How much Gain??

[04EX]

I have an 04 400ex with whitebrothers e-series. I was wondering if i would see any gains or how much gains i would see by
1.Removing Spark Arestor
2.Removing Air box lid
3.Jets

I was also wondering if removing the sparkarrestor or adding or removing the plates would be more effective.

[AtvMxRider]

You won't see any gains by removing the spark arrestor you may even lose power. You will see a little bit of gain by removing the lid . When you remove the lid you will probably have to rejet anyway

[AtvMxRider]

removing the plates around is just going to put the power in different places. Like more low end or more high end. Depends on what you want to do.

[04EX]

Ok so what number of plates will give me more top end or bottom end? like more plates for top end and less for bottom or what?

[AtvMxRider]

Honestly it has been so long I have forgotten. I think the more disks the more bottom end, I think. I had 12 disks in mine with a K&N and an open air box and it did great.

[JOEX]

Originally posted by AtvMxRider
Honestly it has been so long I have forgotten. I think the more disks the more bottom end, I think. I had 12 disks in mine with a K&N and an open air box and it did great.
It's the other way, more discs more top.

I used to run 4-6 discs at the dunes just to quiet it down some. There was some loss but not much IMO.

[AtvMxRider]

Originally posted by JOEX
It's the other way, more discs more top.

I used to run 4-6 discs at the dunes just to quiet it down some. There was some loss but not much IMO.


Told ya it's been awhile:D

[04EX]

So say took off the air lid and jetted is that a pretty noticable difference? cause right now i have stock jetting. with my white bro e series and uni filter.

i did all that to mine n it beats a near stock rapter n a drag. n taking the spark arrestor would give u more top end n a little less botom.

[AtvMxRider]

Originally posted by blue450yo
i did all that to mine n it beats a near stock rapter n a drag. n taking the spark arrestor would give u more top end n a little less botom.

[bwamos]

Originally posted by AtvMxRider


Well.. maybe it was a Raptor 350, or a Raptor 90. ;)


Back to the origional question.
Removing the Airbox lid, and rejetting will make a noticable difference. Not a HUGE difference.. but you will notice more throttle response, etc. It dies make a decent difference.

Exhaust Diverter plates:
More plates = more flow = high rev bias.
Less plates = more back pressure/velocity = low rev bias.

Very very basic description there.. but that's basically how you tune the plates.

[400EXBill]

You could try a 14 tooth front sprocket on it for more power too.

[04EX]

so if i go to a 14tooth front, you think i will notice it? I would imagine it would give me a little more off the line wheelie performance.

[AtvMxRider]

Originally posted by 04EX
so if i go to a 14tooth front, you think i will notice it? I would imagine it would give me a little more off the line wheelie performance.


It will give you a very noticable bottom end gain but you will loose some ontop.

[400EXBill]

You will actually only loose about 4 MPH in top speed according to this gear calculator.Click Here (http://www.fullthrottleassault.com/tech/gears/400ex.htm) Plus it's a cheap mod.