My buddy has a stock 400ex, and it runs good. Damn good actually. He can run right with piped ex's and what not. But he's ready to mod.

So I got quite a few questions for you guys with 400exs. And if you could answer, it would be a huge help, and would be greatly appreciated.


What and where can I find a good full system exhaust(around $400-$500)???

What is the compression of the stock piston, and what compression can he run with just running 93octane gas(standard bore)???

I have found a Stage 2 Hot Cam for $119.99, is that a good deal(i know ebay has them for $100 but don't like buying from there)???

His clutch is just starting to slip, so he should he buy a clutch basket and pressure plate, or just get a clutch kit with the heavy duty springs??

Would a rev box(alba) really help this motor??

Those are the questions I got. Any help would be greatly appreciated. Thanks ahead of time.

Ken

 

i no that a good exhaust for and 400ex is white bros. E-series. and the clutch slipping will stop with new plates and springs and proper ajustment. a rev box is a good thing for motocross so you don't constenly hit the limter and you can hold the gear your in for around the berms. this is moslty what i no about your questions and i hope i helped.

 

Ken,

I have a 2001 Honda 400EX and love it. But I mostly ride my DS 650. This is my opinion on your questions below.

1) Exhaust: Ive had Big Gun, Yoshi and a few others, and I feel I like the LTE the best. Its dual and its quiet, USFS Approved and stamped spark arrestor, and tested 92-93 DB and the new pipe increases stock horsepower by 3-5hp. The new design will probably be around $550-580 dollars. You'll have to wait until the end of the month for that.

2) Piston: If you are gonna stick with the stock piston, stick with the octane they recommend. When you get up to 11.5:1 then you can run premium at 98. 13:1 at 110 octane.

3) I put Web Cams in both my quads and love the service and quality. A new cam from them is around $154.70. If you are gonna keep the stock piston, then I would recommend the Web 450/451 Grind. Good for all-around performance which increases mid and upper end power. Stock valve springs ok. Specifications: Lift = .350/.345, Duration = 256 Degrees.

4) Those Alba boxes are made by Procom. The Power curve was developed by Big Gun. There's somewhat of a legal thing going on now between Big Gun and Procom. That CDI is fine for a single curve CDI - In the Big Gun form is like $92 - increased horsepower and the rev limit. However the best CDI on the planet is the Vortex CDI with up to 10 power curves - They got curves for low end torque and trail riding, high end power for racing, Linear power or stock curves. All with different rev limits. Two of the the curves are switchable on the fly via a handle bar switch. Expensvie at $399, but good.

Hope that helps ...

 

hmf makes a good full sytem in the 430 range, the stock compression is 9.75(ish):1 and the most you can really go on pump gas is 10.8:1 For the plates, i suggest getting oem plates with a spring kit from any of the manufacturers. Yes, a rev box on a buil motor will help, if it has a stg2 cam or similar.(no sense in turning the revs if it has already made peak hp)

 

Thanks guys.

Any other opinions appreciated.

Hell, all opinions appreciated.

 

http://cgi.ebay.com/ebaymotors/ws/eB...category=43978

big gun is a very good full exaust!!!!!!!!!!!!!!!![img]i/expressions/face-icon-small-smile.gif[/img]

 

for all the lazy folks [img]i/expressions/face-icon-small-smile.gif[/img]

 

thanks again, do you think a alba slip on would be about the same as a dg full system???

 

dg has never known to make superperb exhaust products..

 

Exhaust: Sparks, CT, Graydon Proline, Hetrick, LRD. Any of the Power Pro megaphone copies. If you need a spark arrestor forget the above systems and call FST and have him do an entire matched engine/exhaust.

I now like the Hot cams stage 2 after being a Web fan for a long time.

Wiseco 10.8:1 run fine on pump premium.

250R plates/fibers in the ex's with heavy duty springs. Best to run Honda GN not HP

A rev box I feel is a must with any higher comp engine.

A port and polish is a must too.


There are very good engine builders in your area. TC, FST, Hetrick, FDO, GT Thunder and more. The proper combination of these parts along with the port and polish will return the biggest results. The 400ex likes packages not the best parts from 5 different vendors. If I were building a low compression [pump gas] bike with a spark arrestor I would call FST without question.