fmf powercore IV vs. white brothers e series

Hey fellow thumpers, I have a 98' model that I am currently running a fmf powercore 4 on with a stock header and a 14/51 sprocket combo, to me (at 160) this thing hooks up out of the corners. hits hard on the bottom, My friend has a 01 that he just installed the white brothers e series pipe with stock header and stock gearing, and he installed all the plates on it. His hits twice as hard than mine does, couldn't keep the front end down!!! what are some of your likes and dislikes on these two pipes? any type of input would be great, cause I might be looking to change mine out!!! thanks

One thing to note, the "hit" difference between your 98 and the 01 might be the titanium valves train. I have a buddy who has an 00 426 (for sale) that doesn't have near the hit as my 01.

The one thing I don't like about my E Series is that it's too damned loud. I was checked at 105-107db at 20" That's LOUD! I got tired of listening to it after 5 straight days. Otherwise, it's a top-shelf unit and I have zero complaints.


I had a '99 YZ400 with a FMF powercore on it. It was not a powercore IV (maybe a II but I forget) and I also had a e-series with 12 discs on it, here is what I found.

Without any other modifications here are the differences:

FMF Powercore - Gives more top end.

E-Series - Way more low and mid but signs off early.

Both were used with the stock header.

And the '01 (my current bike) does hit harder than my '99 did.

I don't think anything but a titanium valve train and 26 more cc's is going to get you the hit of a '01 426.

I have a FMF powerbomb header with a stock silencer on my 426 right now, and the powerbomb header did seem to give it more top and rev over stock.

Wasn't there a difference in the ignition timing (mapping?) between the years? I'm sure that this may also have something to do with it. I would think more than the difference in headder pipes.

well would a header pipe get the "hit" on mine to feel closer to a 01 model? I just thought the header pipe at $200 was just a waste of money, how much difference do they make? thanks for the input, I always thought the fmf was more for bottom end power, go figure!!!

Thanks people, I guess I just need to buy a new model 426!!!! Make my wife proud, lol. thanks for the input on the subject!!!

Originally posted by m2g4b:

Make my wife proud, lol.

What's a wife? (LOL!) :)

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now