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Discussion Starter · #1 ·
After hearing all the info you gave Mike McD on rejetting my quad is doing every thing wrong. I am almost positve it is running lean. When I am riding it it back fires every time I get off the throtle. I need to rejet it but am kinda broke.I wanted to know what size jets to go with and if you could give me the run down on the best product for the money and the right way to replace them. My quad has an aftermarket foam air filter, spark arrestor taken out, and I am not sure but it might be bored .30 over the kid i bought it from said that he wasnt sure but it might have been.
 

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Yeah, if it's backfiring then it's probably lean. I know how to jet one, but Billy or Moose will probably be able to guess and get you closer than I would. I don't jet too often, because I mainly ride utility ATVs and I usually leave them stock.
 

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Do the plug test first to find out how far off you are with your jetting. Then post what size your running now. Ive slowly moded my 300ex and ive jetted it for about every step of the way. Should b able to help ya out bro.

Oh yeah a a little more detail on the mods airbox lid? Cam? Anything elts they may have done when they bored it that you kno about?
 

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130 main 40 slow jet 3 turns out from seat on the pilot. Your local honda dealer will sell them but you have to get the slow jet for a 300EX if I remember correctly? The cost is somewhere around 15.00 for the two you can't get any more budget than that.
 

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Discussion Starter · #6 ·
130 main 40 slow jet 3 turns out from seat on the pilot. Your local honda dealer will sell them but you have to get the slow jet for a 300EX if I remember correctly? The cost is somewhere around 15.00 for the two you can't get any more budget than that.
Yea thats awesome thanks I am going to go there tomorrow and ill just ask to get those sized jet. Thanks a ton!!!!!!!!
 

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My honda dealer couldn't get the pilot I needed so I just ordered it from Jets R Us.But I know your exhaust isn't stock and who knows what else isn't stock.But I'd also do a plug test and the 130 main and 40 pilot is probably gonna be real close.
 

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Discussion Starter · #8 ·
My honda dealer couldn't get the pilot I needed so I just ordered it from Jets R Us.But I know your exhaust isn't stock and who knows what else isn't stock.But I'd also do a plug test and the 130 main and 40 pilot is probably gonna be real close.
Hey yea I forgot about what he told when I bought it! it is a 400ex muffler it is all welded up to fit the 250x
 

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That would still be concidered a stock muffler so 130 will be real close I would suggest getting a 128, 130, and a 132 2 or 3 new plugs and start testing. the slow jet is going to work.
 

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Discussion Starter · #10 ·
ok so with plugs how what do I need to get do I test the gap or what to get sizing?????????I have never delt with plugs just replaced what it has been running
 

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Most of todays plugs are pregapped I think it's .035 not sure without looking. as far as checking for proper jetting.........
Start the quad ride it around some get it good and warmed up then find a long straightmake a wide open pass away from your work area then on the way back do the same only this time when you get on top reach over and tur it off while on the throttleonce you turn the switch off pull in the clutch and let off the throttle and coast (engine off) to your tools pull the plug..You are looking for a nice medium to dark tan, like a piece of cardboard or coffee with creamer. if it's too white go up on the main jet if it's black remove the air box lid toss it on the ground put in a new plug and run it the same way. if it's still too dark drop down one jet and put the lid back on and put in another new plug and do it agaian. It takes time to rejet but once you get it right you will feel a difference. Keep in mind it is much much better to have a dark looking plug over real light. too lean will melt a piston. good luck let us know what you find. FYI you do not have to remove the carb to change the main jet. just pull the bowl cap off the bottom and you can access it there and do not overtighten!!! very thin BRASS!!
 

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Discussion Starter · #12 ·
ok thanks for clearing that up cant wait to see the power i know my quad has more than it shows!!!(still hauls now)
 
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