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idiot_on_426

jd jet kit

11 posts in this topic

hey i just put in the jd jet kit in my 01yz426, i then went to a dry lake bed to toy with the jetting and the fuel screw. i heard after putting a jd kit in that my bike would snap up in 4th gear and be rediculously responsive...i do notice a little more responsiveness, but nothing major like i expected, can someone help me out as to what size jets i should use and how many turns on the fuel screw i should do. also if i need a different pilot, or leak jet? im riding generally at 2500 ft. nothing high, till i go to mammoth....thanks

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If the bike was already jetted near perfect, than the j/d will help a little but not a lot. It tends to help those the most who's jetting was off a bit.

Anyway, it's still a very good kit, and I recommend the (j/d) factory settings for your altitude/temperature.

I think my 2004 yz450f requires the 170 main jet from Sea-level to 4000 ft. and the blue needle set at the 4th clip position. (over 70 degrees and/or high humidity, switch to the red needle)

As far as the fuel screw goes, make sure the bike is fully warmed up. Turn the IDLE screw in to acheive a higher than normal idle. Then turn the fuel screw in

and the bike will begin to drop in R.P.M. until it nearly dies. (Don't turn the fuel screw in too tight or you will crush the tiny tip, just kiss the stop) Slowly back out the fuel screw until you reach the highest R.P.M. .....than stop. At this point you will be at about a perfect setting. From this position, try going in a 1/8 of a turn or out a 1/8th of a turn.....I find the optimum setting will make the bike backfire OCCASIONALLY, when the throttle is shut down. You don't want constant backfiring , but just a little occasional "pop". When you think it's just right, remember to reset the idle to normal....Hope this helps.

:excuseme:

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alright, thanks. also do you know if all the jet kits give the same results if the same jets are used (isnt a jet a jet no matter whos name is on it??), basically what im saying is: Will a fmf power up jet kit serve the same purpose as the jd or other brands? or is one specific for a certain application?(i realize the jd is more versital with more jets and needles but..money talks) thanks

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If the bike was already jetted near perfect, than the j/d will help a little but not a lot. It tends to help those the most who's jetting was off a bit.

Anyway, it's still a very good kit, and I recommend the (j/d) factory settings for your altitude/temperature.

I think my 2004 yz450f requires the 170 main jet from Sea-level to 4000 ft. and the blue needle set at the 4th clip position. (over 70 degrees and/or high humidity, switch to the red needle)

As far as the fuel screw goes, make sure the bike is fully warmed up. Turn the IDLE screw in to acheive a higher than normal idle. Then turn the fuel screw in

and the bike will begin to drop in R.P.M. until it nearly dies. (Don't turn the fuel screw in too tight or you will crush the tiny tip, just kiss the stop) Slowly back out the fuel screw until you reach the highest R.P.M. .....than stop. At this point you will be at about a perfect setting. From this position, try going in a 1/8 of a turn or out a 1/8th of a turn.....I find the optimum setting will make the bike backfire OCCASIONALLY, when the throttle is shut down. You don't want constant backfiring , but just a little occasional "pop". When you think it's just right, remember to reset the idle to normal....Hope this helps.

:excuseme:

hey thanks for the input,i will definently print this out and try it, but as far as the 170 jet in your 450,i think your carb is a bit larger than mine, but im not certain... i will test it out though, thanks again. oh and my bike i dont think was jetted that great before i did the mod, it started great but there is just that gosh dang bog when you snap the throttle back fast, i hate that...

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alright, thanks. also do you know if all the jet kits give the same results if the same jets are used (isnt a jet a jet no matter whos name is on it??), basically what im saying is: Will a fmf power up jet kit serve the same purpose as the jd or other brands? or is one specific for a certain application?(i realize the jd is more versital with more jets and needles but..money talks) thanks

Jets are standard regardless of kit unless they are custom drilled, but JD includes custom needles they cant be obtained elsewhere. I just received his kit Friday, I will have it in the bike in a few days. I will be running the Red needle and probably a 170 main. I actually run the 170 already. The needle and his mod to the accel pump will be done, though the BK/GB mod was done years ago. I also have been running the needle from an 01 for a while too.

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hey thanks for the input,i will definently print this out and try it, but as far as the 170 jet in your 450,i think your carb is a bit larger than mine, but im not certain... i will test it out though, thanks again. oh and my bike i dont think was jetted that great before i did the mod, it started great but there is just that gosh dang bog when you snap the throttle back fast, i hate that...

Remember, with these bikes you can't crack the throttle like a 2 stroker. You have to role the throttle. I have a yz400 and I have no bog at all since I learned this trick. Just mt 2 cents :excuseme:

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There have been a few individuals who have gotten rid of the bog entirely....but, it usually takes some time to customize the AP squirt amount/duration. My bike only has a tiny, tiny amount of bog, so I don't worry about it.

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If the bog is only on the stand dont sweat it. If it is under load then keep tinkering. I am just trying to obtain perfection for this moment in time and weather. :excuseme:

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I just put the JD needle and jet (165 instead of the 170 recommended) and my mid throttle bog is GONE and no more fouled plugs! :busted: I am a very happy customer!! :bonk:

:excuseme:

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