betarob Posted July 21, 2009 Report Share Posted July 21, 2009 Hey there, I've got a 2009 125 gasser and it suffers with the seemingly usual, misfiring problem. Specs: (maybe add-ons could be cause?) Keihin 28 mm carb, Boyesen reeds, raga inlet manifold We run the bikes on a 70:1 mix which is fairly lean i suppose, but when its not misfiring it runs so so cleanly and sweetly. The bike will run absolutely great and then start misfiring and backfiring, even sometimes with flames out of the exhaust! If the bike is then revved until nearly ceasing it clears and runs fine again. It is maintained extremely highly with the filter/crab cleaned after every virtually every trial. Could anyone shed some light on the diagnosis and treatment of the problem? Thankyou Rob Quote Link to comment Share on other sites More sharing options...
123lancei Posted July 21, 2009 Report Share Posted July 21, 2009 i know it sounds basic but start by just changing the plug. and try the bike again. if it still does it, it sounds like ignition. but what part of it i dont know. i did have a 125 beta 2007 and that suffered from missing on the bottom end but only when it got hot. turned out it was the stator. theres a bloke in spain who can xray the stators to find out if there is something wroung with them then he fixes them. cost just under Quote Link to comment Share on other sites More sharing options...
gasgas4life Posted July 21, 2009 Report Share Posted July 21, 2009 Check that the earth's bolt is tight and they havn't come apart. When i had my 07 125 gasser i had a simiular problem and it turned out that the earth bolt had fallen out, causing it to misfire. Just a thought Quote Link to comment Share on other sites More sharing options...
pandelboy Posted July 21, 2009 Report Share Posted July 21, 2009 Ian,check the small earth wire from cdi to frame . still coming out of the factory too short and can break easy. Quote Link to comment Share on other sites More sharing options...
shercoman2k8 Posted July 22, 2009 Report Share Posted July 22, 2009 As said, check all earths and wiring, then check your timing, could be causing the backfiring, retarded to far? Also could be a jetting and carb setup issue... You will get backfiring if running to lean! Quote Link to comment Share on other sites More sharing options...
gasgasian Posted July 25, 2009 Report Share Posted July 25, 2009 any more help please? Its really important! Thankyou Rob Quote Link to comment Share on other sites More sharing options...
b40rt Posted July 25, 2009 Report Share Posted July 25, 2009 Change your fuel, drain and blow out carb, fresh fuel. Quote Link to comment Share on other sites More sharing options...
gasgasian Posted July 25, 2009 Report Share Posted July 25, 2009 it has been doing this for some time now. It works ok for a while when the plug is changed. What is this an indication of? plug break down? Thanks Rob Quote Link to comment Share on other sites More sharing options...
gasgasian Posted July 26, 2009 Report Share Posted July 26, 2009 hey there, We got it sorted it was the boyesen reeds! Put the standard reeds in and its fine! works great! Thanks for the help, Rob Quote Link to comment Share on other sites More sharing options...
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