WR426 jetting question

hey guys

ok i need to change something because i am not getting the right response from the throttle. ok when i open the throttle fast to accelerate out of a turn it hesitates for a split second then comes the full power and its unpredictable. it goes from bad to worse as the life of the spark plug goes on. after i change the spark plug its fine but after about the 4th or 5th ride i have to change the plug again to get good response. also as the life of the spark plug goes on after i crank it and just wamr it up, it starts misfire here and there and back fires when i get on the throttle and let off real fast. i am in florida so 0 sea level. my mods r listed on the bottom. hope someone can help me with what jets to get and replace. thanks guys!


Look into the JD kit. I believe that it made a difference with my bike for the better. Also, it would be helpful to understand the throttle position your having trobule. When you snap the throttle open out of a turn it's not the same a snapping the throttle open from a stopped idle. You are probably dealing with 1/2 - 3/4 throttle issues, rather than 0 - 1/4 throttle (assuming your not a slow poke like me :thumbsup:).

Use OBELN-3(YZ250f Option needle), 160 main, 162 main air, 40 pilot, 75 pilot air, with an home made power now valve. Do the BK mod and adjust to 1 second squirt. Do a search on the JamesNow and BK Mods.

First get your jetting right, then you may want to consider the PowerNow or make your own version. Works great on my bike (02'wr426). Good luck.


thanks guys! i'll have to try one of the kits. how much do those usually cost?


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