Jetting.... finally got it right....

[AMA714]

As some of you may know, I built an A/F with a 2008 Gen4 CRF250R. At first I was running a stock PJ with Pro Circuit recommended jetting for my pipe. Bike ran good, started and idled, but plug was dark, and it just seemed real fat to me. I picked up a PWK and had to start over on all jets. Got it decent, but felt it was still off. I was using a 1369 Needle, 38 pilot 2-1/2 turns out on air screw, 160 main. I figured it was the Texas heat and the small airbox of the 08 CRF that was causing me to use somewhat thin jetting.

Just for fun I swapped in a DGN needle as Bob has suggested many times.....
All I can say...... I'm a fool for chasing everything and not trying this needle!!!

The bike is a changed machine!! I mean, its crisp, strong, clean and actually easier to ride! I could not be happier. Bottom end cleaned up, mid still pulls hard, and top end just rips!!! This thing is F'N FAST..

It might not be the ticket for everyone, but it sure fixed me up.
P.S. Tony, I ordered you a new DGN.. this one is staying in my bike...lol

[AlisoBob]

[redrocket190]

I'm having an ah-hah moment. Have the DGN in the PWK 39.5 and the bike pulls like a tractor. However it looks like I am too conservative on the pilot (50) and the main (170)...

[dannygraves]

my old completely stock gen-4 ran a pwk 39.5 on DGN needle 172 main, 45 pilot. all at about 2500ft

[AMA714]

I am bumping up to a 40 or 42 pilot now that the temps are below 80. The surprising thing to me is the 160 main... I still think the little 250F airbox limits flow. I have ported it with six 5/8" holes on each side of the airbox cover to get more air in.

I ride MX only, and at Cycle Ranch i am WFO 3rd and 4th quite a bit; so far so good! Plug color is just starting to get to a nice tan color