markkeen123 Posted February 23, 2009 Report Share Posted February 23, 2009 hi all i have a small problem i think but need some advice from people that have ownd a rev 3 2005 250 for a while. the problem is when the throttle is reved up then releaced the engine knocks as it is slowning down does any one know the carb settings for the mixture screws. does the bike run alot better on super unleaded thanks wb from mark Quote Link to comment Share on other sites More sharing options...
feetupfun Posted February 23, 2009 Report Share Posted February 23, 2009 Yes your problem is probably with your fuel. Rev 3s tend to do that on fuel that is too old or is too low an octane rating. You can reduce it by optimising your pilot jet size but if you use good fuel you will probably not have to do anything else. Quote Link to comment Share on other sites More sharing options...
markkeen123 Posted February 23, 2009 Author Report Share Posted February 23, 2009 what about trying octane increaser????? Quote Link to comment Share on other sites More sharing options...
dan williams Posted February 23, 2009 Report Share Posted February 23, 2009 Good gas is essential due to the high compression ratio. If you can live with a little less pop from the engine you can throw another base gasket in to drop the compression ratio a bit. Adjusting the pilot or retarding the ignition will also lower the tendancy to knock but they will have the effect of making the bike somewhat less responsive. Octane booster will probably work but you're dealing with an unknown quantity there. Personally I like race gas because it's consistant. But yeah it's expensive too. Quote Link to comment Share on other sites More sharing options...
paul w Posted February 23, 2009 Report Share Posted February 23, 2009 i had a 2005 250. same problem. pre-detonation. i cured mine by going down one size on the main jet. fitting boysen reeds (a big difference) needle in the std position and std pilot jet. sorry i cant remeber the sizes, call lampkins they will tell you. but the main problem was it needs a de-coke, head barrel, piston off. do a proper job and get the top end spotless. i ran a 5 plug this time of year and a 6 when it warmed up a bit. it only occasionally 'pre-detonated' on long part throttle uphil climbs, but that was it. Quote Link to comment Share on other sites More sharing options...
markkeen123 Posted February 23, 2009 Author Report Share Posted February 23, 2009 do you have the standard carb settings i was told 1 1/2 turns out ???? Quote Link to comment Share on other sites More sharing options...
paul w Posted February 23, 2009 Report Share Posted February 23, 2009 the turns out depends on each specific bike, its jetting and other factors, 1.5 turns out is a good starting point, but wont cure your problems. Quote Link to comment Share on other sites More sharing options...
totalshell Posted February 23, 2009 Report Share Posted February 23, 2009 solved my 'knockin' by using the premium unleaded from any petrol station. only costs 5p more. i tried the decokes but it made no difference. do the cheapest thing use more expensive fuel.. Quote Link to comment Share on other sites More sharing options...
mikey_boy Posted February 24, 2009 Report Share Posted February 24, 2009 Yeah, its always best to run them on premium anyway, Im pretty sure the betas owners manual specs that you only use premium unleaded. It does in mine anyway, cheers Quote Link to comment Share on other sites More sharing options...
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