I was thinking of getting the big bore 440 kit for my 400ex but you have to put a bigger sleeve in the cylinder for this. Another option is the 426 and just bore the cylinder to fit the piston. How much more power would the 440 have over the 426, is it worth the extra money. I wanna run 11:1 on either piston and run the 100 octane, since your running a bigger piston do you have to do any head work? Also what would be a good cam to run to gain more mid to top-end power?

 

The 440 kit is actually a 435 kit. So in my opinion and what I am going to do is go with the 426 kit. One, it is about $185 cheaper. Two, you cannot screw it up and put the sleeve in wrong and pop head gaskets. Three, when it wears out, then you can go to the 440 kit instead of replacing that part of the motor.

You shouldn't have to do any head work unless you want to. Be careful of which cam you go with, some you have to get hardfaced rockers $$$ some you don't.

Back to headwork, I port matched my exhaust and intake and it made a noticeable difference, other than that and a xr400 headgasket, my bike is stock and I can beat bikes with pipes.

I am going to try the stock xr 400 cam or the stock xr400 race cam, not sure which, but I like the idea of Honda reliability as opposed to aftermarket. I want to know what the difference is between the xr400 cam and the 400ex cam. I know it will drop in, but I would like some specs and/or dyno graphs. First, I need some new wheels and tires and +2 a arms to go with my works shocks. So I will let you know in about 6 months how the cam went.

 

I personally prefer the 426 kit, That is what I have done. A good cam is the 450/451 grind from webcam. If you contact them ask for Lauri dunlop. She will help you with any questions you may have. I had the valves 3 wayed and I cleaned up the casting marks and port matched the intake and exhaust. I put on the higher rev limiter, k&n air filter, and a Big gun exhaust system, and the cam. There was a very big gain in performance. Then I decided that since the savings I had from not going to the 440 kit, I put on an FCR 39mm carb. I then had another big gain in power. I would suggest that if you want more top end then go with a different pipe such as the DMC.
This set up has beat its share of banshees, DS650's, and 440ex's up sand mountain at the dunes of Utah.

'00 400ex
'99 426ex
'99 Banshee
'96 300ex

 

Actually 426 or 436 Go with the 426 and put the savings from the kit and additional machine work and buy a 450-451 grind cam. Put a revlimiter from a newer xr250 on it. Port match the intake and exhaust and get a free flowing exhaust. Get a FCR carb when you can, it helps alot on topend.

99 426ex , Web Cam, FCR carb w/ twist, CT revlimiter, DMC exhaust, XCT's ,K&N, One kit, Renthal bars, DG nerfs, PRM Baja bumper, Armidillo Swingarm plate, 8 paddle Haulers

http://www.trxoutlawz.com/

 

Hey, did you keep the stock headpipe? I noticed that there was a huge weld bead in my right side pipe that was taking up probably 1/5 of the opening. I bored (just cleaned up the weld) both of the header pipe intakes also along with the head. There you go, a free tip if yours has a problem. The other side had a bead, but it was not nearly as bad. hope it helps.

 

Do you need different valve springs with the 450-451 grind Web-Cam? Where do you notice the power gains with this cam? Do you think an even higher duration cam with the valve springs would help even more?

 

Do you know the web site address for webcam?

 

hey, y2k300ex, here is the address for webcam

http://www.webcaminc.com

Ask for Lauri...

 

Not to say which is better because I have not even seen much less rode a 426,but I do have a 440.It has the White Brothers all around cam,WB rev limiter,K&N power up kit,WB E-SERIES exhaust.I to have had my share of Banshees and 250R's in the woods.I have also not yet spent the extra $250 for the head work yet.So on the whole i guess you get what you pay for and in the end your dollar to horsepower ratio is going to be the same no matter what road you take.Just remember the old saying-THERE IS NO REPLACEMENT FOR DISPLACEMENT.

 

When you port-matched the exhaust side, did you take the head off and remove the valves with the exhaust bolted up?