pillns Posted March 12, 2007 Report Share Posted March 12, 2007 Hi Im pretty much a newbie so all help would be much appreciated. Ive purchased a 2002 Sherco 290, got it fairly cheaply. Stupidly i didnt go to see the bike as i bought it from ebay and sent a friend with a van to pick it up. Two problems - firstly the engine has a knocking/tapping noise which increases with revs, it is fairly loud but the bike dosent seem to be down on power or smoke more than it should. any suggestions? Also when i rev the bike, either in neutral or in gear, when i let off the throttle the revs seem to stay up for a short while then eventually drop back down to tickover? Really not sure what to try so any suggestions would be great! Many thanks Quote Link to comment Share on other sites More sharing options...
scoobie Posted March 12, 2007 Report Share Posted March 12, 2007 Hi, Depends on the noise, hard to diagnose without hearing it. You may be lucky and it could just be piston slap, or it's running to 'lean' - what's the mixture and what does the plug look like? Then again it could be the small end. If your really unlucky - which is usually my case - then it could be the main bearings. Regarding the revs, the throttle slide may be sticking inside the carb, or the actual throttle body on the handlebar may be sticking, or even a kink/catch in the cable somewhere. Start with the easy stuff and check the throttle at the bar, lube and check the routing of the cable, then check the throttle slide itself - the spring could be knackered. Also check there isn't any air leaks on both carb manifolds while your at it. If that doesn't work come back to us and it maybe time to take-off the carb to strip and clean it and blow-out the jets. Hope it hepls. Quote Link to comment Share on other sites More sharing options...
pillns Posted March 13, 2007 Author Report Share Posted March 13, 2007 Thanks scoobie, the plug is brand new - no colouring, and im running it at 75:1. If it is piston slap/small end then how should i go about rectifying the problem? Any decent sherco dealers about? It sounds to me like more of a tapping noise coming from the top of the engine rather than lower down. As for the revs, ill try what youve mentioned. Ive noticed thhat there is a clear pipe running from one side of the carb to the other with a slit cut out of the bottom - is this a breather or should it be intact? Also there is a small adjuster screw on the left of the idle control screw - what does this adjust? Sorry if im asking simple questions! Quote Link to comment Share on other sites More sharing options...
mick Posted March 13, 2007 Report Share Posted March 13, 2007 Does it stop when you pull the clutch in? Mine (a bit older than yours) the clutch plates rattle with the clutch out but it's nice and quiet with it in Just a thought Mick Quote Link to comment Share on other sites More sharing options...
pillns Posted March 13, 2007 Author Report Share Posted March 13, 2007 Its still there whether the clutch is in or out. Ive just pulled the plug out - it is brand new (so i was told) but it had a coffee sort of colouring on it and it was dry. Its a champion N2C. Is that right? Quote Link to comment Share on other sites More sharing options...
gasgasssser Posted March 13, 2007 Report Share Posted March 13, 2007 (edited) Should be an NGK BP5ES,Coffe coulor is normal. Edited March 13, 2007 by gasgasssser Quote Link to comment Share on other sites More sharing options...
copemech Posted March 14, 2007 Report Share Posted March 14, 2007 Find someone with experience near you. Do you belong to a club? The small screw is the MIX, it controls low speed performance and idle quality! Some sounds are normal, others not! Quote Link to comment Share on other sites More sharing options...
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