i just installed a 14 tooth front sprocket on my stock 400ex. all i can say is WOW! best part about it is that it only cost 8 bucks from Rocky mountain ATV. It puts the atv right on the RPM range where you want it. I really havent noticed any drop in top speed. Seat of the pants feeling is awesome in the low to mid and pulls hard to the rev limit. Anybody looking for cheap mods, this is definitely one of them. Highly recommened, great for trails, MX, and dune riding as well as climbin hills. Definite Thumbs UP. Plus installation is a quick 30 minute job. Next up is an filter and exhaust!

 

I agree...the 400ex I sold did'nt have enough power to hit the rev limiter in 5th....but with a 14 tooth front sprocket, it would. Did'nt seem to loose top end speed since I was gaining RPM's with the 14 tooth sprocket.

 

I agree too. I did this mod and it made a big difference in the dunes. With a set of 8 paddle 20X10 Haulers and that sprocket I fly through the sand. With the super smooth shifting of the 400EX and rapid acceleration from the smaller sprocket and paddle tires, I can rip through all the gears so fast it's like an all new machine

 

Another cheap mod is the advanced step key ignition.
It costs $15 and gives you a lot more rev and I think midrange. I bought mine from Curtis Sparks Racing.

 

Does a 14 tooth c/s really make that much of a difference on the 400?? I've own different bikes over the years and changed sprockets on them and I've never noticed a change in performance. Sorry just a little skeptical.

 

i can safely say the way to go for mx or drag racing is what i did....i can pull most highly modified ex's easily....what i did was put 18 inch turf tamers on the rear, and re geared it...i went up to a 16 or you can drop 2 in the rear and stay stock counter sproket....i can smack it dead stand still in 2nd and it spins like a bat out of hell...and can barely be moving the slight bit and be in 3rd gear and that thing will scream when given a lil gas.....my bros 99 was good and broke in and always gave mine a run for its money and beat me most the time, his is modded too, and he cant come close to beating me now.......

 

I also added 18 inch turf tamers and the 16 tooth sprocket. And it loses a little on the bottom but the 400 has enough yo go around if you keep it in the right gear. And now it pulls real hard in the mid ant up to the top.

Chris

 

i dont think it lost much bottom IF ANY! i can still start in 1st really strong...but now im able to start in 2nd which is the gear you wanna start in when dragging and racing out of the gate during mx.....this helps you already be a gear ahead, and those tires and gear help it scream out of 2nd where as stock you can really start off in 2nd well at all.....

 

Ok what did you do to yours that made is so much faster off the line? Put 18in. turfs on the back and a 16 tooth front sproket? I race MX and am about to purchase 18in. rears, Will a 16 or will a 14(like the previous msgs said) front help me on the track? What is it stock? Thanks

 

hey LDJ. what is curtis sparks web site?