skid Posted May 9, 2007 Report Share Posted May 9, 2007 I have an 04 200. It does the engine knock thing. I've done the research and know there are a few different theorys on how to stop it. I was planning on going the decarbon route. The other day I forgot to bring my gas and bumed some fuel from a fellow rider who ran 50/50 race gas/premium. Needless to say the bike ran quite well as compared to the straight premium (93) it had in it. No engine knock. So my question is ... If carbon build up is the cause of the knock how come it did not knock with the 50/50 in it?? I would suspect the carbon would be just as hot in the motor weather or not you burn a 50/50 mix or straight 93. Word up!! Quote Link to comment Share on other sites More sharing options...
the addict Posted May 9, 2007 Report Share Posted May 9, 2007 Skid, higher the octane the less the knocking (pre ignition) probably nothing to do with carbon build up. Someone explained octane rating on here a while ago and basically the knock is caused by the fuel pre igniting in the cylinder under compression rather than the spark. Get yourself better fuel or octane boost and the problem should go. Quote Link to comment Share on other sites More sharing options...
skid Posted May 16, 2007 Author Report Share Posted May 16, 2007 I pulled the exhuast pipe off and took a look inside the cylinder. Damn thing is as clean as a whistle. Top of piston is a little brown but everything else looks mint. Could there be a build up on the dome but everything else would look mint?? Exhuast pipe wasn't bad either. Head pipe isn't all gunked up and mid pipe doesn't look too bad. Although I have no idea what a clean one looks like. I'll blast it with some heat tomorrow. Silencer packing was pretty gunked up though. Quote Link to comment Share on other sites More sharing options...
paulthistle Posted May 16, 2007 Report Share Posted May 16, 2007 The knock can be the result of combustion chamber design. The head can be reshaped to run knock free on whatever grade fuel you are running. Here is a website that can provide software to help make those calculations. Tom Turners Two Stroke Racing Most race fuels burn at a slower rate, so less knocking. Quote Link to comment Share on other sites More sharing options...
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