Questionwell the engine just rebuilt to try to find the prob. the piston's were changed "pure Polaris" of course and the brake cleaner was used every where never sucked in any but changed the seals wile the engine was apart. the plugs are coming out light brown, the backfiring is only on one side, on the mag side only and its not the carbs because in switching the carbs from side to side the prob should follow it, it does not, stays on the mag side. running super gas in it nothing else added. Thanks
Well with the cdi box I had another one off another Polaris to try, put it on and did the same thing. I'm going to give the jet a different size on that side but the thing i don't understand is that the 2 spark plugs are coming out a nice light brown and it is backfiring out the exhaust.
I have been told by others that maybe my crank could be twisted but there is no strange vibration in the engine, but then again it only takes a little twist what are every one thoughts on that?
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ok he i go you will get a kick out of this. well to start off last year my Polaris 700 xc 1999 started to backfire wile riding it below 6000 rpm anything over no problem. ok here is what we tried so far 1st thing the carbs off and on/rebuilt so many times i lost count same with reeds even from switching them side to side same problem on the mag side never the clutch side ok next thing tried everything with the elcital from disconnecting every thing to the timing every thing was right on next seals and gasket set for the hole engine at a dealer next new kit in gas pump ok now is where i am with 2 dealers telling me I'm on my own they have no clue what the hell is wrong with it and me left trouble shooting it all my self with friends now i come to see that running with the choke on runs like shit but no backfiring its getting weird that is where i am now help with anything in your mind or another trouble shoot try any info could solve the problem Thanks
P.S. ask if need more info
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Check you compression and get back to me. Depend on how hard it's been rode you may need a ring kit.
AnswerYou just answered your own question. I am willing to bet the crank is twisted. I never thought of that until you metioned it. I had a 95 XCR 600 that the crank twisted at 900 miles. I didn't vibrate or anything. It just ran like shit. It only takes a little twist to through everything off. A good shop should be able to sraighten it. The pins have to be heated then turned back straight. Hopefuly you don't have to replace the pins because that can be pricey. And believe it or not this is a common polaris problem. The triples are really bad.
