dcole5 Posted November 8, 2011 Report Share Posted November 8, 2011 I live at 6000ft elevation and trying to jet the 2012 290 Sherco. I have everything stock and put in a 118 main jet. (125 is stock) Seems to be pretty good, the plug is a light brown and all is good except it really seems to be starving for gas at really high RPM's going down the road. I might try a 120 main, but just wondering what everyone else is running at this altitude range. Overall the bike is truly amazing ! Thanks Quote Link to comment Share on other sites More sharing options...
chewy Posted November 8, 2011 Report Share Posted November 8, 2011 it may be the fuel inlet (float needle) jet size; there was a spate of problems a while back when flat out down the road it "runs out of fuel" let it tick over for a moment and hey presto.????????????? only a casual thought. Quote Link to comment Share on other sites More sharing options...
outlaw dave Posted November 8, 2011 Report Share Posted November 8, 2011 Fit a larger pilot jet. Quote Link to comment Share on other sites More sharing options...
splatshop Posted November 9, 2011 Report Share Posted November 9, 2011 it may be the fuel inlet (float needle) jet size; there was a spate of problems a while back when flat out down the road it "runs out of fuel" let it tick over for a moment and hey presto.????????????? only a casual thought. The 2012 Sherco has the Keihin PWK fitted so it's not to do with the float needle valve. dcole5 sorry we haven't tried the bike at high altitude but from passed experience you usually use a smaller main and a slightly larger pilot but possibly you have gone to small on the main jet. Quote Link to comment Share on other sites More sharing options...
dcole5 Posted November 14, 2011 Author Report Share Posted November 14, 2011 I will check out the fuel inlet float jet. This sure seems like the symtom. Thanks for the tip Quote Link to comment Share on other sites More sharing options...
splatshop Posted November 15, 2011 Report Share Posted November 15, 2011 I will check out the fuel inlet float jet. This sure seems like the symtom. Thanks for the tip You cannot change the float needle valve jet size on the PWK as it is machined in to the casting of the carburettor. I think you need to try a 120 main or if that doesn't help then maybe try a washer under the needle. Quote Link to comment Share on other sites More sharing options...
copemech Posted November 16, 2011 Report Share Posted November 16, 2011 You cannot change the float needle valve jet size on the PWK as it is machined in to the casting of the carburettor. I think you need to try a 120 main or if that doesn't help then maybe try a washer under the needle. This does make me wonder a bit, as he states "starving" running down the road at high rpm! Couple of things come to mind, firat is this immidiate, or does it seem to run out of fuel after a short distance? Second thought being, the bike may well still have the fuel pump surge orface in the carb inlet line, which is a flow limiting device, ad I think basically put there for good reason on the dellorto to help control the float valve under a pressure feed. Sems the Kiehin float valve works better in a control aspect, yet the inline surge orface if smaller than the total demand of the Kiehin jets could be restricting things on the road at high rpm. I do not doo high speed roadwork on any of them so this is just a guess(thought), yet I did think I recall someone increasing the orface size on the Dellorto equipped bikes, so same principal may apply. Thoughts, Chris? Quote Link to comment Share on other sites More sharing options...
dcole5 Posted November 16, 2011 Author Report Share Posted November 16, 2011 It is a short distance before starving for fule. It does seem to be a fuel pump related issue. Not worried about going hard on a road, but what happens when I have a hill climb section at a trials ? I will check all the fuel inlets on the carb. In the mean time, perhaps a 120 main will help a bit, but if there is no fuel in the float this will not make a difference. Thanks for the insight This does make me wonder a bit, as he states "starving" running down the road at high rpm! Couple of things come to mind, firat is this immidiate, or does it seem to run out of fuel after a short distance? Second thought being, the bike may well still have the fuel pump surge orface in the carb inlet line, which is a flow limiting device, ad I think basically put there for good reason on the dellorto to help control the float valve under a pressure feed. Sems the Kiehin float valve works better in a control aspect, yet the inline surge orface if smaller than the total demand of the Kiehin jets could be restricting things on the road at high rpm. I do not doo high speed roadwork on any of them so this is just a guess(thought), yet I did think I recall someone increasing the orface size on the Dellorto equipped bikes, so same principal may apply. Thoughts, Chris? Quote Link to comment Share on other sites More sharing options...
copemech Posted November 17, 2011 Report Share Posted November 17, 2011 It is a short distance before starving for fule. It does seem to be a fuel pump related issue. Not worried about going hard on a road, but what happens when I have a hill climb section at a trials ? I will check all the fuel inlets on the carb. In the mean time, perhaps a 120 main will help a bit, but if there is no fuel in the float this will not make a difference. Thanks for the insight So it accellerates well initially at WOT and then after a short run at higher speeds it does this? Would you consider it e "bog" or near total los of fuel? As if the bowl is running out? Have not heard from Splatshpo Chris on this as yet, but if that restricter is in the feed line, there could be some swarf in it which would not allow proper flow of fuel to the carb. Quote Link to comment Share on other sites More sharing options...
michael martin Posted November 17, 2011 Report Share Posted November 17, 2011 A restrictor in the fuel line??. Does a 2012 2.9 have one or has Sherco done that in the past? Quote Link to comment Share on other sites More sharing options...
copemech Posted November 17, 2011 Report Share Posted November 17, 2011 A restrictor in the fuel line??. Does a 2012 2.9 have one or has Sherco done that in the past? Short answer, YES! it seems! As I have not owned one, I have little experience with the item in question, why do you ask, you Gassr riding CS/!(ala Phillip) Quote Link to comment Share on other sites More sharing options...
splatshop Posted November 17, 2011 Report Share Posted November 17, 2011 There is no restricter in the 2012 model, so this isn't your problem. To be honest it sounds to me like you have just gone a little to far with leaning the bike off and you need to try richening it up a bit. Other things it might be are a blocked breather or the one way valve, it might be worth cleaning the tank and fuel pump. Quote Link to comment Share on other sites More sharing options...
splatshop Posted November 17, 2011 Report Share Posted November 17, 2011 A restrictor in the fuel line??. Does a 2012 2.9 have one or has Sherco done that in the past? The 2011 Sherco came with a restrictor in the fuel inlet boss on the VHST carburettor, it was just a small piece of aluminium pressed in place with a 2.5mm hole through the middle. Quote Link to comment Share on other sites More sharing options...
dcole5 Posted November 17, 2011 Author Report Share Posted November 17, 2011 I agree, easiest thing to try is a 120 main and see what happens. It runs perfect right now and big revs for a splatter are ok, it is only after a bit on a big hill or road and yes, it seems like it just is running flat and starved for gas. Plug reading is a light brown. I will clean tank and carb and fuel pump also.. Thanks !! There is no restricter in the 2012 model, so this isn't your problem. To be honest it sounds to me like you have just gone a little to far with leaning the bike off and you need to try richening it up a bit. Other things it might be are a blocked breather or the one way valve, it might be worth cleaning the tank and fuel pump. Quote Link to comment Share on other sites More sharing options...
michael martin Posted November 17, 2011 Report Share Posted November 17, 2011 Mark, I have gone to the dark side......Haha. I am trying a 2012 2.9 and can't seem to get it to run like I want it, right when you touch the throttle. So just over idle maybe 1/32 throttle. I have tried 42,45,48,50 pilots. JJH(stock) JJJ, JJG, JLH, JFJ, JLG needles. Float level is good. Any Idea's?? Quote Link to comment Share on other sites More sharing options...
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