my 400ex vs buddies 400 ex

[jrdrag5475]

Hey guys just have a quick question
Drag racing my 01 400ex vs my buddies 03 400 ex that a pure stock with stock tires and 38 tooth rear gear
I have a 01 400 ex with a pro circuit T-4 silencer, wiseco piston, titanium valves and hole shot tires that are smaller then stock tires. i have a 39 tooth rear gear.
Dragracing them i come out of the hole and just walk all over them until i hit 5th and they hit 5th gear and they just come truckin right around me and keep pullin away while i hit the rev limiter sometimes. now because of my 39 tooth gear thats giving me better acceleration correct. So should i go to a 38 or 37 tooth rear gear to help my top end

Thanks

[Barrymaxx]

yes, or bigger back tires.

[81 clark racing]

if you want more top id run 16t front 38 rear and 22s in rear tires or just run what you have now but by putting bigger tires on it will give you more top end. ull loose a good amount of low end put ull pull away topend

[quader400]

putting smaller rears and bigger rear sprocket on your bike kills your topend. if you either went like one or two teeth less than stock in the rear you would kill them

[ilpadrino113]

I'd personally rather have better acceleration than more top end.

But i don't get a chance to top her out on the trails aorund me so it all depends on where yer ridin.

[BossmanEX]

With the mods that you have, you could get an aftermarket rev box. You would gain another 1000-1200 rpms on the top end and you wouldnt lose any of your bottom end pull.

[j450rking]

you should relly get a hot cam stage 2 that would boost your top end alot and that would be cheaper than getter new tires

[jrdrag5475]

alright well i will stick with the rear tires i have and maybe go to a 38 tooth gear and then show them what i got. whats that aftermarket rev box and where can i get that? Any websites?
Anyone ever seen any improvements with a K and N air filter?

Thanks

[Pipeless416]

Originally posted by jrdrag5475
alright well i will stick with the rear tires i have and maybe go to a 38 tooth gear and then show them what i got. whats that aftermarket rev box and where can i get that? Any websites?
Anyone ever seen any improvements with a K and N air filter?

Thanks

going back down to a 38 might not make a big enough difference. i would keep the setup you have with the tires and rear sprocket, but change the front to a 16 tooth. a k&n will increase your power a little bit, but it wont raise your rev limiter which is what you're hitting too early. you've got the power over him, but his is geared better for longer drags.

[krt400ex]

right now...you looking at the equivalent of runninga machine with a 4-5 tooth larger rear sprocket because your running 18's on the back...and that has the effect of adding 3-4 teeth to the rear sprocket...i would either put 20s back on the rear or go up 1 on the countershaft sprocket...(same effect of taking 3 1/2 teeth off the rear)

[northwest Texas]

You have reduced your final drive from 2.53 (stock gearing w/20" tires) to 2.89 which is a HUGE difference. Do you even use first gear? Your 5th gear is about the same as his 4th.

To get back to near stock w/18's a 15/34 will be 2.52. Or a 15/35 is 2.59, 15/36 = 2.67, 15/37 = 2.74, 15/38 = 2.81 just for references.

If you want to keep your 39, a 16/39 = 2.71 w/18's

Just FYI the 15/34 is the closest with the 18's you have to the stock 15/38 & 20's.

[jrdrag5475]

well thanks alot for all your guys help i will have to see what i want to do and figure it all out. Anyone know of any other good power adders that i could throw on this for a reasonable price?

[krt400ex]

throw in a hotcams stage 1 or 2 cam....that will add a very noticeable amount of power