jetting for 426-444, gremlins excersized!


6 replies to this topic
  • ToxicT

Posted May 08, 2007 - 05:56 AM

#1

starting break-in on new eric gorr 444 kit.
OK I live at 7400 ft in altitude on sugarloaf in boulder, co
3 years ago after getting the JD jet kit I figured out how to dial it in being mostly stock.
after start-up the pipe is glowing red.
switch to my 170 main and 142 pilot dropped the red needle to the 2nd clip.
(as rich as I can set it) and still glowing red.
today I'm going to find some bigger jets, and plan to soak it till I foul the plug and work leaner from there.
anybody have a base line for the big bore kit?

  • SXP

Posted May 08, 2007 - 06:35 AM

#2

starting break-in on new eric gorr 444 kit.
OK I live at 7400 ft in altitude on sugarloaf in boulder, co
3 years ago after getting the JD jet kit I figured out how to dial it in being mostly stock.
after start-up the pipe is glowing red.
switch to my 170 main and 142 pilot dropped the red needle to the 2nd clip.
(as rich as I can set it) and still glowing red.
today I'm going to find some bigger jets, and plan to soak it till I foul the plug and work leaner from there.
anybody have a base line for the big bore kit?


If you are using the glowing header as an indication of jetting, you are barking up the wrong tree my friend. While an overly lean mixture will exacerbate the problem I wouldn't hang my hat on the glowing header solely as an indication of poor jetting. The headers on any of my "perfectly" jetted WRs will start glowing red if left idling for more then a couple of minutes. This is completely normal and has been discussed on this and the YZ forums ad nauseam over the years.

Where have you been?:applause:

  • rheynard

Posted May 08, 2007 - 07:15 AM

#3

Yep I agree, the glowing red is normal. I learned this riding at night!!

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  • GCannon

Posted May 08, 2007 - 07:36 AM

#4

If you are using the glowing header as an indication of jetting, you are barking up the wrong tree my friend. While an overly lean mixture will exacerbate the problem I wouldn't hang my hat on the glowing header solely as an indication of poor jetting. The headers on any of my "perfectly" jetted WRs will start glowing red if left idling for more then a couple of minutes. This is completely normal and has been discussed on this and the YZ forums ad nauseam over the years.

Where have you been?:applause:



YEAH!!!!! :p :p :p :applause: :p :p

You should be reading the stickies At your altittude you start with Indy's jetting chart which he so painstakingly put together for your benifit the least you could do is read it and use that as a baseline. Then make corrections from there. I can't understand what overrich jetting is going to do for you.
You could also search high altittude jetting for more information.

  • jonova

Posted May 11, 2007 - 05:23 AM

#5

ToxicT,

I went through jetting issues when I went to the 444 size motor. Jetting after a big bore is counter intuitive. Your initial thought is that the motor needs more fuel because it is larger. Which is correct.

BUT!! The motor is larger and thus acts as a larger more efficient pump and pulls more fuel through the same size jets. So having said this, the jets you will use are actually going to be smaller than when you had 426cc.

I didn't change any jetting on my bike after the 444 kit and found that it wouldn't idle and would stall very easy. I thought this was a lean condition and when to a 48 pilot, things got worse. I then went to a 42 pilot and it was perfect. I played with the main jet for a while, doing some 4 gear high load runs and checking the plug. A 168 main gave me the best color and feel.

I ride at sea level and run a 168 main, and a 42 pilot with the clip in the middle.

When I had 426cc I ran a 172 main, and a 45 pilot with the clip in the middle.

Good luck with jetting, PM me if you have any questions. I know how frustrating jetting can be:foul:

Russ

  • Birdy426

Posted May 11, 2007 - 11:46 AM

#6

I ride at sea level and run a 168 main, and a 42 pilot with the clip in the middle.

Russ


That's exactly what I ended up with as well...plus JD Blue needle on the 2nd position from the top. I ride the so cal desert from anout 2k to 4k feet altitude.

  • TeamScream

Posted May 13, 2007 - 10:27 PM

#7

I agree with everything the other 2 guys said, I live at sea level and both mine and my wifes 444's are JD jetted and run bitchen.

Heres mine: Wifey's looks identical.

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