Fatty, Gnarly or SST on 250CR2001 ?

[yzf426]

Hello, are there riders around here who have experience with the FMF Fatty, Gnarly or SST pipes for the 250 CR 2001 ? I have the Gnarly on mine and love it but it trades a little bit of top end from stock, so I was wondering if one of the others would be better for motocross.

 

[CR Swade]

The loss in top-end may be due to the lean main jetting from the stocker. I run a Gnarly on mine, and experience a better top-end pull, but that is because I run richer main (430), which allows it to run out better.

The stocker is rich down low to transition, then too lean. As far as the differences between the pipes, Gnarly and Fatty are almost identical except for wall thickness.

 

[yzf426]

I run the following jetting : 25 pilot, S-7 nozzle, std needle 3rd clip, 410 main, and 1 1/2 on the air screw. This works fine, but I'm going to try the 430 main as you recommend.
Thanks.

 

[John.T]

I really love my SST!! It gave me power everywhere! Some say its all hype but ride it then say that! I gained power everywhere,


ps,If you choose to get the SST and want to sell the gnarly let me know, because I need a woods pipe:D

 

[scotts250]

Pipe

Re-jetting for the pipe you have can make the difference. I put a Gnarly (Burly) on my '94 and it didn't run as well as the stock pipe until I rejetted for the pipe then I got better bottom (which is what the pipe is supposed to do) and didn't notice much if any loss on the top.
Scott

 

[John.T]

Good point scott's! I felt my bike was performing bad with the SST then I rejetted it, and it made a world of a difference! The bike sounded way better when I jetted it properly too:D

 

[motometal]

In my opinion, the jetting thing is part of the "hype" of pipes...many bikes could benefit just from the jetting alone, and jetting requirement changes due to different pipes are exaggerated. After buying the pipe, the owner feels obligated to re-jet...wow what a difference when the jetting alone may have gained 75% of the difference.

 

[BSWIFT]

I agree and disagree Motometal. Proper jetting will let the motor develope the proper HP and torque. A pipe will enhance different areas of the power curve but will "usually" have a trade off. A pipe change will result in a jet change, just like humidity, temperature, and elevation will require different jetting. JMO

 

[yzf426]

The re-jetting you did for the pipe, was it mainly by richening the main jet (if it was already jetted well)?