im new to this i just needed some help figuring out mods for my 400ex. I have stage 2 cam, ported and polished, 426 big bore 11:1 compression piston. Its going to be for racing. i know i could get a 450 but id rather use my 400. What other mods could i do to get more power and speed. Also what exhaust is the best to run. Thanks for the help

 

You can get more power many different ways, im currently building a 400ex with basically the same set up, 426, stage 2, port and polish, i have the fmf titanium 4 exhaust with fmf powerbomb headers and those work great Im also going to install the curtis sparks timing key Ignition Advance Key, Honda 1999- TRX400EX and that adds 2 hp

Your welcome, Karson

 

Thanks i heard a lot about them pipes. What exactly does the timing key do?

 

Timing keys are not for high compression motors.... It should say that on Sparks site.
If you want to add to the motor, let it breath. Uni filter, 450r carb, powerbomb header and any decent pipe that that will fit the header. BTW do you have HD head studs?
The best mods you can do to get more speed are suspension. The ex rear shock is ok to start with providing you adjust it. Front shocks suck, total junk. Plain old 450r front shocks are a improvement and you can have a shop change the springs and revalve the shocks for your lbs and riding style.
You also want to think about widening the stance. Get a good handle bar, good as in a comfortable height. Also the ex front brakes are weak and fade fast. A set of stainless braided lines really help the front brakes.

 

Thanks my friend said they aernt good with high compression motors. I'm planing on get a 450r carb and full big gun exhaust. I don't have hd studs right yet. I hear alot of people talking about the suspension helping alot just curious how does it give you more speed? I have in plans to lower and widen it to give a a nice stance.

 

A good suspension wont make the ex go faster. But they will allow you to ride faster over harsh terrain and soak up the landings from bigger jumps or bad landings. It will be more of a comfortable ride.

 

oh now i understand its hard to find a good suspension set up for a decent price thats why its hard for me to go with really good shocks. For like flat track/drag racing what kinds of internal stuff could i do other than what i have already.

 

Bigger valves. You can shave the flywheel. If you take a few oz off it will rev much faster. But it will loose some of the torque. Check the clutch. You may think you clutch is fine. New fibers, plates and hd springs make a huge difference. Keep a eye on the clutch basket. With the extra power the clutch fibers and plates will make grooves in the basket. Making it harder to shift. The grooves can be filed out.
The 450r carb is 04-05 only. This carb needs a adapter or modify the intake boot to mount. Think you need to remove the hot start and plug the port with silicone.
With 11:1 are you running on pump gas, race gas or a blend?

 

its a new clutch in it im actually just about to finish up the build to get it running actually. Does teh 450 carb. make a big difference in acceleration cause i heard it does just not sure rather someone who knows alot answer it for me. What do you mean remove the hot start? People say i can get by with 93 not sure yet might have to do 50:50

 

The 450r carb will help you all around. Hot start is not used on the ex.