79DT250 Posted June 9, 2013 Share Posted June 9, 2013 So i recently bought my dt 250 and it was running great for a few days and then it died, I finally got it started up the other day and it wont go past 4k rpms when im driving it. ive tried everything i can think of with the carb and i can get it running good for about 10 minutes. it idles just fine just not when driving it? it leaks from the head gasket? idk if maybe a vacuum leak or something would be causing my problem. Link to comment Share on other sites More sharing options...
UK_DT Posted June 10, 2013 Share Posted June 10, 2013 Could well be the crankshaft seals. The LH side one, beneath the magneto, sucks in air once the engine is warmed up if it has hardened, making the engine run lean. The RH side one will suck in oil.My 400 runs fine until it's warmed up, then starts spluttering, doesn't run smooth on the overrun and general becomes a pig! Sadly a flat renovation is taking priority until it's ready to rent out (by which time summer (in the UK at least) will probably have passed.The LH one is an easy replacement (or so I believe). Once done, make sure the carb is correctly jetted (taking into account altitude), the float is free to move (mine was stuck) and give it a de-coke (if you haven't already done so).Then, happy riding!! Link to comment Share on other sites More sharing options...
blackhat250 Posted June 10, 2013 Share Posted June 10, 2013 Also" have you checked flow of fuel. whip of pipe to carb, let it run for a moment, sounds like fuel starvation,, Link to comment Share on other sites More sharing options...
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