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  #1  
Old 02-21-2017, 05:41 PM
Weekend Warrior
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Default Help !! Polaris predator 500 misfiring after carb rebuild

Hi im new to this forum so hoping a few people can shed some light on my problem

I have a 2004 Polaris predator 500 which i recently purchased

The previous owner had left the fuel on for 8 months while the quad was in his garage not in use . In that time petrol had mixed with the oil , oil drained and fresh out in I could still smell fuel . The quad run perfect wasn't misfiring or anything, started on the button no smoke etc

I was told to do a carb rebuild and another oil and filter change to be on the safe side

The previous owner had also fitted a dyno jet kit with a k&n air filter cone ! (Not panel filter) with a 170 main jet and dyno jet needle set on the second setting also something on the slider with the need had to be drilled with and extra hole which is part of the carb mod to allow the needle to lift quicker .

So the bike was booked in with my local atv shop to have a full carb rebuild to stop the fuel getting in the oil . Keep in mind the quad ran absolutely perfect apart from the fuel mixing in the oil .

So they rebuilt the carb and the quad didn't run as it should was bogging out as soon as you touch the throttle , so they contacted me to tell me it was what was going on , I then mentioned if they had put the dyno jet needle jet back in , they had kept the 170 jet in but not the needle . So they then put the dyno jet needle and 170 main jet in and it was still not right . They then fitted a 165 main with the dyno needle and was better but no right , it its back firing at bogging on 1/4 throttle but fine on wide open throttle.

They are trying to tell me that they need to upgrade the pilot jet from a 45 to a 47.5 or maybe a 50 .

They have put the carb back to the way it was when I first took it to the shop apart from from seals o rings and the float so it's back the way it was when it first went there with the 170 jet in and dyno jet needle set on the second setting , the only difference is it's still not running right .

Why would they need to upgrade the pilot jet if it ran perfect when it went in there with a standard pilot ?

woukdnit be that they haven't adjusted the float correctly ?

Really hope someone can help with this
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Old 02-21-2017, 05:53 PM
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First question is the air box lid on with the K&N filter?If not this could be a big part on jetting. Not a fan of Dynojet kits because they mark their own jet sizes and they don't correspond to Mikuni or Keihin sizes.My two cents is put it back stock with the standard main and pilot jet and needle and go from there.Another problem on the Predator is people forgetting to check valve clearances. Shim under bucket system that can cause problems if the valves are too tight.
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Old 02-21-2017, 05:58 PM
Weekend Warrior
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There is no lid on the k&n as it just connects straight to the carb it's not pannel filter the standard air box has been taken out completely. I wouldn't think it is the valve clearances or shims as it was running spot on before it went in for a carb rebuild . I just don't understand how it could go in for a rebuild , the 170 main and dyno needle put back in and it still not running right . Is there anything that could of gone wrong during the rebuild incorrectly adjusted float etc ?
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Old 02-21-2017, 06:12 PM
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Quote:
Originally Posted by old polaris tech View Post
First question is the air box lid on with the K&N filter?If not this could be a big part on jetting. Not a fan of Dynojet kits because they mark their own jet sizes and they don't correspond to Mikuni or Keihin sizes.My two cents is put it back stock with the standard main and pilot jet and needle and go from there.Another problem on the Predator is people forgetting to check valve clearances. Shim under bucket system that can cause problems if the valves are too tight.
There is no lid on the k&n as it just connects straight to the carb it's not pannel filter the standard air box has been taken out completely. I wouldn't think it is the valve clearances or shims as it was running spot on before it went in for a carb rebuild . I just don't understand how it could go in for a rebuild , the 170 main and dyno needle put back in and it still not running right . Is there anything that could of gone wrong during the rebuild incorrectly adjusted float etc ?
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Old 02-21-2017, 06:15 PM
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Anytime you alter air filters,remove air boxes,install Dyno jet kits(mainly you're paying for that titanium needle) it's hit or miss as far as it running right. Most of the time you still have to play with jetting,etc. Possible that the guy or guys working on it didn't know what they were doing either.All I can say is recheck the carb and their work.Plus the manual can help on the carb or any other problems.http://polaris-atv.brssm.com/2004-Po...ce-Manual.html
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