tjp Posted May 13, 2010 Report Share Posted May 13, 2010 Hi Guys, I have an 08 250 sherco which I love. It starts easily, idles great, it pulls smoothly from low revs through into a nice usable mid range and then it all goes wrong!. The bike absolutely refuses to rev out, its as though it hits a rev limiter!. I have made sure jetting and fuel/oil ratios are correct, fitted a new plug and ensured all electrical connections are clean and tight. Has anyone got any ideas as to what I can try next?, I feel its going to be an electrical issue but was hoping it isn't the stator! Thanks in advance for any advice/ideas Quote Link to comment Share on other sites More sharing options...
mcman56 Posted May 13, 2010 Report Share Posted May 13, 2010 What does it sound like and run like when it hits that limit? Quote Link to comment Share on other sites More sharing options...
tjp Posted May 13, 2010 Author Report Share Posted May 13, 2010 It sounds like the revs are bouncing, a bit like when someone is revving a cold bike that hasn't warmed up properly and I guess it feels a little like that too. It stops pulling and as a result I need to carefully evaluate any climbs and pick taller gears that I wouldn't normally Quote Link to comment Share on other sites More sharing options...
t-shock 250 Posted May 13, 2010 Report Share Posted May 13, 2010 Sounds like a carburation issue. Quote Link to comment Share on other sites More sharing options...
tjp Posted May 13, 2010 Author Report Share Posted May 13, 2010 Sounds like a carburation issue. Thats what I thought but I've stripped and cleaned the carb and used the jetting recommended by Rathmells with little/no improvement. I have also tried larger main jets as I thought it could have been fuel starvation but had no change in the characteristic of the bike Quote Link to comment Share on other sites More sharing options...
stork955 Posted May 13, 2010 Report Share Posted May 13, 2010 Gday - is the air inlet restricted in some way? - over oiled filter for example? Your exhaust should be reasonable at this age but it might pay to have a look in there as well. Maybe repack the muffler at least. Cheers, Stork Quote Link to comment Share on other sites More sharing options...
tjp Posted May 13, 2010 Author Report Share Posted May 13, 2010 Gday - is the air inlet restricted in some way? - over oiled filter for example? Your exhaust should be reasonable at this age but it might pay to have a look in there as well. Maybe repack the muffler at least. Cheers, Stork Cheers Stork, I'll check these out Quote Link to comment Share on other sites More sharing options...
thespikeyone Posted May 13, 2010 Report Share Posted May 13, 2010 when does it do it, from cold or when hot???? have you checked fuel breather on tank. I had similar problem but it only happened when fan came on, it was the little black fan voltage reg, only a couple of quid. Quote Link to comment Share on other sites More sharing options...
copemech Posted May 13, 2010 Report Share Posted May 13, 2010 (edited) What size main jet is in it? Does it have stock reeds? Do you cary a spare coil in your backpack? Edited May 14, 2010 by copemech Quote Link to comment Share on other sites More sharing options...
zippy Posted May 14, 2010 Report Share Posted May 14, 2010 Do you cary a spare coil in your backpack? Never leave home without one, I carry a spare coil for everything I own. Coil of electrical wire. coil of tape coil of rubber bands coil of film (old school not that fancy digital HD stuff) coil of mechanics wire Just gotta be prepared Quote Link to comment Share on other sites More sharing options...
tjp Posted May 16, 2010 Author Report Share Posted May 16, 2010 Hey guys, I'VE FIXED IT!!!!!, thanks for the advice, Just thought you'd like to know what was causing this mysterious issue. As I said before the bike started and ran fine except at high rpm, where it wouldn't rev out. Well after going through the jetting, checking timing, rebuilding the engine and checking ALMOST every terminal for cleanliness and corrosion, I thought I Quote Link to comment Share on other sites More sharing options...
copemech Posted May 18, 2010 Report Share Posted May 18, 2010 Hey guys, I'VE FIXED IT!!!!!, thanks for the advice,Just thought you'd like to know what was causing this mysterious issue. As I said before the bike started and ran fine except at high rpm, where it wouldn't rev out. Well after going through the jetting, checking timing, rebuilding the engine and checking ALMOST every terminal for cleanliness and corrosion, I thought I Quote Link to comment Share on other sites More sharing options...
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