stilly Posted January 19, 2011 Report Share Posted January 19, 2011 Can any 1 help my sherco has got me head battered, a few weeks ago it kicked back on me and the rear wheel rotated clockwise, I stripped it timeing set to standard, new woodruff key put it back together, got the nut as tight as it would go with a scaffy bar on the end, 2 meters out the shed it started spluttering and the wheel rotated backwards again, 3 times I have done this in the process I have snapped my kickstart an will have it to replace now, help 1, why dose the wheel rotate backwards, 2, could the groove in the flywheel be worn and that's the problem, 3, is there a bigger woodruff key I can put in, any ideas much appreciated Quote Link to comment Share on other sites More sharing options...
garyc Posted January 19, 2011 Report Share Posted January 19, 2011 I've seen this happen before, but not recently. When the bike splutters the engine stops briefly before the piston has reached the top, the ignited gas then pushes the piston back the other way. In 2 strokes there is no reason why the engine can't run in reverse, but it tends to stay running forward because that's how it was started and the flywheel keeps it going. So any 2 stroke that splutters significantly can run backwards, but what really makes this more likely to happen is over-advanced ignition timing. This means the spark plug is sparking too early and before the piston is at the top. (the factory settings are usually a little bit of spark advance though because this helps make more power). Over-advanced ignition timing will cause knock and splutter, which causes the engine to slow down and then the over-advanced spark helps push the piston back down before it reaches the top. So check your timing. I don't mean check that it's at the factory settings, sometimes they make mistakes. Measure it as per these instructions found here: http://www.sherco.com/wayne_corner.html If the timing looks right, it might be that it's just the splutter, so clean your carb and change your spark plug. If that doesn't work it might be your electrics, in which case see if you can find a mate with the same bike who's willing to let you swap bits over to see if you can diagnose which bit of the electrics has gone faulty. Quote Link to comment Share on other sites More sharing options...
t-shock 250 Posted January 19, 2011 Report Share Posted January 19, 2011 What year sherco is it? Older ones suffer from ignition stator failure which, in the early stages can result in odd variable timing behaviour. Quote Link to comment Share on other sites More sharing options...
stilly Posted January 19, 2011 Author Report Share Posted January 19, 2011 Sherco is 2.50 2004 if I remove the flywheel put a new wood ruff key in it only seems to last a short while then it kicks back and splutters, when it's running it's sweet as a nut no spluttering, the first time it did it the fly wheel must have slipped on the key, as described on here it took loads of try's to pull the flywheel off and then it came of, put it back together and it lasted a few hours, don't understand why it was running ok and now all I have done is put a new key in, do I need to do the timeing with a strobe light Quote Link to comment Share on other sites More sharing options...
chewy Posted January 19, 2011 Report Share Posted January 19, 2011 Remember that the key is only there to position/time the flywheel to the crankshaft. It is the Taper that does the work, is it damaged, you can check it by applying engineers blue or even a bit of marker pen (put it on one surface leave the key out offer the other part up and rotate it .. remove second part and look for "witness marks; where the ink has been removed), in an ideal situation you want all of it evenly rubbed off. I have had to lap these tapers before after damage/bruising due to key shears and resulting "chew up" , it is a job for someone with experience really but to check the taper is mating isn't going to do any harm. worth checking ! Quote Link to comment Share on other sites More sharing options...
meggy Posted January 19, 2011 Report Share Posted January 19, 2011 Had this on a sherco 125 kept braeking keys had to lap the flywheel to the shaft using fine laping paste not a long job and insant cure Quote Link to comment Share on other sites More sharing options...
copemech Posted January 20, 2011 Report Share Posted January 20, 2011 Does sound as though your taper fitment on the shaft and flywheel may need attention. These things will not shear a woodruff key if the flywheel is fitted properly, reguardless of other ignition problems. Not quite sure about "got the nut as tight as it would go with a scaffy bar on the end" really equates to, but to torque this properly, you need a flywheel holder and torque wrench set to 100nm. Exceeding this could damage the threads, then you are screwed, so you cannot simply drive it into submission with a rattle gun. Quote Link to comment Share on other sites More sharing options...
jam Posted January 20, 2011 Report Share Posted January 20, 2011 My mate Ed had the same problem with his 290, he said;- when it cools/cold runs ok but as it warms up the bike quickly splutters and ran backwards....its the stator breaking down when it warms up....just need to replace and will be fine..... Eddie Hope this helps Quote Link to comment Share on other sites More sharing options...
stilly Posted January 20, 2011 Author Report Share Posted January 20, 2011 I have put it back together set timeing to standard setting, put thread lock on the woodruff key and shaft and threads, everything tightened back up to 75 ft lbs, it started ok ran for few minutes and then started spluttering, I am going to strip all the wires out and clean them and clean the carb just in case it's dampness or something else i might have missed before I buy a stator will keep you all informed thanks for the info but still I have to batter my head on the wall when will I get to ride again, Quote Link to comment Share on other sites More sharing options...
t-shock 250 Posted January 20, 2011 Report Share Posted January 20, 2011 I'd bet my lunch that its the stator, given that it seems to be ok until it warms up. Just like mine did. Quote Link to comment Share on other sites More sharing options...
tony27 Posted January 21, 2011 Report Share Posted January 21, 2011 Bite the bullet & order a stator from Chris at Splatshop, sorted my ignition problem a year or so ago. Didn't end up having to fit it as it scared the other 1 into behaving Quote Link to comment Share on other sites More sharing options...
stilly Posted January 21, 2011 Author Report Share Posted January 21, 2011 Mmmmmmmm what is going on now I have stripped the carb down cleaned it like a new pin, stripped all the wiring out I did find some dampness on some wires, got a new kickstart,(expensive) it has started up and ran for half a hour that's all the time I had to play it's dark, it ticks over great aswell, could I have been looking and blaming the stator and it was dampness all the time, dont believe it, Sunday will tell because I will be out all day fingers crossed, I will inform on Monday if it's sorted cheers every 1 for the info. Quote Link to comment Share on other sites More sharing options...
ham2 Posted January 21, 2011 Report Share Posted January 21, 2011 ...... Didn't end up having to fit it as it scared the other 1 into behaving Ha,my mate insists on RAC membership for the very same reason..his cars have never broken-down when he has valid membership..kharma insurance Quote Link to comment Share on other sites More sharing options...
b40rt Posted January 21, 2011 Report Share Posted January 21, 2011 ..kharma insurance Didn't work for Boy George. Quote Link to comment Share on other sites More sharing options...
toofasttim Posted January 22, 2011 Report Share Posted January 22, 2011 Had this on a sherco 125 kept braeking keys had to lap the flywheel to the shaft using fine laping paste not a long job and insant cure I remember having to do this on Sherpas. Quote Link to comment Share on other sites More sharing options...
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