BK Mod Ride Report

5 replies to this topic
  • G-Man

Posted September 09, 2001 - 05:51 PM


Here's how my day went at SpeedWorld in sunny AZ. :) Started out at around 7am and the air was a "chilly" 78 deg to warm to around 95 deg.

I had changed the main to the 168, after doing a plug chop at my house yesterday, and the plug was greyish (with the stock 162).

Pilot Stock
Needle Stock and position
Fuel Screw 1.75 out
Stock Pipe
1.5 gal AV Gas to 3.5 gal Pump. (This works for me!)

Also of note is I have a spare set of wheels so I can keep some fresh rubber for race days. My practice wheel which I used, was considerably worn after approx. 15-20 rides.

The bike ran real good and there was never any hesitation, not that the 01 ever did. But now you could really grab a handful and the bike would go, and pull long with the larger main jet. Honestly I had expected more, but contributed it to the bald rear tire.

After confirming with my bud Kelly Bird (former Pro RoadRacer who held the #1 plate in AZ for a number of yrs, and toured the national circuit also. And can haul the mail on a dirtbike too!) about the 162 main being grey. He said not to worry about it so I decided to put the 162 back in to see if it made a difference.

WOW!!! That was it, now when you idle, you can just grap a BIG handful and instead of it flooding with fuel (before MOD), this baby RAAAAAPS like a dragster!!! On the track it definately was snappier, and seemed like it wanted to be in a higher gear, I can't wait to try it with some good rubber.

Now for the all important question, Kelly said it's ok to have a 4-stroke with a greyish plug and he even looks at the exhaust tip to get a reading, mine was still darkgrey/black. This goes against my 2-smoke days when a tan plug was considered ideal.

btw I was able to keep Kelly behind me for our last moto dice, something I have never done before for very long, and he said he could tell my bike was accelerating much harder and sounded better then before the mod.

He wants to do it too, but he has a Hybred 98 400 in a 2000 frame. I thought I read where you can't do it on those. Anyone have a spare carb they want to sell?

Summary: The Mod is well worth it, and it really is easy to do. Thanks everyone for their help and to ThumperTalk for having a great forum, for great stuff like this! :D

MXJunkie was there with his new trick forks and Emig racing clamps, and they looked REAL TRICK! :D He's still new to this sport and was looking for riding tips. The best advise I could tell him was to try to ride MORE LAPS to get his endurance and conditioning up, and he did a lot better than before.

Moto to Live
Live to Moto



  • forloop

Posted September 10, 2001 - 04:53 AM


Good Info G-Man.

The 168 main jet has always bugged me. I run stock pilot, thrid clip, and a 158 main. I have not noticed any lean symptoms.

I can relate to the gear higher thing. I was using third in corners that I was using second in. In fact, a couple times I had to double check what gear I was in. I could not believe third was pulling that hard.

I noticed that the bike even sounds different now.

01 YZ426F #85 Vet C

[This message has been edited by forloop (edited September 10, 2001).]

  • flyinguitars

Posted September 10, 2001 - 07:12 AM


I rode yesterday (first time since the mod). I noticed a little improvement but I think I have to check the squirt timing again. I left the stock main and went 1 3/4 out on the mixture screw. Since doing the mod I have noticed that if I whack the throttle while at idle, the bike stalls. I never really noticed this before as I would always roll the throttle on. This happens with and without the BK mod. I would like to cure this without cranking up the idle if possible. Any ideas? Thanks,

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  • YZThump

Posted September 10, 2001 - 01:22 PM


Hey G-man,sounds like you have it working pretty good!!! Have you tried a 165 MJ?I noticed a bigg difference with the 165 in that it kinda fell flat at high RPMs with the stock 162 and gives me a little piece of mind on the rich side!I have heard that the whitish plug is a 4-stroke trait!!

  • G-Man

Posted September 10, 2001 - 03:12 PM


Originally posted by YZThump:
Hey G-man,sounds like you have it working pretty good!!! Have you tried a 165 MJ?I noticed a bigg difference with the 165 in that it kinda fell flat at high RPMs with the stock 162 and gives me a little piece of mind on the rich side!I have heard that the whitish plug is a 4-stroke trait!!

Hmmmm that sounds interesting, might havta try the 165. I noticed the same thing, it wanted me to shift up more, then with the 168.

Flyinguitars, yea my idle is up a bit, but I like it as it helps in preventing stalling. I have no hesitation at all.

I hope this is true about the grey/white-ish plug.

Moto to Live
Live to Moto



  • motoman393

Posted September 10, 2001 - 03:53 PM


Thats cool G-Man that it works good for you!

When I did the BK Mod I noticed it didnt have the top end that is had before the BK mod! Like it wanted to be up shifted sooner (falling flat)! But now with the 168 it feels great! I am a "revver" not a "lugger", I normally bounce off the rev limiter constantly in 3rd gear instead of half way up in 4th (I stay in 3rd and never shift I just lug in berms and rev on straights/jumps). I havent track tested the 168 yet but in the 11 acre field behind my house it ran great. I may order a 165 to adjust it more. Im sure I will need the 168 anyway (since winter is coming up) Later,


I get my kicks on a 426!
Motoman393's MX Site

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