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Discussion Starter · #1 · (Edited)
my 94 Polaris Sport 400L 2 Stroke is having some major misfiring issues. Just rebuilt the carb and fixed all the air leaks and it wouldnt idle or staying running so we had to make the pilot jet .004" bigger and now it idles perfectly but it misses throughout the entire rpm range. I tried a new spark plug, replaced the coil and wire and leaned out the oil/fuel mixture incase there was too much oil fouling out the plug right away and still misfiring badly.The metering rod that has the notches on it to adjust how rich/lean it runs is set a the richest setting which probably is why it is running very rich. Would being to rich cause a constant mis throughout the rpm range? partial or full throttle it just putters. It seems like ignition problem to me but the igntion is working fine. any suggestions?
 

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LOW COMPRESSION!!!! If you say you had air leaks, then most likely at some point it was running too lean and probably smoked the piston rings. K had a vey similar prob. and turned out to be bad rings
 

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Discussion Starter · #3 ·
no the compression is fine. Everything worked fine before, but it just wouldn't idle, so we rebuilt the carb and fixed the replaced the boot from the carb to reed valve which was torn. We drilled out the pilot jet .004" which fixed the idle but after the carb rebuild is when it started missing
 

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Discussion Starter · #4 ·
I put the stock pilot jet back in and that fixed the misfiring problem but now its bogging down. Soemtimes it works perfect and really moves and then it just start to bog down when u give it throttle. Does anyone know if the main jet in the carb is the primary fuel delivery jet in the carb or just a power adder for high rpm applications? Does the pilot jet(idle jet) control most of the fuel and if it needs alittle more the main jet adds more fuel in?
Im having a hard time getting this dialed in and tuned perfectly. with the stock pilot jet in, i put the metering rod at the richest setting notch and with that, it still was misfiring, not nearly as bad as before but it still is to much. So i droped the rod down one notch to lean it out alittle more and now its bogging down. I cant seem to get it in a happy medium
 

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did you ever figure out what your issue was. I did a carb rebuild and have ran into the same problem. I either can't get the machine to idle or when i do it bogs down when i hit the throttle or dies completely. thanks
 
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