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duzz10

Stock Jetting for a 2006 YZ450?

11 posts in this topic

Do you have a manual? It's all in there.

The '06 came with a 42 pilot, and usually a 165 main. The bike should have been delivered with a 160, 165, and 170 jet, with the 165 being most often installed at delivery. It has an NFPR needle set in the #4 spot

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and at stock setting the 42 pj is too lean....needs at least a 45 depending on your altitude

I found the NFLR needle works well on the 06(07/08 needle)

but this is just me and my humbling experience trying to find the jetting sweet spot on a 06:thumbsup:

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The reason I ask is I replaced my 07 exhaust with a 06 exhaust. I had no problems before. Now when you snap the throttle off idle the bike will hesitate or die. I am thinking the 06 specs would be a good point of reference to start tuning at. My bike is supposed to have a 160 main, 45 pilot, and NFLR#4.

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I am thinking the 06 specs would be a good point of reference to start tuning at.
Maybe, but I doubt it. The as-issued '06 stumbled fairly badly. My '06's stand at 45/165/NFPR-4, and seem to work really well. Both have DRD pipes, however.

Your original point about header diameter is flawed a little. The '06 may be smaller at the outlet to the mid pipe, but the '07, IIRC, is a stepped header, and behaves differently because of it. If you have the original header, you can use that with the '06 muffler if you swap the mid pipe seal (I think). Could be worth trying.

What will make the stumble go away for sure is having the Zip-Ty carb mod done. Otherwise, your best bet is to work on accelerator pump tuning, and be sure your expectations of how well the bike should respond to the throttle, especially in neutral, are realistic.

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the 160 sounds too lean ....try a 165/168/170

Another vote for the ZipTy Carb mod....no more bog

it is going to be trial and error with the 06 pipe.....

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Maybe, but I doubt it. The as-issued '06 stumbled fairly badly. My '06's stand at 45/165/NFPR-4, and seem to work really well. Both have DRD pipes, however.

Your original point about header diameter is flawed a little. The '06 may be smaller at the outlet to the mid pipe, but the '07, IIRC, is a stepped header, and behaves differently because of it. If you have the original header, you can use that with the '06 muffler if you swap the mid pipe seal (I think). Could be worth trying.

What will make the stumble go away for sure is having the Zip-Ty carb mod done. Otherwise, your best bet is to work on accelerator pump tuning, and be sure your expectations of how well the bike should respond to the throttle, especially in neutral, are realistic.

My original header is in bad shape. I did find a new 07 on ebay for $50.00 buy it now that I went ahead and got. I can sale the 06 later. I did this because I like the way my 07 runs with the stock pipe. It has a nice smooth power band.

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Well I put my old exhast on so I can ride tomorrow. The same thing is going on. It dies when I snap the throttle, and when I ride it down the street it has a hesitation every time I get on it. It has been fine since I have had it. I did clean my air filter and had my tank off when I put the 06 pipe on. I don't know if something got in the carb either from the air box or where I had the fuel line off. Any ideas on what to check.

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If you ran the bike within 4 hours of putting on a freshly oiled element, you may have a blob of filter oil stuck in the air jets in the front (air intake bell) of the carb.

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I pulled the carb off and went through the whole thing. It looked fine and I didn't see any thing in it. Cleaned every thing and blew it out, put it back on. Every thing fine now, must of been something in there. Who knows, the 06 exhaust might of been ok. It has already sold though and a new 07 is on it's way.

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You very often never do see what it is that you took out of the carb to get it to work. The tiniest thing in the wrong orifice can upset the works pretty badly.

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