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Discussion Starter #1
howdy folks - just got a 2003 scrambler 500, wondering about carb jetting etc. i think the stock jets are a 152.5 and 40, but this machine has an aftermarket muffler, white bros i think it is... and i'm planning to put in a better filter also. what kind of jetting should i start with? i'm not sure whats in there, but it seems to backfire a bit, so i'm going to go through the carb and just get it set so i know where i'm starting at.... and what about the needle, is it adjustable on these or should i shim it? i guess my question is with a muffler and filter where about should i be with main, pilot and needle jets and where should i set air screw? thanks a lot to anybody with a little guidance on this and cheers to all.
 

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Discussion Starter #2
seriously? nobodies put a muffler and air filer on one of these? c'mon, somebody please point me in the right direction........
 

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I have a scrambler but it is still bone stock. My experience is that if you put an aftermarket air filter and pipe, it increases the air flow, that means you have to install larger jets for more fuel to balance out the fuel air mixture. A 160 main jet and the air/fuel screw about 2 turns out from seated should do the trick. If it starts to run worse, back off and go down a little bit.
 

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I would go up one jet size at a time , read your plug as you go, might be alright with whats in it, jet sises go by 2.5, as in 152.5 to 155 to 157.5
 

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With my 07, I installed this kit, 1998-2009 Polaris 500 Scrambler Speed Kit when I was stationed in WA state at sea level. After a few, first attemps at jetting, took it to my local, trusty dealership. In May of 2010, I transfered to Fallon, NV. not only having to deal with elavation but seasonal temps for jetting. Sorry for blabbing, but purchased Dynojet kits for all my quad, piece of cake, I've become a "jet I master". Sorry, that just flowed out. All my quads run like raped apes.
 

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I have a mod exhaust, uni filter with 1" mods and titanium header wrap running a 160 main from a stock 155. One turn on idle screw plug looks great no back firing starts perfect in any weather

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