By crapping out, do you mean sputtering or the bike actually nearly dies and stalls?
I think that you might be encountering a problem not associated to jetting...
My 01wr426 runs killer and I didn't do anything but remove the airbox cover, exhaust tip, machine down the throttle stop...
I run from sea level to 6000 ft.
The yz cam timing is a wash, I miss the bottom end bark...
I think I'll go back to wr cam timing.
Yes ! the bike sputters real bad and will not pick-up and keep pulling through the power-band.
I've had this bike apart more than I've been actually riding it.
I feel I've been trying just about every jetting combo that is possible and ended up taking it to the shop out of pure frustration to get the problem solved. Unfortunatly, they only have a small little lot to try and recreate the problem that I keep experiencing and were unable to experience it.
I know how awesome the blue machine really is but at this point I'm beginning to think that perhaps there may be an elecrtical glitch that happens occasionally to make my bike start crapping out as it comes into the mid-range about 1/4 to 3/4 throttle. If anyone has had any experience with this kind of trouble please let me know what to do next.
I have previous posts that may make this problem a little clearer with the backround info.
Thanx & Hope to hear something new.
you're counting the clips on the needle from the top down yes!
with the carb off & a twist of the throttle is the accelerator pump jet working?
it should squirt for three or four seconds.
What are your jet settings right now? I had the exact same problem and just kept bumping up the pilot and main until the sputter went away. I am now at a 172 main, 48 pilot and 1 1/2 turns out on the pilot fuel screw, middle position on the clip and it runs perfectly.
I haven't yet pulled the carb off to verify that,and will definately try it, but it seems I would be experiencing this problem throughout any throttle position if the accel pump were failing - Yes ? Correct on the needle clip positions.
I am now at #168
Clear and cool...45-50 degrees.5500 ft
Trail rides fine. Track riding is the problem even after the bike has warmed up thoroughly. Hard acceleration out of turns at 1/4 to 3/4 throttle is where it occurs.
I never had this kind of problem with my 99 400. It's still at stock settings and only slight hesitation when it's cold.
I'll stick with it. Pretty frustrating though.
Shot in the dark: have you checked out the float level/operation at all? I do know Clark has stressed float height/operation on this bike.
Check the easiest stuff first. Sometimes you'll nail it.
I don't know your specific circumstances but... Unless there was a serious problem don't screw with the jetting! Ride it for a long while. Learn the bike at different altitudes at different locations. Yes different locations occasionally my bike will run differently at different locations at approximately the same altitude. Is there a lot of water around, fog (denser air), hot, cold. Personally, I've found that almost every symptom is caused by something other than jetting.
1. Wet air filter
2. Dirty air filter
3. Air leaks
4. Air filter with to much oil in it
5. Not allowing your air filter to dry after oiling it
6. Old spark plug
7. Clogged accelerator pump!!!!!
8. Throttle stop removed and not trimmed to the appropriate length FOR YOUR BIKE! (I would not recommend using someone else's cut off length, do your own research...)
I found that if I could diagnose the problem with one of the above problems it could always be cured with a couple turns of the fuel screw.
Remember the WR has a fuel screw not an air screw. Adjust the fuel to match the problem i.e. Dirty or wet air filter, engine not getting enough air. Go in on the fuel screw, decrease the amount of gas. You want to attempt to equalize the air gas mixture. (most of the time anyway...)
I only attempted to change my jetting when I figured out how my individual bike ran and only in an effort to get more power.
JJ from WA - 99 WR; WR timed, EKN Needle, Scotts stabalizer, Scotts triple clamps, Pro-Tapers, Michelin S-12's, Terry Cable hot start, MSR Raptor clutch lever, Moose skid plate, Works frame guards, Acerbis Pro Rally guards, Renthal MD-soft grips, Factory Effex graphics, YZ IMS seat base, YZ Factory Effex seat foam and gripper seat cover, YZ rear fender
You need to be a member in order to leave a comment
Sign up for a new account in our community. It's easy!
Already have an account? Sign in here.