P-38 Mod ???

5 replies to this topic
  • critter

Posted November 30, 2002 - 10:34 AM


I was just on a sight that referenced the P-38 aftermarket part(???) and I did a search here for it with no luck. What the heck is it, according to the site it was referenced on it has the same effect as the BK mod. Help !!!

  • Hick

Posted November 30, 2002 - 01:00 PM



I just did a search for "P38" and got about 80 results, so you are doing something wrong.

Anyway the P 38 is just a replacement accelerator pump cover. It has a thicker bottom, and since the pump is spring operated and it continues to spray until the dimple on the pump diaphragm bottoms out on the inside of the pump cover the P38 results in a shortened accelerator pump stroke (and less fuel delivered) relative to stock.

The BK mod does the same thing for '00 and newer Yamaha Flat CR carbs for less money, and it is infinitely adjustable, where the P38 is not.

For older FCR carbs or all non-Yamaha applications you can buy a small wheel collar from a hobby shop to affix to the pump actuating rod outside of the carb body, the collar will bottom on the carb housing acting as a pump stop.

When you figure out the search function search for "wheel collar." :D

  • critter

Posted November 30, 2002 - 05:11 PM


Hick,P38 with no dash worked...Who makes this ? I'm looking for something bolt on versus the BK mod for simplicity sake. Do you know anyone using the Power Now on a WR or YZ 426 ???

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  • freestyle111

Posted November 30, 2002 - 05:21 PM


yes p38 is bolt on.installation is vary simple.it basically does same thing as bk mod.i have p38 on my bike after its installed you will have to rejet carb.it took me about a hour of experimenting with different jetting combination before i throttle response perfect.here is a pic of p38 installed Posted Image

  • Bill

Posted December 01, 2002 - 02:51 AM


Here ya go




Posted December 01, 2002 - 06:56 AM


Why did you have to re-jet? The p-38 I put on my YZ works great with zero jetting adjustments. I did the wheel colar mod on my WR and saved over sixty bucks...

Bonzai :)


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