'01 wr426 missing at high rpms

sfc crash

Human Blowtorch
Joined
Jun 26, 2001
Messages
1,828
Likes
0
#1
it seems to be missing at high rpms and when i let off the throttle it backfires a little, seems to run strong tho as the "missing" is minimal , i think it missing. i've got less than 100 miles on it, removed exhaust tip, opened up the air box, cut the grey wire.? i think it might be jetted a little rich, but i am going to go to the yz timing, so i didn't want to mess with the jetting yet.:think
 
Joined
Jun 8, 2000
Messages
136
Likes
0
#3
It all depends on what needle your going to after timing change. If your going to DVP then you can bump up your main and pilot. If your going to EKP then your main is fine and bump up your pilot.
 

sfc crash

Human Blowtorch
Joined
Jun 26, 2001
Messages
1,828
Likes
0
#4
going back to work:( but i think mon or tues night i'll do the timing change, then i'll look into the jets, thumpertalk has some set ups for yz timed bikes, maybe get a new pipe too, but not as soon.thanks for the input, now it time to tear into the BRAND NEW BIKE:eek: ha!
 

wayneo426

Sponsoring Member
Joined
Dec 30, 2000
Messages
809
Likes
0
Location
Sandbar, NY
#5
Throttle stop?

SFC,
The culprit may be a missing throttle stop screw. Many dealers take the easy way out when delivering the WR new. Did they ask you if you wanted the throttle stop removed? If they did, and did NOT shorten it and REPLACE it, you very well may be confusing the TPS at WFO throttle. This will cause the bike to spit, and sputter @ high revs. I had the same issue resolved by cutting the stop down to a total of 23mm. The bike does not spit anymore WFO. There is an article on TT, here it is:
Throttle restrictor
Most dealers simply remove the stop. The ones that know what they're doing, shorten and replace it. The bike simply revs to the moon with it reinstalled at 23mm. If after all this, your still missing, I would re-jet. I have heard you dont have to re-jet when going to YZ timing. The jury is still out on that one.
 

wayneo426

Sponsoring Member
Joined
Dec 30, 2000
Messages
809
Likes
0
Location
Sandbar, NY
#7
Rev limiter

Kramer,
The missing from hitting the rev-limiter is not as "obvious" as having the slide open too far and confusing the TPS. Even though both suck, I found the miss to be a bit more severe, and annoying from the stop not being installed. Just my .02, anyway.
 
Joined
Aug 27, 2000
Messages
23
Likes
0
#8
Hi Tree Clippler
What is a DVP,EKP ?.What kind of power I am going to have after I change the timing ? I am a cross-country man not mx.My stock 2000 wr400 has some
jetting problem.What about yours? and last,What is the Fix ?