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Yamaha piped yfz, need help jetting..

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:bonk::bonk:

I have a 2006 yfz with the HMF bill Ballance Pro series pipe, K&N prodesign filter with the airbox lid off, Needle in third position from the top, 175 main jet ( tried a 165 also), fuel screw out 2.25 turns, a 48 pilot jet. After warm up bottom end is good, but mid is real boggy, and it shoots flames out the exhaust (with spark arrestor in) about 1 foot. any suggestions will help. Thanks

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go richer. since the needle cant be adjusted, its kind of a pain but you have to adjust the other jets around this problem. mine runs beautifully with a 205 main. but that is with the airbox eliminator kit.

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:bonk::bonk:

I have a 2006 yfz with the HMF bill Ballance Pro series pipe, K&N prodesign filter with the airbox lid off, Needle in third position from the top, 175 main jet ( tried a 165 also), fuel screw out 2.25 turns, a 48 pilot jet. After warm up bottom end is good, but mid is real boggy, and it shoots flames out the exhaust (with spark arrestor in) about 1 foot. any suggestions will help. Thanks

Can't you just get a needle from an 04, or 05 and use it??? :bonk:

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I have a adjustable dyno jet needle in there, its in the tird position from the top. still need help. Thanks Chad

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I have a Dyno Jet needle in there now, It's in the third position from the top. Still Need Help! Thanks FFChad

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have you taken out the main and pilot and made sure they were clear? I am running like the same jetting, but i haven't done anything to the needle yet and got same mods. Mine runs very good, except back fires on decel which can be an indication of the needle being a tad lean tho. Mine has no bog. I have the dr. d exhaust and they say to raise the needle all the way and I haven't touched the needle so it all makes sense. The needle needs to be richer (at least in my case). What does your plug look like? Lower the clip and see what it does. If you have sputtering on top try a 172 main.

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you need the 45 on pilot 165 tops on the main get the yzf bike needle on the third clip 2 turns out on the fuel air screw

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I have a adjustable dyno jet needle in there, its in the tird position from the top. still need help. Thanks Chad

I hate to say it but REMOVE the DJ stuff, get last years needle and 45~48 pilot, 165~175 mian. Get a Scotts "T" handle fuel screw and you are good to go.

Remove the airbox lid if possible.

Check the accelerator pump timing and spray length, adjust as needed.

Here is what I found:

http://hmfengineering.com/forums/showthread.php?t=1119&page=1&pp=10

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:bonk::bonk:

I have a 2006 yfz with the HMF bill Ballance Pro series pipe, K&N prodesign filter with the airbox lid off, Needle in third position from the top, 175 main jet ( tried a 165 also), fuel screw out 2.25 turns, a 48 pilot jet. After warm up bottom end is good, but mid is real boggy, and it shoots flames out the exhaust (with spark arrestor in) about 1 foot. any suggestions will help. Thanks

....175 is pretty high...168-172 is about all you need piped and air box lid removed.Ct racing sonic pipes are shipped with a 168.Toomey-ct racing-alba action..all of them suggest not jetting past 172.The other thing I noticed right off the bat with my `06 yfz is that it popped and backfired sometimes.Thats because it was sucking air thru the rubber intake boot.the clamps that hold the carb to the intake have bushings in them to prevent you from over-tightening them.The problem is that the bushings dont allow you to tighten the clamps enough to properly seal the boot.I took my clamps off and discarded the bushings,then re-installed the clamps...problem solved. :bonk:

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