jetting for 444cc motor

7 replies to this topic
  • Guest_BrandonV_*

Posted May 18, 2005 - 03:27 PM


I'm expecting my cylinder today and my head by the weekend so I can finally put this thing back together :)

I'm a little concerned about what to do about my jetting though for my 2000. I have FMF powerbomb header, FMF Q silencer (the old one) and the airbox lid removed w/ twin air filter. I've also put the OBEJP needle in and the optional AP diaphram from the 03 450.
I ride around 3-4k ft and temps around 70-80f. How much higher should I go than stock on the main and pj? I want to be on the rich side while breaking in.

Edit: I also have the 450 exh. cam.

Appreciate any knowledgable advice.

  • Fastest1

Posted May 18, 2005 - 08:50 PM


Did you try the jetting forum? I would think your last jetting would be a good start, then fatten it up.

  • Guest_BrandonV_*

Posted May 19, 2005 - 05:54 AM


Did you try the jetting forum? I would think your last jetting would be a good start, then fatten it up.

I've tried the jetting forum multiple times and cant even get a response.

Whats the stock jetting on the 450's?
Someone get me rich.... please! I mean the bike.

  • Dolce_Grappa

Posted May 19, 2005 - 02:04 PM


I think it's fair to say, nobody is responding since you've made so many changes to your motor. You don't need to rich for break-in, anyways it will be rich already. You need to decrease jet sizes w/bored cylinders. I would start at what your stock jetting is, and see how it runs. If it's hard to start adjust you fuel jet in, still hard, downsize your pilot, then work the needle, then the main.

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  • felony

Posted June 05, 2005 - 03:14 PM


i would try one size richer on the main and pilot for starters.expect more midrange torque with the 444 will be noticeable but not not you'll get 4 hp though

  • Hick

Posted June 05, 2005 - 11:12 PM


Hey, I had an overbore in my '00, and also ride at about 4,000 feet.

I did not change the jetting from the std. bore. aside from maybe some idle mix adjustments. My '00 and '01 were jetted as follows:

160 main
40 pilot
about 95 pilot air jet (back to stock 100 w/ the FMF Q though)
EKQ clip 3 (equivalent to EJQ 2.5, Q vs. P is one size leaner on straight)
stock MAJ

At least, that is what I have down, that was a long time ago.

I also ran an FMF Q on my (std. bore) '01 and it ran better w/ one size smaller pilot compared to stock.

All I changed on the motor when I bored it was the piston size, and I left the jetting alone.

Hope this helps.

  • Guest_BrandonV_*

Posted June 06, 2005 - 06:12 AM


That does help. Thank you!

I've been getting so much different jetting advice that its very confusing. One local (very reputable) engine builder told me I should be running between a 172 and 178 main for the high desert (3-5k ft) and multiple people have told to stay stock or go down even. This is a PIA.....

appreciate your input though Hick.

  • Hick

Posted June 06, 2005 - 08:29 AM


One local (very reputable) engine builder told me I should be running between a 172 and 178 main for the high desert (3-5k ft)


That's just such a completely backwards suggestion I'm not quite sure what to make of it.

Maybe the problem is that not too many folks really ride at elevation. That is where I live, and as a consequence I've had to rejet every bike I've owned. And every single one has been 2-4 sizes leaner, nearly everywhere. Figuring the needle is always the hardest, but also the most rewarding.

Hope you get it sorted to your satisfaction.

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