jetting issues

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cmusselwhite

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I bought an hmf slip on, k&n air filter and dyno jet kit. followed the instructions. running lean, road it for 7 mins tonight and header was red... put in 148 main and needle on 4th groove. wants to stumble and pop at 500-1500rpm, after that runs good at 1/4-full throttle, if i run it up hard to wot and chop the throttle it wants to pop and backfire, also having some plames out the tail pipe. i read the long "how to jet thread" and learned a few things i didnt know, so i ordered a 45 pilot jet, when it comes in a am going to install it and the 150 main jet. if no luck after that, should i move the needle to the 3rd groove?? also my airbox has the lid and no holes in it. no other engine mods done.. any help will be appreciated. going racing the 17th and 18 of dec.. so hope to hear something soon.
 
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I would move the needle clip back to the 3rd postion from the top and If I where you I would have bought regular main jet's because the dynojet main jets are actually smaller than the oem equivalent also you should probaly adjust your idle air mix
 
YEa i wish i would have read a little more before i bought it. JETSRUS.com has a good kit for like $31.. i may buy it. and i have backed it out almost as far it can..
 
and when you say 3rd groove, do you mean 3 down from the top(flat spot) of the needle?
 
the more you back it out the leaner that the idle circut runs = more heat when idling and at 1/4 throttle set to factory at 2-2.5 turns out
 
georgia, so under 3000, and so i need to tighten the screw.. lol well damn. i thought loosening it would add more fuel. thanks for your help man
 
I would move the needle clip back to the 3rd postion from the top and If I where you I would have bought regular main jet's because the dynojet main jets are actually smaller than the oem equivalent also you should probaly adjust your idle air mix

What he said.
 
with the screw in as far as i can get it while still installed, it doesnt want to idle long. still hesitant at idle to 1/4 throttle... i think it is the pilot, or the needle..
 
the more you back it out the leaner that the idle circut runs = more heat when idling and at 1/4 throttle set to factory at 2-2.5 turns out



No, when you turn it out you are richening the mixture. In is lean. If the screw was on the air box side of the carb then out would be lean, in would be rich.
 
ok thanks. i had it out and it ran a little better. i apreciate all the help guys!!
 
this might help it's mikuni vs dynojet vs keihin sizes
dynojetvsstock.png


dean should i add this to the getting to how your carb thread
 
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