jetting a 01 yz426f

hi, i have a yz426f 2001 and it came with a pro circuit t-f full exhaust system, header and silencer. i took the carb apart and found that my main jet size is a 162 which i think is the stock size, i am wondering if anyone knows what size jet i should put in with a full exhaust system. the reason i am asking about rejetting is because my friend has the same bike, but everything is stock and his front end will pull up in 4th gear very easily and mine wont. also if i quickely crank the throttle it will bogg for a split second and then go fast, but my friends doesnt. please help. thanks.

In 2001, I did the BK mod to the carb and set it at .5 sec. (if you don't know what this is....search)

I ran a 168 main with aftermarket exhaust.

I step leaner on the needle.

42 pilot

I ran a 165 main. If your looking for awesome throttle response, then buy a JD Jet kit.

hi, i have a yz426f 2001 and it came with a pro circuit t-f full exhaust system, header and silencer. i took the carb apart and found that my main jet size is a 162 which i think is the stock size, i am wondering if anyone knows what size jet i should put in with a full exhaust system. the reason i am asking about rejetting is because my friend has the same bike, but everything is stock and his front end will pull up in 4th gear very easily and mine wont. also if i quickely crank the throttle it will bogg for a split second and then go fast, but my friends doesnt. please help. thanks.

I also ran the full T-4 on my 02 YZ426 and had very good results using a J.D. jetting kit. Here are the best settings I found with standard needles:

1000'-3500' in So. Cal.

Main: 165 for 80-100 degrees or 168 for 40-80 degrees

Pilot: 42

Needle: STOCK

Needle Position: 4TH

Fuel Screw: 1.5-1.75 turns out

Should you decide you want to try the JD Jet Kit, I sell you the complete kit in the original package with the instruction sheet and sticker for $35.00 shipped to your door. I purchased an 06 YZ250 in Dec. and I can't use it in my new bike. :thumbsup:

Enjoy your bike

hey, thanks for that offer, i currently don't have the cash right now, but if you are willing to wait till the beginning of next month when i get my pay check, ill have the money then if you still want to sell it or if you haven't sold it yet, and ill buy it from you, by the way which size main jet did u run with the JD kit? ill keep in touch. thanks man

hey, thanks for that offer, i currently don't have the cash right now, but if you are willing to wait till the beginning of next month when i get my pay check, ill have the money then if you still want to sell it or if you haven't sold it yet, and ill buy it from you, by the way which size main jet did u run with the JD kit? ill keep in touch. thanks man

Ranger18, Thanks for the interest, but I actually received a PayPal payment for the kit this morning. I used the same main (based on temp) as I posted earlier with the JD needle. You may also want to check into a fuel screw that you can adjust by hand, I was using a Scott's T-Handle.

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now