2008 YZ450F jetting?

lumpy790
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lumpy790
Edited Date/Time 1/27/2012 5:59pm
Have a Dr D full exhaust on the way and wondering what others have used for jetting when going from a stock restricted 08 exhaust to a better breathing pipe?
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kippy450
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kippy450 1/8/2012 7:35pm
1/8/2012 7:35pm
I have an 08 yz450f with a Yosh pipe on it. I went with the Pro Circuit jetting specs:

Pilot: 42
main: 160
needle: NFLP on the 5th clip..stock needle is NFLR
leak jet: 55

This setup gave me a TON of lowend grunt and mid that I was missing before. The leak jet change got rid of a lot of the pog problems. Also, I prefer the stock header to my aftermarket ones....the power aways seems stronger with the stock. I know a lot people say you have to change it out because its so much bigger...I totally disagree with them!

If you don't want to do the PC...Dr.D's websites says,
165 main, 45 pilot and the clip on the 4th position.

I know a lot of guys just went one higher on the main....play with it and see which one you like best...either one will be WAY better then the stock muffler!
lumpy790
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lumpy790 1/9/2012 7:26am
1/9/2012 7:26am
Thank you for posting what your running. Just trying to get into the ball park..could not get into the DR D - jetting section with Ipad.

Thats what I hear..the muffler change makes a huge difference in bottom/mid. Was pulling holeshots with it bone stock..cant wait to ride it with the exhaust!
kippy450
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kippy450 1/9/2012 2:47pm
1/9/2012 2:47pm Edited Date/Time 1/9/2012 2:48pm
you will love it...totally wakes the bike up! You may actually have to ride the thing a little different with all the power your goingt to gain. I had to respect it more!

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