2 new ones should be here wensday so fingers crossed Quote Link to comment Share on other sites More sharing options...
tony27 Posted February 10, 2014 Report Share Posted February 10, 2014 Make sure there is no damage to either taper, if there is then a you'll need to remove it so the tapers lock together properly. A bit of fine wet & dry will work for the crank, using some fine lapping compound between the 2 parts in a twisting motion will match them up, don't go mad on it though as the flywheel will move inwards on the crank if you overdo it Quote Link to comment Share on other sites More sharing options...
dadof2 Posted February 11, 2014 Report Share Posted February 11, 2014 Either a duff HT coil or duff stator can cause these kickbacks. As soon as you get the engine running check the timing advances and retards correctly using a strobe light and marks on the flywheel. Quote Link to comment Share on other sites More sharing options...
thats_a_five Posted February 12, 2014 Report Share Posted February 12, 2014 If the flywheel nut was not properly tightened, the flywheel will move slightly on the shaft and eventually shear the woodruff key. When that happens, the timing goes way out and often results in a storing kick back or simply not starting. Usually simply , clean up the shaft and bore if they are scored, replace the key and you are back riding. Quote Link to comment Share on other sites More sharing options...
tltel Posted February 12, 2014 Report Share Posted February 12, 2014 I would say probably just a loose nut that caused it to shear. Something to keep a check on. Good luck with the bike. TLTEL Quote Link to comment Share on other sites More sharing options...
tpmadhare Posted February 18, 2014 Author Report Share Posted February 18, 2014 Hi all thanks for all the help it was just the woodruff key its all fixed and running spot on thanks to every one Quote Link to comment Share on other sites More sharing options...
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