12 replies to this topic
  • elmo426yz

Posted April 23, 2002 - 05:40 AM


Hey guys I am going to Colorado in June, I have a 01 yz426 with FMF Q muff and the power bomb header, Does anyone have suggestions on jetting? Or should I just run what FMF suggests? I will be riding in the 7,000-10,000 feet area


  • Merfman

Posted April 23, 2002 - 07:39 AM


Same bike, ESeries exhaust, stock header and
I'm using 40P, 2C stock needle, 162M, fuel screw adjusted as needed, 7 discs.

This jetting is what works in COS, ~6K' ASL.
I also rode same jetting last year on the CO500 and went from 4500-13K feet. Granted at 13K it was a little rich and didn't wanna run, but it did run.


  • motousa

Posted April 23, 2002 - 06:15 PM


Running the same here, good luck. I think i might run a 160 main every now and then, depending on the weather in Spring here.It is late and i am getting tired, sorry...

[ April 23, 2002: Message edited by: motousa ]

  • 4:20six

Posted April 24, 2002 - 06:25 AM


I think I put a 162 main jet in. Other than that play with the pilot screw. I run at 5-6000 feet with no fouling, backfiring, or bog with this simple change, but I have heard others move their needle clip, and change their pilot jet. I have never needed to yet, but I may when I get more time to tinker. Hey Colorado riders, Let's all plan a ride. At least a unofficial TT race at Berthoud would be fun. We are camping in the Walden Dunes for Memorial Day, gonna be a blast.

Our crew:
Me...2002 YZF 426 stock (mods on the way)
Mega-man...2001 YZF minor mods
Totem Pole...2001 YZF tricked out
Patron...95 yz250 Completely custom w/motor worked
M-Dude...2002 CR250 stock

We all rip it up, others are welcome to join us.

  • Merfman

Posted April 24, 2002 - 06:49 AM


Berthoud's a long haul for a day ride, but I'd be up for it. Lemme know when.

I'm a B class enduro rider so I doubt I'll rip it up with ya, but I'm game.


  • Hokie

Posted April 24, 2002 - 06:52 AM


Originally posted by Merfman:

I'm a B class enduro rider so I doubt I'll rip it up with ya, but I'm game.


I smell sandbagging already.....

I'm in for a Berthoud day.

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  • Dodger

Posted April 24, 2002 - 07:04 AM


Hey Elmo;

Sounds like most of us are in the same ball park. Here is what works for me...

For riding around Boulder/Front Range, including the tracks at Berthoud and Erie, I run a 45PJ, 162 main, and adjust the pilot screw as needed. (Not sure what clip I'm on for the needle, I haven't needed to adjust it). For going up into the Mt's, I usually drop my main from 162 to a 160, and adjust PS from there as needed. I'f I'm spending most of the day higher than 10K, I usually drop my main down one more step to a 158. I guess luckly for me, my jetting is close enought that all I need to change out if my main.

My $.04,

Dodger :) :D

  • 4:20six

Posted April 24, 2002 - 07:27 AM


How about this sunday? I know I'll be there either way, it's only a twenty minute drive for me, so I go every chance I get. If I get done with class by 2 o clock, I'm going today!

  • Merfman

Posted April 24, 2002 - 08:52 AM


No can do for me this weekend. I'm taking the wife riding on Sunday. She's had a WR250F since last January and hasn't ridden it once. Hokie and I also checked each other's schedules a couple weeks ago... I'm booked solid until after 5/12

Hokie, how was the Nat HS?

BTW, it ain't sandbaggin', it's hedging my bets.


Posted April 24, 2002 - 09:39 PM


I'm running BK mod, 165 main, 45 pilot, needle and clip is stock. Before I did the mod I ran 160 main and 42 pilot. Most of my riding is at Berthoud and Milliken. This has worked well for me. A TT ride at Berthoud sounds great if they run the track counter clockwise. I like the flow of the track better that way.


  • Hokie

Posted April 24, 2002 - 09:59 PM


Originally posted by Merfman:

Hokie, how was the Nat HS?

BTW, it ain't sandbaggin', it's hedging my bets.

I missed the HS since I wadded myself up at Erie the Sat. before. I was practicing for the Sun race at Erie. Damn, I hate that place! :D

Screwed my knee up, pretty sure nothing permanent, it feels pretty good now. Getting it checked out next week though just in case. Got some Asterisk knee braces now, those things are SWEET!

I can not ride this weekend either, I'm leaving for New Orleans to go to Jazz Fest tomorrow night.

As far as hedging bets goes:

Don't believe a word he says!
I have seen those Enduro guys ride the track, they might not jump everything but they will catch up in the corners! :D

[ April 24, 2002: Message edited by: Hokie ]

  • motousa

Posted April 24, 2002 - 03:40 PM


I am all about a TT ride...anywhere, so we should get it done. I have had the Asterisk braces since the start of the season, I love them!

  • PumpkinHumper

Posted April 24, 2002 - 05:15 PM


Hey Elmo,
Good luck in Colorado. I made the treck from Michigan to Colorado last July. Had a blast. Had to go down a bit on the main and lowered the needle a notch or two but that was it. If you have never been there you will have a blast. There was still snow on some of the passes when we were there in July. June should be really interesting. Your 426 will feel like a 250 out there. I was shocked at how much power the altitude suckes out of these bikes. But on the pluss side I did get 90 miles out of the stock tank one day. I can hardly get half as far here in Mi.

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