Where is this BK Mod Info for 00 426

9 replies to this topic
  • John_Lorenz

Posted February 20, 2002 - 09:56 AM


I have searched the world over

Where can i find the BK MOD

[ February 20, 2002: Message edited

Never Mind I got Admin Pleas edelete this by: EgoAhole ]

[ February 20, 2002: Message edited by: EgoAhole ]

  • 98yz

Posted February 20, 2002 - 10:54 PM


Well one of a couple of ways.
1. Goto the search page and type "BK MOD" and hit the search button.
2. Goto www.mx393.cjb.net for pictures and write up.

  • therapture

Posted February 20, 2002 - 12:04 PM


Originally posted by 98yz:
Well one of a couple of ways.
1. Goto the search page and type "BK MOD" and hit the search button.
2. Goto www.mx393.cjb.net for pictures and write up.

Some people just refuse to use the tools right in front of them... :)

For example, the "bk mod" string returns about 25 hits easily on this forum....more actually, because the search engine limits the results to a set amount :D

  • motoman393

Posted February 20, 2002 - 12:21 PM


LOL...hey you were a TTalk newbie once too! Everyone has to learn about the search function sometime.... Later,



  • 98yz

Posted February 20, 2002 - 12:43 PM


I am gonna add the BK Mod to my 01 426 tomorrow night. I hope that it is everything that you guys claim it is. Thanks for all the post that you guys have put on here, I have solved serval questions now due to the information passed around on here (mainly that annoying backfire upon dropping off the throttle). I am pretty sure mine will benifit from the Mod greatly, if you stab the throttle on mine I get the nice cloud of black out of the exhaust, so I am pretty sure mine is shooting a very healthy dose of fuel to the cylinder.

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Posted February 21, 2002 - 05:25 PM


Hey Motoman393,

I went to your website, to become familiar with the "BK Carb MOD" procedure, since I definitely need to employ it on my 2000 YZ426F. However, I'm unsure about your one PIC that shows the "pump timing screw" and "accel pump screw" labeled at the end of your "BK Carb Mod Info/Procedure" section of your website. I haven't taken my carbureator off yet, let alone analyzed the locality of these screws mentioned above. I just want to know, from you, that the information regarding the "installation of a new 4mm screw/spring combo" in this scenario, pertain to your description in the PIC called the "PUMP TIMING SCREW ?" Another words, this "PUMP TIMING SCREW" doesn't exist in my carb right now. It's this UNIQUE combination of the "4mm screw/pen spring" that you mentioned, that becomes this "PUMP TIMING SCREW".....RIGHT or NO ??? Fill me in, if you could. Thanks for the HELP !!

(Fellow Thumperer)

  • SealClubber

Posted February 21, 2002 - 05:37 PM


Yes. The top existing screw adjusts when the squirt starts in relation to the opening of the throttle valve plate. The bottom screw,(BK MOD) will adjust when the squirt stops. If you don't like the mod you can always remove the screw and it will be like nothing ever happened.

Just make sure you drill the hole at the correct angle. I ALMOST screwed that up. :)

  • leif

Posted February 21, 2002 - 05:43 PM


What do you mean the correct angle?

  • Fastest1

Posted February 21, 2002 - 08:15 PM


He means perpendicular to the casting. When you take your carb off it will be obvious. This mod does work very well on a 2000 426! It does not change the popping on deceleration, that is a lean condition in the idle circuit. This can be fixed by richening the fuel mixture screw and if that doesnt work you must go to a larger pilot screw. Cya

  • leif

Posted February 22, 2002 - 02:14 AM


I guess what I meant is, how can you drill it croocked? Just look at the rotation.

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