Building up a 400EX motor
#1
Building up a 400EX motor
Okay all. I've been out of racing for a couple of years now, but I'm planning on getting back in.[img]i/expressions/face-icon-small-happy.gif[/img] Also, before the season starts again, I want to build up my motor again. I have a few choices, but hopefully you all can help me out, and give some suggestions.
<u>416</u>
*87mm JE piston (? compression)
*Cylinder bore & hone
*Port & Flow head (w/3-angle valve job)
*Camshaft (drop-in or other?)
*FCR carb (? mm)
I've also thought about the following:
*Oversized valves
*Hard-faced rockers
*HD timing chain
*HD connecting rod
*Weld and true crank
*HD valve springs
I just feel confused on everything right now. Any info, help, or opinions you can offer about my potential setup would be greatly appreciated. Thank you.
<u>416</u>
*87mm JE piston (? compression)
*Cylinder bore & hone
*Port & Flow head (w/3-angle valve job)
*Camshaft (drop-in or other?)
*FCR carb (? mm)
I've also thought about the following:
*Oversized valves
*Hard-faced rockers
*HD timing chain
*HD connecting rod
*Weld and true crank
*HD valve springs
I just feel confused on everything right now. Any info, help, or opinions you can offer about my potential setup would be greatly appreciated. Thank you.
#3
Building up a 400EX motor
You got a nice list there. I would go with 11:1 comp. JE or Ross piston, and FCR 39. Porting will help a lot, the HRC cam is a drop in cam, made by Honda, gives awesome top end. I don't think you need a the HD stuff, but it woulndn't hurt. Also the Sparks X-6 is a great pipe.
#4
Building up a 400EX motor
Right now, my motor has the following:
*Stock bore, 11:1 Wiseco piston
*XR400 cam
*Sparks X-6 full system
*rejetted factory carb
I noticed a really nice gain in power over stock (obviously), but I'm needing more power.
Should I just go with an overbore (416cc) TRUE 11:1 piston, HRC camshaft, Port/Polish head (3-angle valve job?), and 39mm FCR carb? Or is there something I should change? What kind of rear wheel numbers are we looking at? Thanks.
*Stock bore, 11:1 Wiseco piston
*XR400 cam
*Sparks X-6 full system
*rejetted factory carb
I noticed a really nice gain in power over stock (obviously), but I'm needing more power.
Should I just go with an overbore (416cc) TRUE 11:1 piston, HRC camshaft, Port/Polish head (3-angle valve job?), and 39mm FCR carb? Or is there something I should change? What kind of rear wheel numbers are we looking at? Thanks.
#5
Building up a 400EX motor
I know, I know. I've got a Wiseco ![img]i/expressions/face-icon-small-happy.gif[/img] It's not terrible, but there is certainly better available! I was actually looking at a 12:1 or 13:1 JE or Ross piston, and a hotter cam. A better carb is in the cards too.
I still have a few questions. Should I overbore any? Also, where can I get these parts cheap? (You must remember I've been out of racing for a couple of years now.) Any help you guys can give is greatly appreciated.
I still have a few questions. Should I overbore any? Also, where can I get these parts cheap? (You must remember I've been out of racing for a couple of years now.) Any help you guys can give is greatly appreciated.
#6
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Building up a 400EX motor
I would deffinatly get the oversized valves too. Last year I added a 39mm fcr fully ported head with the o/s valves and It was a good jump over how it was before.
Depending on how much money you want to spend powroll can stroke your crank put on a heavy duty rod. It would jump a 416 to 440cc's. It should give you some more grunt and you wont have to worry about braking a rod if your running higher compresion like 12 or 13:1
Depending on how much money you want to spend powroll can stroke your crank put on a heavy duty rod. It would jump a 416 to 440cc's. It should give you some more grunt and you wont have to worry about braking a rod if your running higher compresion like 12 or 13:1