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Discussion Starter #1
Hello guys so I bought my bike recently and it came with Vance and Hines straight shots and a spiked air intake. When I bought it it started good and idled good but when I accelerated it would backfire and if I went over 35 mph it would have a real hard time accelerating. So knowing the problem was a lean mixture I bought the proper Vance and Hines carb jet kit for my pipes and it told me for my pipes without baffles which it has none put in a DJ136 main jet and take out my DJ134 jet I already had in there and put the air mixture screw 3 and a half times out. So I did all of that and when I started my bike the carb was popping and bike was backfiring and it was idling really high. So I figured it was too rich and put the air mixture screw 3 times instead of 3 and a half times. So now the bike wasn't popping but it wouldn't stay idling without choke on and moment u closed it, it would die. So Idk if i go back to the original jet and adjust the mixture screw or put one jet higher DJ138? Asking for help
 

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if you mean original jet is your MJ (main jet)?, that MJ main jet has no function at idle or at 35 mph
 

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if the bike backfires out back thru the carb, that's a sign of the fuel mixture being lean
 

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what is your pilot Jet (PJ) size?
 

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Discussion Starter #5
I have no clue what my pilot jet size is but at first before kit it would idle fine but run like crap after 35 mph.and now it won't even run without the choke with new main jet. The kit didn't come with a pilot jet
 

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when you say kit do you mean a jet kit with a needle and main jets? is this a dynojet jet kit? did you remove the 800 stock needle and installed the jet kit needle? and if you did install a jet ket needle, what notch from the top did you set the e-clip? and your airbox is a spike? those jet kits come with jets stamped with a DJ and a number on them, if it's a Dynojet Jet Kit jets you installed then the equivalent Keihin Main Jet size as follows-
DJ126=Keihin#135
DJ130=Keihin#140
DJ134=Keihin#145
DJ138=Keihin#150
DJ142=Keihin#155
DJ146=Keihin#160
DJ150=Keihin#165
DJ154=Keihin#170
DJ158=Keihin#175
DJ162=Keihin#180

I don't know what size Keihin main jet should be with a spike air intake but my open type air intake has a Keihin#170 main jet, with a stock 48 Pilot Jet (leave your Pilot Jet stock),
when your bike idled ok at first and then it ran not-so-good at 35mph, that sounds like a problem is with your carb needle, because its the needle that controls your mid-range throttle position and 35mph is mid-range throttle
 

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Discussion Starter #7
I did replace the jet needle with my kit needle and put it on the 2nd grove as recommended from the kit instructions. It's a Vance and Hines stage 1 carb kit. So I'm going to take out the new jet and put the old one back it and place the needle at grove 3 and see what happens.
 

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Discussion Starter #8
Update: put the old jet back in was still popping even with the het needle at the 4th grove and it wasn't idling either. Just put the the 136 back in this time also with the 4th grove jet needle but won't idle still with new jet. And the air mixture screw both times where at 3 and a half turns.
 

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when trying to get your bike to idle properly, the needle and that 136 MJ have no function, so adjusting the e-clip on the needle or changing MJ sizes will not change the condition of the idle, what affects idle is #1 PJ size, #2 pilot mixture screw setting and #3 airbox, because for idle to work good you need the fuel mixture to be right to combust, and numbers 1 2 and 3 will affect fuel mixture for idle, put the e-clip on the needle in the 2nd grove from the top, check to see if your PJ is a stock 48, set your pilot mixture screw at 2.75 turns out from seat, remove the kit DJ main jet and put in a Keihin #170 MJ (main jet), remove that spike air intake, and try running your bike without it that way and see how it runs
 
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