Building a 400EX to run with the Z400?

[MAKO19]

What needs to be done to the 400EX to get it to be able to beat an LTZ400 or KFX 400? Right now I have a HMF pipe, K&N and it is jetted. That is it. I have tried 14t front sprocket and 15t front sprocket (stock) and I get beat everytime. It is not by much maybe anywhere between 1-2 quad lengths. Sometimes I get them out of the hole but once they hit 4th gear they walk all over me. What other bolt on performance parts could I get or how could I revise my gearing to beat one of these pesky Suzuki's?

Thanks!

I only had the exhaust system and filter, with my airbox on, and raced a stock z400 with just the baffle removed.

We were about dead even. It seemed like we stayed right next to each other through all the gears.

It really comes down to rider skill and traction. A piped ex is dead on with a stock z.

both quads are pretty close. The z400 is a little quicker up top it seems but the 400ex seems to have more low. If you have a pipe and the z400 doesnt you should at least run with it.

[Pipeless416]

i agree with all of the above, but if you pipe a z, its a completely different animal. my setup will pull ahead of my dads z with a full big gun evo x limited, until we hit about 4th or 5th.. those things move in the higher gears and rpms.

[leasureryan]

a damn good rider is all it takes in my opinion.

[Pipeless416]

Originally posted by leasureryan
a damn good rider is all it takes in my opinion.

its not always that easy. there needs to be a lesser rider on the z to make that work.

[Dangerous400EX]

Maybe you are jetted too fat

[pizmo 400ex]

i drag race against z400's that piped and jetted and beat them most of the time, but they do start to catch up with me at the end.

rider weight makes a huge difference and so does skill. But eqully skilled the lighter person will win if the quads are near the same or the same. well if they get you in 4th you shouldnt gear it down. You need to have higher gearing but enough power to carry it. You already have a HMF and K&N jetted. Is it jetted perfect? Remove the airbox lid, choke plate in the carb and grind down the header welds on the stock exhaust I assume your using just the slip on HMF and rejet. Those dont do a whole lot but its free HP and there is a gain. Might I suggest the curtis sparks advanced timing key too. if you dont walk him then hotcam and piston and you should fly by him with ease.

Originally posted by FoxHondaRider
rider weight makes a huge difference and so does skill. But eqully skilled the lighter person will win if the quads are near the same or the same. well if they get you in 4th you shouldnt gear it down. You need to have higher gearing but enough power to carry it. You already have a HMF and K&N jetted. Is it jetted perfect? Remove the airbox lid, choke plate in the carb and grind down the header welds on the stock exhaust I assume your using just the slip on HMF and rejet. Those dont do a whole lot but its free HP and there is a gain. Might I suggest the curtis sparks advanced timing key too. if you dont walk him then hotcam and piston and you should fly by him with ease.

holy crap, when I finally got a chance to take a big ride with the timing key, i was amazed.

I cant believe how much snappier it is now. It has so much more pep and mid-top end.

Definitly worth the money.

[lilyamaharacer4]

Ive been told that the dynatek cdis work wonders on stock motors. I have yet to find out since i put my 440 kit in at the same time as the cdi. I do lvoe the increased rev limit too.

Originally posted by DMC-4OOEX
holy crap, when I finally got a chance to take a big ride with the timing key, i was amazed.

I cant believe how much snappier it is now. It has so much more pep and mid-top end.

Definitly worth the money.

haha nice. it pulls through the RPM range quicker with it i'm glad I got it. Yet my brother still says. I dont feel any difference I dont think it did anything. I was like are you kidding? I ride his it feels like aslug when you hit the gas for it to go.

Originally posted by FoxHondaRider
haha nice. it pulls through the RPM range quicker with it i'm glad I got it. Yet my brother still says. I dont feel any difference I dont think it did anything. I was like are you kidding? I ride his it feels like aslug when you hit the gas for it to go.

yeah. It feels much more lively.

But he probably says that, because since he doesnt ride yours as much as you do, he doesnt notice a difference. When you learn the bike and ride it alot, you feel the little differences.

Im gonna have to save up for a high-comp piston and cam, then she'll probably rip. Im almost done with the shee, so I can make the 400 a little fast also.

[camden_bmx13]

I ride a completely stock 07 400ex and I smoke z400's with the "440" kit in them.
It's the rider not the quad.

[MAKO19]

Thanks for all of the feedback guys. I will look into all of the above mentioned stuff. The bike is in good shape and I really don't want to tear into the engine if I don't have too. I am looking at strictly bolt ons at this point. I also have a few questions:

Regarding the air box:

Can I just drill some holes in the rear of the box (not above the filter) so that I can increase airflow instead of removing the whole lid? Removing the whole lid sound kind of hacker to me especially since I will be riding in all types of conditions both dry and wet.

Regarding the timing key:
I know nothing about this. I am guessing it changes your whole timing curve? Is it easy to install?

Grinding the exhaust welds:
I am guessing that I will be essentially port matching the exhaust manifold to the exhaust outlets? Is this correct?

Removing choke:
How bad will this thing be to start up? I am in New Jersey and it does get quite cold up here in the winter time.

Thanks guys. I just want to put this sh*t talker to shame. Probably better traction and shifting will help me out too.

Originally posted by MAKO19
Thanks for all of the feedback guys. I will look into all of the above mentioned stuff. The bike is in good shape and I really don't want to tear into the engine if I don't have too. I am looking at strictly bolt ons at this point. I also have a few questions:

Regarding the air box:

Can I just drill some holes in the rear of the box (not above the filter) so that I can increase airflow instead of removing the whole lid? Removing the whole lid sound kind of hacker to me especially since I will be riding in all types of conditions both dry and wet.

Regarding the timing key:
I know nothing about this. I am guessing it changes your whole timing curve? Is it easy to install?

Grinding the exhaust welds:
I am guessing that I will be essentially port matching the exhaust manifold to the exhaust outlets? Is this correct?

Removing choke:
How bad will this thing be to start up? I am in New Jersey and it does get quite cold up here in the winter time.

Thanks guys. I just want to put this sh*t talker to shame. Probably better traction and shifting will help me out too.

Answered in order:

The airbox lid just snaps off. You can take it off, then just clip it back on for muddy condtitions. Or you can drill holes in the top of the lid. The lid is easier replaceable. It would be a much bigger hassle to have to buy another airbox and change it over.

The timing key advances the timing by 6*, basically making it fire sooner which makes a drastic difference on the ex. You take off the side cover, take the flywheel off (you need a puller for this), and remove the key thats already on the shaft. Then you put the flywheel back on. Theres a slot on the flywheel to line up with the key. Put on the new gasket and your good to go.

By grinding the header welds, your doing nothing but opening up the hole more so it can breath better. The factory puts very sloppy large welds on the header where it connects to the cylinder. You grind this down smooth with the rest of the inside.

Removing the choke will definitely make it harder to start with the stock jetting. The 42 pilot jet was one of the best mods I made to my quad. I never even use the choke anymore, it starts up ten times better. Theres a how-to article on how to change the pilot on this site.