Can someone explain what I need to look for to insure I dont damage my slide when making the BK mod???????? Thanks in advance for your help..

Guess the search mode is still not working...huh rwcfrank? The grey/gray wire, BK mod and throttle stop cut mod are just a click away, complete with dimensions and pictures. If you can't figure out how to search this forum, you might consider not doing any mods to the blue machine! The mods are a more complicated task than a search.

I hereby nominate Thunder for HALL MONITOR! Blue, take it easy on the new guys.

Frank, I'll be doing the BK mod to my bike next week. I'm next door in Santa Clara. I'll let you know when I'm done. If you want you can come over and take a look.


Mike in S.V.,

Is it true you will soon be in my neck of the woods hunting Moose...which is really just an excuse to drink with me, Mark Trip and Mike68?

Heres my notes: I posted this in September 3 days after I bought my 2001 WR426, I know how it is to be nervous about your scooter and I agree that the "old timers' should be easy on those of *us* new guys....this is a step by step..... hope it helps

I just finished the BK mod (actually did it @ 12AM this morning) and I wanted to share my notes with a few of you who may be a little sketchy about drilling and tapping your carb. This is the best mod I have done so far to improve the useability of this bike! and the total parts cost was around $13.00 and EVERYTHING can be purchased from Home Depot 24 hours a day! (in most areas) PLUS the coolest part is it takes less than an hour to do.

Heres what I did step by step:

1)Go to Home Depot (11:00 PM 2 miles from home) buy a 6/32 NC tap w/correct drill (7/64) for the job(they come together in a pack made by "Hanson" for $2.89), also had to ge tthe tap handle $3.89, A small pack of 1" 6/32 machine head screws for $1.49, also a small pack of #6 washers (they opnly had the jumbo pack) $2.00 and a package of "handyman" springs (same isle as the screws part # SP-9700 made by "Prime-Line") $3.00, All total I spent $18.00 but that was because they had a 2 can special on WD-40 in a big box at the checkout stand for $2.89, and i'm a sucker for specials like that. (Jam Home)

2) remove seat/gas tank

3) remove coil (makes it easier to get at the cables)

4) remove throttle cable cover and unhook throttle cables

5)pull the octopus out of its cage and disconnect fuel line

6)loosen screw and allen bolt front and rear of carb and remove carb out the left side of the bike by pulling backward on the airfilter side of the rubber boot.

7)look in through the rear of the carb and rotate the cable wheel and count 'one one thousand-two one thousand" etc...etc... till the gas stops squirting (if you are anything less than about 4-5 seconds you may very well be the first one ever) mine was a little more than 5 seconds!

8)drain the gas out of the carb or it will spill on your garage floor and stink when you work on it (just tilt it sideways over a can or something)

9) mark the spot where you will drill the hole with a pencil then center punch it lightly to guide the drill

10) tape of stuff rags into the front and rear of the carb to keep the drill shavings out of the critical areas

11) but a amall piece of wood or plastic to tape into place so you dont drill to far and damage the little accelerator pump arm, then DRILL THE HOLE.

12) tap the hole (use a little WD-40 to keep the hole nice and tight) then blow off the chips and crap (or use a paint brush if you dont have air)

13) take one of the springs and stretch it slightly till it measures roughly 3/4" (they are 1/2" out of the bag)then take one of the screws and put a #6 washer on it, then the spring, then another washer, and then put this setup into your nice new hole.

14)Set the gas tank back on the bike and hook the carb to the fuel line and fill the carb back up with gas

15)now go outside (gas will squirt) and rotate the throttle cable wheel again and count, then turn the screw in a little bit at a time till you get below one second total squirt duration (actually .3 to .5 sec's), also look at when the squirt happens...it aparently needs to happen just after the slide lifts out of the way, so I adjusted the timing screw to make it that way (didnt take much adjustment) then I checked and re-checked the squirt duration and timing, I also went back after about 10 squirts and filled the carb up again to make sure there was no "low fuel" error, and rechecked it again.

16)Inspect EVERYTHING and make sure no dirt, debris or kaka got into anything then put a small drop of locktite on the front of the screw so that it wont vibrate loose (or tighter) and put the carb back on the bike and buckle it all up (reverse the removal proceedure outlined above).

17) I had to go to bed (it was midnight) BUT I was up at 8:00 am and ready to try it out....OH MY GOD!!!!!!!!!!!! the bike started first kick with the choke, and I could immediately tell there was something WAYYYYYYYY better about it, after letting it warm up I took it for a spin around town (heheh mine is CA licensed) this is HUGE!!!!!!!! it has so much better throttle response and pulls so much harder through low to mid range that I am completely BLOWN AWAY!

YOU NEED TO DO THIS MOD, it will change the way you look at your bike, it is a MUST do mod.....thats all I can say.

I hope this helps the newer guys (like me) who are a little aprehensive about tearing into your machine, even if you are a little less than mechanically proficient this is a really easy mod to do, the hardest part of the whole thing is not squirting yourself in the eye with gas cause you looked into the wrong end! (heheheh joke)

....let me know how it go's!


hey, ive asked this question before and didn't get a response. How is it possible for the acc. pump to hit the slide when cracking the throttle open? The second the throttle is opened, the slide leaves its resting position. Ive played with mine and cannot get it to hit the slide. Just wondering....


I was up in Canada hunting Caribou in September. The I was in the tundra when the planes hit the WTC. Had a real fun time trying to get back. In hindsight I should have called you guys to come get me on your WR's when I was in Montreal. I'd love to go riding with you guys in the winter out there but doubt seriously I'll be able to make it this year. Any chance you're coming this way? I've got to get ready, going riding with Monty & friends up at Stoneyford today. Later.



If your fuel stream is NOT hitting the slide, you are fat (fat, dumb and happy :) .

This is referred to AP timing. Just be happy yours is good!! :D

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