I HAVENT SEEN ANYONE TALKING ABOUT THIS BUT PUT YOU ON A 16 FRONT SPROCKET AND YOU WILL SEE THE MOST GAIN OUT OF YOUR 400EX YET WITH A BOLT ON!
YOU HAVE TO GRIND THE CASE SAVER A LITTLE TO FIT BUT THATS IT. MY SONS 400EX HAS A PIPE,DYNOJET,K&N FILTER AND ALL I DID TO MINE SO FAR IS THE SPROCKET AND HE CAN BARELY HANG WITH ME FOR 1ST AND 2ND GEAR AND THEN I LEAVE HIM IN THE DUST. NO COMPARISON AND IT DOESNT HURT BOTTOM END EITHER,ALMOST FEELS STRONGER! IT WILL WHEELIE IN 1ST,2ND,3RD WITH NO PROBLEM. THESE THINGS ALREADY HAD TOO MUCH BOTTOM END. NOW I KNOW WHY I WAS GETTING OUTRAN BY MY BUDDIES,THEY TOLD ME WHERE TO GET THE SPROCKET AFTER KICKING MY SONS BUTT OVER AND OVER AND WE COULDNT FIGURE OUT WHY, IT ADDS A GOOD 5MPH OVER STOCK. YOU CAN PAT THE GAS ON A STOCK GEARED ONE. TRY IT YOU WILL NOT BE SORRY!

 

Isn't it geared to high to go up steep hills? If not it sounds good!

 

A 16 toth sprocket will hurt excelleration (quickness) and make it harder to get enough speed to clear doubles on MX tracks.

 

Im talking trail,drag racing,pleasure riding! mx or flat track requires gearing to track and tires to track, If you want to fly try it. It doesnt hurt nothing on the botom end! mine wheelies easily in 1st, 2nd, 3rd and fourth if you try. They have too much bottom end to begin with! and no top end. TRY IT! YOULL LIKE IT!
IF ALL YOU ARE DOING IS FLAT TRACKING GET A 250R!

 

HURT QUICKNESS? BULLSH.. IM talking trail,drag racing,pleasure riding! mx or flat track requires gearing to track and tires to track, If you want to fly try it. It doesnt hurt nothing on the botom end! mine wheelies easily in 1st, 2nd, 3rd and fourth if you try. They have too much bottom end to begin with! and no top end. PUT A PIPE,KN,JET KIT AND ALL YOU HAVE IS BOTTOM END, RUN UP AGAINST A 400EX WITH 16 TOOTH SPROCKET WITH STOCK TIRE HEIGHT AND YOU ARE IN TROUBLE RIGHT FROM THE GET GO,I HAVE TWO, IVE DONE THE TESTING AND I KNOW WHAT IT DOES! INSTEAD OF LEAVING IN SECOND YOU WILL LEAVE IN FIRST AND NEVER QUIT PULLING! TRY IT! YOULL LIKE IT!
IF ALL YOU ARE DOING IS FLAT TRACKING GET A 250R!

 

Very good point and I would add that any bottom end lot is regained with a pipe and filter. This is a definite must if you find yourself bouncig off your rev limiter. Pipe, airfilter, jetting, a rev box and a 16 tooth f sprocket are good for about 7 mph. Also for quick starts try using 10' alumium wheels in the rear with a light durable 20' tire a la Fast Trekkers. Cutting the the rollins mass on the drive tires gives you quicker acceleration and better braking.

 

Sounds sweet!!
I want to try this on my 200SX, I need a new front sprocket anyways, so all you do for better speed is get a bigger front sprocket?!?!

 

Put a 35 on the back and you do not have to cut the case saver. A rear sprocket is only $25.00 for a after market one

 

I dont even know of a 35 for a 400ex? but that would be too much. Changing the front is about equivalent to two teeth in the back not four. But with the torque the 400ex makes the combination is there for the front swap not the rear. Has to do with the transmission gearing too. The front one will set it on fire! about five to ten bike lengths over one not geared that way. I have two 400exs and have tried it, my son kills me right from the start and never quits pulling away. I can hang with him for a second or two and thats it. The 400 produces so much torque that the 16 tooth doesnt hurt it. If you have a pied and jetted 400ex and want to wake it up try it then talk. Or get outran like we did untill someone shared the secret!
Renthal makes it for the 400ex doesnt thast tell you something? Honda Dealer can get too.

 

shockwave

I have a couple of questions:

1. How much grinding did it require on the front chain guard?

2. Were you able to use the stock chain without adding links?

3. Where did you buy it from? I see Dennis Kirk has them from Renthal.

Thanks for your help.