dazzagreener Posted November 16, 2011 Report Share Posted November 16, 2011 Hello Iv noticed that my bike makes a very faint engine knock when doing climbs ect and also if i go flat out across a feild and as soon as i let off to slow down the bike stalls and takes a while to start agian. my fuel mixture is 64ml for 4 litres the carb is set up as standard for a 2002 this is from the service manual 33 pilot 126 main 3.5 turns on the air mixture 3rd notch on the pin i noticed that on the 2009 service manual that all the settings are the same but they use 122 main jet instead can anyone explain should i change mine to this, would it help with my problems hope someone can help me cheers Darren Quote Link to comment Share on other sites More sharing options...
stump magnet Posted November 16, 2011 Report Share Posted November 16, 2011 (edited) Hello Iv noticed that my bike makes a very faint engine knock when doing climbs ect and also if i go flat out across a feild and as soon as i let off to slow down the bike stalls and takes a while to start agian. my fuel mixture is 64ml for 4 litres the carb is set up as standard for a 2002 this is from the service manual 33 pilot 126 main 3.5 turns on the air mixture 3rd notch on the pin i noticed that on the 2009 service manual that all the settings are the same but they use 122 main jet instead can anyone explain should i change mine to this, would it help with my problems hope someone can help me cheers Darren the smaller main jet would make it worse,it sounds like its running lean. if it ran fine before then it could be fuel starvation, this could be caused by the follwing, blocked fuel tap or filter, sticking float or float needle, tank not venting or carb vent tubes blocked. check these first then try raising the needle to middle clip to run a little richer, (you can also give it a little choke once warmed up as this will enrichen the mixture a little to see what difference it makes) if its better then the jettings needs richening if worse then the oposite Edited November 16, 2011 by stump magnet Quote Link to comment Share on other sites More sharing options...
splatshop Posted November 16, 2011 Report Share Posted November 16, 2011 Hi Some Sherco came with a 200 float valve this would cause the problem you are experiencing, so check to make sure you have a 250 or even a 270 (if you like going flat out a lot) float valve in your carb. You can purchase a dellorto float needle valve here. Other things to check are, make sure the breather pipe is clear and nothing is causing it to block. Hope this helps. Chris Quote Link to comment Share on other sites More sharing options...
outlaw dave Posted November 16, 2011 Report Share Posted November 16, 2011 Check the gas tap -Stand pipe in the gas tank - you need to remove the gas tap - sorry petrol tap - on some ealier bikes this plastic tube was too long and caused lean conditions. - before doing this try running the bike with the tap on the reserve position. - you can check all the service data by clicking on www.shercousa.com Note ! We always fit a larger pilot jet - 35 or 36. Quote Link to comment Share on other sites More sharing options...
copemech Posted November 17, 2011 Report Share Posted November 17, 2011 I was on a #38 pilot befor I ever got my '07 to stop pinging on accel. Seems from feedback, many have not need to go that high, specially in UK with their fuel, yet I never though I would need it either, yet seems some of this varies with the carb and so on. The alcohol contents of most fuels seem to influence this I think, which may also vary. All point being, never presume a 36 will fix this, based upon my experience! Mix set accordingly, was sweet after that with the Dellorto, till I changed, then start over with the OKO, which ironically enough ended on the #38 as well. Quote Link to comment Share on other sites More sharing options...
dadof2 Posted November 17, 2011 Report Share Posted November 17, 2011 It can be a natural feature of two stroke carburation (due to pulsing through the carb at low / medium RPM which does not occur flat out) that they run weak at the top end. From you symptions you certainly need to richen the bike across the whole rev range (assuming timing and plug correct). You plug colour should give an indication of rich / lean. 60:1 (68:4000)is very little oil for sustained high speed blasts whatever type of oil you are using. Cheers Quote Link to comment Share on other sites More sharing options...
ham2 Posted November 18, 2011 Report Share Posted November 18, 2011 Is it running hot? Quote Link to comment Share on other sites More sharing options...
robbybobby Posted December 3, 2011 Report Share Posted December 3, 2011 Maybe just too low octane in fuel? Did u ever figure it out? Quote Link to comment Share on other sites More sharing options...
dazzagreener Posted February 27, 2012 Author Report Share Posted February 27, 2012 iv still got the problem!!! i think the bike runs lean because a way to start it again when it cuts out going acoss a feild it to put the choke on. also when it starts it revs up very high like its lean. i but a new plug in hoping this would solve the problem cheers Quote Link to comment Share on other sites More sharing options...
totalshell Posted February 28, 2012 Report Share Posted February 28, 2012 use super unleaded rather than normal unleaded as a simple fix that worked on my beta Quote Link to comment Share on other sites More sharing options...
copemech Posted February 28, 2012 Report Share Posted February 28, 2012 iv still got the problem!!! i think the bike runs lean because a way to start it again when it cuts out going acoss a feild it to put the choke on. also when it starts it revs up very high like its lean. i but a new plug in hoping this would solve the problem cheers If it does this just running accross a field, yet ok normally or just short run, one would want to insure fuel is flowing properly. A pinchet vent tube or stuck vent to the tank cap can cause a vacume in the tank. A blocked screen on the petcock valve could restrict proper flow. With a Dellorto the banjo filter on the carb could do the same. Then there is the float valve as Chris stated. A #250 min. The fuel must flow reliably, lest it runs out. It is easy enough to ck these things. Quote Link to comment Share on other sites More sharing options...
dazzagreener Posted February 28, 2012 Author Report Share Posted February 28, 2012 If it does this just running accross a field, yet ok normally or just short run, one would want to insure fuel is flowing properly. A pinchet vent tube or stuck vent to the tank cap can cause a vacume in the tank. A blocked screen on the petcock valve could restrict proper flow. With a Dellorto the banjo filter on the carb could do the same. Then there is the float valve as Chris stated. A #250 min. The fuel must flow reliably, lest it runs out. It is easy enough to ck these things. Thanks mate i will look in to this. i did check the vlave on the tank thats ok. also iv checked the float valve thats ok to and cleaned the banjo filter. i will look at the fuel tap filter tonight hopfully. also what mixture should i run i normally do 60:1 but a mate of mine with the same bike does 75:1 cheers Quote Link to comment Share on other sites More sharing options...
nelly1 Posted March 3, 2012 Report Share Posted March 3, 2012 i would run it 80:1 with super unleaded fully synthetic oil Quote Link to comment Share on other sites More sharing options...
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