Adjusting jets in 426

I got a new plug, cleaned my carb and checked for air leaks. So I narrowed my rough running bike's problems down to my jets and or needle must be out of whack. I'm at 4700 feet and I quite often ride higher. Anyone out there have an idea of what positions I should adjust them too and the best way going about doing it. I'm not the greatest mechanic, but I dont trust my mechanic here.

Any help would be greatly appreciated!!! :applause:

Does anyone at least have the stock jetting specs for a 01 426 YZF?

Hey Smiticus,

I can forward you the 426 Manual in PDF format which has the stock jetting applications for the bike on page 42. I just got done helping MotoX with the same issue and he lives in CT. I also have a jetting Excel spreadsheet that has a formula that help get you close if not right on for jetting. The stock jetting for the 426 is:

162 Main

42 Pilot

Fuel Screw 1 1/2 turns

My current setup is AZ (1200ft) and I have gone up to Verde Vally (Cottonwood Area) which is around 4000-4200 feet without any problems is:

Main 160

Pilot 42

I do have a White Bro. E-Series on it, and a Power Now, not that it made a difference in jetting... PM me your email and I will forward you the Jetting Spreadsheet and Manual if you would like...

Thanks Chills, I sure appreciate you doing that!! Nice to have guys around like you, by the way I enjoy your avatar!

No Problem Bud, that why there's TT. Gotta Love em...

BTW - Thx about the avitar... HEHE

I'm in Denver (5280') and can't remember exactly what I'm running, but after I moved here from Texas, a local dealer told me to run 158 main, stock pilot (42), and raise the clip one slot on the needle. This is probably just what I did. My bike runs very well here. It is an 01.

My main right now is at 160 and I'm gonna tear into it tommorow to find the needle and pilot, but would it be a bad idea to put everrything back to stock and start from there, or would I most likely be running a little rich?

Yah, your gonna be running fat of you do that...

Alrighty, I have a chat with the local Yamaha dealer in the morning and see what most of them are running, hopefully they'll be helpful enough. Thanks man!! BTW how are those spider grips treating ya?

OMG....You have no Idea, I wont buy any other type of grip, they ROCK !!

Do they last long or are they just more sticky? I go through grips like I do Toilet paper. Where can I get em'?

I'm at 4700 feet and I quite often ride higher. Anyone out there have an idea of what positions I should adjust them too and the best way going about doing it. I'm not the greatest mechanic, but I dont trust my mechanic here.

Any help would be greatly appreciated!!! :applause:

Hey, I don't trust my mechanic either...

I'm at 4,500 ft., but seldom go much higher. I no longer have my '01, but here is what I ran in it:

EKQ needle, 3rd clip (1.5 clips leaner than stock EJP, and 1 size leaner just off pilot)

160 main (stock is 162)

40 Pilot (stock 42)

Adjustable Pilot Air Jet (see below) set at about 85

stock Main Air Jet

You can probably live w/out the adjustable Pilot Air Jet, but it was only $20 or so and killed the surging and popping that running the 40 pilot w/ the stock 100 pilot air stock resulted in. Not a big thing.

You can also probably do w/out the optional needle, but it made a big difference to my bike.

I would also recommend doing the BK mod (do a search here for "BK mod"), for any 426, but particularly for one at elevation. I think I had my accelerator pump stroke cut in 1/3. This is typical for those that try it, the difference is huge.

Here are some part numbers:

Yamaha pn for the needle above:

5JG-14916-E1

Sudco PNs (2 needed) for the adjustable PAJ:

021-230 (air screw)

021-235 (spring)

Hope this helps!

Do they last long or are they just more sticky? I go through grips like I do Toilet paper. Where can I get em'?

To be honest, the Spider (Slim Line ???) I dont remember exactly, they are like SLR or SLT something to that effect. They dont last long at all, but, at the cost of my hands, I will replace grips anytime. They are a soft composite and obviously the softer grips wear faster, but like I said, at the cost of blisters and sore hands, I will replace them anytime. Matter of fact one of the only places that has them is 55 miles away, and YES, I drove the 55 miles one way just to get them. Everyone I have talked to who has tried them, whether it be ATV or MX rider loves thems....

Thanks for the info Hick on the specs, I need to adjust my needle, but I do have my main at 160 and pilot at 40, my needle though needs to be moved.

Chills I'll have to get some of those grips, they sound rather enticing.

Thanks again guys, everything is extremely appreciated!!!!!

I've had jetting issue in the past with my '02 426 fouling plugs. Turns out to be more relate to the crappy winter gas sold here. Im at 4500ft and I run stock Main (162) and Pilot (42) but 3rd clip down on the needle. Stock is 4th. Now my bike runs great, its starts one kick, like turning on a switch.

I'm in Denver as well, riding an 02 426. I rode up Redcone pass (the top is 12000) and spent most of the time stalling and then kick starting forever :applause: . I have the gearing at 14/51 and it seems either my jetting is off or my clutch is having problems...Anyone have any ideas?

What's your main, pilot and needle position at? That's a ways up there!

Yes and at that elevation I was just dying trying to kick that thing over...I just got the bike so I'm not sure what the settings are :applause:. I will take out my plug and see if it is black how else would I tell?

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