Does anyone know what a stock kfx400 would need to race motocross? I want it to run with all of the other quads and be able to beat them if my riding is good enough. I am planning on getting a kfx400 in mid march and want to race it. I need to know what to add to it. Thanks

 

I don't know about the KFX's but Z's have had some trouble breaking the frames around the shock mounts. So I would prolly gusset the frame just to be safe. Can't really tell u about engine mods. U might try goin with a kit from Trinity. JMO

 

open up the airbox it is a HUGE restriction, as always go with a full (or slip on) exhaust and properly rejet.

Some others might recommend (but I don't necessarily because I lack experience with them)
- Chop the plastic
- Rev kit
- port and polish
- new handlebars (the stock one flexes a lot)
- titanium valves
- fuel injection
- carburetor off of a Honda 400ex (no joke)
- hot cams
- high compression piston
- upgraded rear axle
- upgraded suspension
- +2 arm-thingies (whatever the proper term is)
- new tires
- new stickers [img]i/expressions/face-icon-small-happy.gif[/img]

 

just a question corpsi, how do you put fuel injection on a carburated engine without extensive mods?

 

I don't know how the rest of the guys at your local MX track are but chances are you could go there with a stock KFX 400 with just nerf bars and a kill switch and probably hold your own very welll....For example I went to a D-13 race a year or two back and a guy with a STOCK Lakota placed 4th out of 12 quads mainly cause the other riders didn't know what the heck they were doing LOL. But I'd go with a slip on pipe and a take off the air box lid rejet the bike and go for it. See how you do from there and then as you get the money build the bike up with new a-arms, swingarm, and, shocks.

 

I don't know how the rest of the guys at your local MX track are but chances are you could go there with a stock KFX 400 with just nerf bars and a kill switch and probably hold your own very welll....For example I went to a D-13 race a year or two back and a guy with a STOCK Lakota placed 4th out of 12 quads mainly cause the other riders didn't know what the heck they were doing LOL. But I'd go with a slip on pipe and a take off the air box lid rejet the bike and go for it. See how you do from there and then as you get the money build the bike up with new a-arms, swingarm, and, shocks.

 

There was talk of a DRZ fuel injection conversion kit, but I have yet to find it.

I imagine you can add an 02 sensor, small engine management computer, temp sensor and a fuel injector to get it to work.

 

would taking off the filter lid damage the motor? i know it'll give it more power but it won't even hardly run without rejetting...which jet is recommended for this from stock? no pipe

 

Stock is a 130.
I would try a 145 and adjust the needle up (richer)

BTW: These are Mikuni jet sizes, not dynajet (dynojet?)

 

The first thing your gonna want for mx after the nerfs and kill switch is shocks. Tons of extra hp isnt gonna help if your getting worn out and beat up by your stock shocks.