Different rebuild

[quadmanw]

The 400s getting a port job and valve job with a wiseco 11:1 piston and half race gas half 93 pump. Uni filter, rev limiter, and a jetted 450 carb. Instead of a 416. The port job is supposed to be alot better than the bore. And i can get it cheaper (;

[chronicsmoke]

I'd say you're being over generous with the race fuel on an 11:1..

If you don't have an issue running race fuel, try and get the most out of it and run a 12:1

[quadmanw]

The race fuel will make it run smoother. It won't always run on it. And the 12:1 has to many problems.. like dragging it behind a truck to start it the first time

[B.C.#11TRX400EX]

Ya u dont need race gas for 11-1 comp but i guess if u want to pay for it watever, when I get 11-1 im using 93 octane like usuall to keep that cheap haha

[quadmanw]

Just to experiment. Give it a try

[ish416]

Save your money on the rev limiter and get a cam.

400EX heads actually flow really well. A port job isn't going to make anywhere near the difference a high-compression piston will make. There is no reason to get any porting other than a mild port job.

Dump your timing key as well, otherwise your engine will go kaput.

I would only recommend running a race gas mix when it is extremely hot out. Otherwise, you will be losing power. It absolutely will not make the engine run smoother or better in any way except under extreme conditions.

Higher octane doesn't equal more horsepower.

[chronicsmoke]

Originally posted by quadmanw
Just to experiment. Give it a try

A mix of 25% 110-75% 93 is what I'd do. I always have a few cans of race gas on hand and add a splash (more for piece of mind) to the 400 on days that I know I'm going to pound the living **** out of it. Probably not needed, but I'm used to factoring the cost of VP fuel anyway so I don't mind too much. All of my riding is done on private land and tracks anyway so almost 100% of the hours are "abusive".

[CJM]

1. Your gonna need a cam, the stock cam is just plain horrible.

2. I bet your bore is slightly wore out, have it checked before you even buy a piston. Me, Id do a 407 if I could do it all over again

3. cdi with a higher rev limit on a 400 is pointless, it wont give you an ounce of more power b/c peak hp/torque is around 6000rpm on these things

4. Port jobs really not needed but if you want to.

Telling ya, copy my setup and you will be SUPER happy.

[powerbomb400]

I run a 50% 110 leaded and 50% 93 w/no ethanol. The leaded fuel really don't add hp but it runs cooler and help lube some of the enternal parts. Honda recommends at least a 92 octane for the stock system. Up to the mid 1970's all fuel was leaded. They cannot legally recommend leaded fuel by Federal law. The leaded in the fuel also will keep the carbon deposits from building up which does affect engine performance.