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Yzf_Buz

01 426 power now valve ?

7 posts in this topic

Over the winter I picked up a '01 426 in a trade and am new to thumpers and am just about to go ride it and have found a power now valve for $40 is this thing really worth putting in my bike? I will be riding mainly woods and trails not really a track guy but you never know. I am stoked to have a new woods weapon

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I have a 2001 426 with a power now valve and it works great for trail riding. $40.00 is a great deal. You should also do the 420 accelerator pump upgrade and install a zip tie adjustable air fuel mixture screw. These things will all help get rid of the 426 bog.

Brandon

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You should also do the 420 accelerator pump upgrade and install a zip tie adjustable air fuel mixture screw. These things will all help get rid of the 426 bog.

Brandon

Any info on this "420 accelerator pump ugrade". Or is this the same as the "AP mod" described here at TT?

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Any info on this "420 accelerator pump ugrade". Or is this the same as the "AP mod" described here at TT?

There are different AP modifications for different models, and the 426 and 450's that have bog issues have them for different reasons. The O-ring mod, etc., don't apply to the 426.

The BK mod does, however, and is said to help a lot. There's a link in the Common Threads sticky under Fuel System.

As far as the Power Now device on a 426, it's a waste of money, IMO. The intent of the device is to improve poor throttle response at low speed in engines with very large carbs and aggressive valve timing. They do help the low speed performance of a 250F noticeably, but the 426 can be "cured" without the expense, and really does not benefit much from it.

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I have the Power Now and it improved my throttle response from closed to 1/2 open. I have a '00 426. That and the Factory R&D P-38 Accelerator Pump Cover (Boyeson sells them too), really cleaned up that Yamabog the earlier models have.

You can make a Power Now yourself, search TT for the Free Power Now. All you need is an aluminum can, a small file and some epoxy. You can actually make one much better than the commercial one, you can make yours with much tighter tolerances to the slide.

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