Leak jet vs. BK mod

7 replies to this topic
  • Goosedog

Posted December 17, 2006 - 06:20 PM


As I try to get an understanding of the YZ426 carburator's short-comings I've figured out the "too much squirt is the cause of your bog" theory but I'm still not clear on whether the leak jet can provide the same fix as the BK mod. I made the mistake of going in the wrong direction with a potential fix by adding the Quickshot AP cover and had negative results, therefor it's getting yanked off. The BK mod should help time the squirt, right...but what does adding a leak jet do, and wouldn't it be a simpler fix? Can someone explain this to me.

  • Baron Von Beard

Posted December 17, 2006 - 06:41 PM


The BK mod came about because originally the carbs didn't have leak jets. The leak jet is the cure, the BK mod was the temp. fix. If your carb still has a bowl without a leak jet, order one from JD jetting and say so long to the bog.

  • Fastest1

Posted December 17, 2006 - 07:05 PM


? I dont believe a leak jet is used til 03'. No leak jet came with my JD Jetting Kit! I run the BK/GB mod the Boyesen, but I had my bog cured before installing the cover. The mod mostly addressed 2000-2001 concerns.

  • Baron Von Beard

Posted December 17, 2006 - 07:26 PM


I should have been more clear. JD has an FCR float bowl with leak jet upgrade and from what I remember it's not to pricey. Certainly worth it for the older model bikes.

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  • Fastest1

Posted December 18, 2006 - 05:02 AM


I have never heard that one before. Dont have the problems anymore so I dont keep up as well as I used to.

  • skthom2320

Posted December 19, 2006 - 09:58 PM


LOL! It cracks me up that everyone automatically says to do the BK mod on all the 426's! That mod worked great for the '00 bikes. But by '02 Yamaha had it pretty well dialed.

Tweak your fuel screw and the AP screw to get things dialed. Don't bother with the BK mod until you do that.

Sorry, but I can't help but offer the contrarian view...

  • jbrooks26

Posted December 20, 2006 - 02:43 AM


BK mod on my 02 worked wonders. However, had a float bowl with leak jet been available when I did this I probably would have gone that route. Just my 2c.


  • Goosedog

Posted December 20, 2006 - 04:03 AM


Can a bowl w/ leak jet from an '03 not be used on my '02?

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