Proof is in the Puuuuding

Probably thought this was something perverted huh?


About four weeks ago, I mentioned to my good buddy and fellow competitor

Cliff Piper who owns a local suspension shop here in Phoenix about the BK mod. His shop has flourished in the recent yrs (he's the local Race Tech rep) and purchased a Dyno about a yr ago.

He's also owned and wrenched on the YZF's since their inception in 98, so he knows his way around them pretty good.

Went out practicing at SpeedWorld Sat and Cliff was there with his Box Van and his usual Posse.

Asked him what he thought. He was impressed and said "I've already done it to about 12 bikes!)

At a recent race I had noticed a dyno chart on the scoreboard from Piper Performance that was titled "Accelerator Pump Mod". I asked him about it and he said it does EXACTLY what everyone said off the bottom to midrange there was a 3hp difference. Inquired him about his jetting and he set the squirt at 1 sec and left the jetting alone. So there you have it, there are always skeptics but it's hard to argue with a dyno graph.

I can honestly say the 5cents I paid for the screw was the best damn nickel I ever spent!

btw I asked him "where my CUT was" he chuckled....


[ November 19, 2001: Message edited by: G-Man ]


This has been my thinking all along. I did not think you needed to re-jet your bike when doing the BK mod. All that is needed is adjusting the pump correctly.

I must admit I tought 1 second would be too much. My feeling is you jet to compensate for the lack of a pump then your constant speed settings will be off. The pump only works under acceleration. Once your at a certain throttle opening the pump is no longer in use.

Maybe, I am missing something basic here. You all are welcome to enlighten me.

OK now I'm interested! :) you can't argue with the dyno! is a 2000 WR 400 a canidate for this mod? thanks


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