Bk MOD or JD Jetting?

I would like to do the BK mod but I have been reading that some people have opt'ed to do just the JD jetting. Should these be mutually exclusive?


These are for 2 different issues - What year bike do you have?

Bk Mod will only work on or pre 2002 426/400 - used to cure bog at throttle opening

the JD Jet kit for these bikes will add crisper jetting and more throttle response/better power

I have a 2000 yz426f.

I have the JD jet kit. It is money well spent. :excuseme:

I too have a 2000 426, I ran the BK mod for years and it is a great mod, the price is almost nothing but a little time. It does help a lot for starting/flooding issues. I also ran a needle from a 2001 YZF that helped also. Then I installed the JD Kit last week, I was already running the same main (170) and the same pilot (42) as he suggests for my altitude/temp. The needle (red) on the 4th groove (same groove I ran on my two previous needles) and then he says to install this oring on the adjuster screw and across the pump linkage ( I would have never thought it would do anything). The response now is F^&*ing incredible on a bike I already thought was running great. It always pays to tinker and pursue a finer tune. You wont go wrong with the JD kit and I dont think the BK/GB Mod is needed after the kit is installed. I have told all of my friends about the impressive results, I will be doing quite a few kits in the next month or so on mostly CRF's, so we will see if it is consistent. BTW it started the first kick and there is a noticeable difference in its tone. I just cant explain the difference in sound but if you heard it you would know it is on the money! It BARKS! It would be the first mod I would suggest to anyone seeking great performance. :excuseme:

the BK mod is only good on the 99-02 4xx bikes. after that you use different size leak jets in the bowl to do the same thing.

but do the BK and the JD jet kit

I think the oring does the same thing as the BK Mod, you also have to measure the gap in the accel pump linkage. I returned my Bk back to stock once I installed the JD kit and I mean it is crisp.

Thanks for the help. I think I will just do the JD jetting. Sounds like it will be more of what I am after.


How do you like the Rekluse on your 426? How does it do on the track?


Thanks for the help. I think I will just do the JD jetting. Sounds like it will be more of what I am after.


How do you like the Rekluse on your 426? How does it do on the track?


It is the best thing you could ever add to a motorcycle. The craftsmanship in spectacular, no stock parts need to be modified so returning to stock is simple if you dont like it. The negatives are that you cant push start it and at times when you are doing a jump immediately after a slow turn I cant clutch it because I dont run the override (though I do have it). I also run the left hand rear brake and I still cant stop feathering (subconciously still think it is a clutch lever) it during shifts, it just settles the front end when I do it not a screaming stop or anything. It will spin the tire always, wheelie when you want, basically it runs just like your clutch bikes do once the clutch is let out. But you can stop with no risk of stalling ever even after a crash it lays there running. It will also roll backwards down a hill should you kill it somehow (dont know how you would but someone has).

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