First off Im really new to the ATV seen.. I just bought a brand new 06 kfx400, It has < 10 hrs on it. And now for my problem Ill get it out, Turn fuel line on, starts right away, sounds great, it runs great idle and riding around... BUT after about 10-20 mins of beating on it, it seems to just kinda die on me and will take about 5-10 mins to start back up and then after it starts runs fine.. but I never run it long enough to see if it does it again cuz i stop riding after..before this Ive took it out on a couple long period riding ventures and NEVER had this problem... until now.

One observation ive seen in the past the radiator fan kick on before but I never see it come on anymore..

Could it be over Heating?

What should I do?? Im afraid of riding it cuz I dont want to break it, if theres something horriblely wrong.

 

When it dies, does it feel like it's running out of fuel (gradually) or it cuts out instantly? If it feels like running out of fuel feeling, it could be fuel tank venting system - carb's fuel bowl ging empty. To test, ride "easy" with the fuel cap open and see if you can duplicate the problem.

 

bad gas?

 

You might have answered your own question. Check your temp. sensor or your fan fuse(if so equipped).

 

OK So today I took it out.. Started just fine like normal then took down the block then back into the driveway was just fine until I stopped... then the engine started to idle funny and when I push the throttle in it doesnt rev up it slows down and dies..all hoses are unkinked.. still didnt see the fan kick on but... with the short disance I rode I highly doubt it was have over heated... but after about 5 minutes of playing with the throttle it would then idle fine and rev up when pressed in So.... IM confused

I tried an easy run with the cap open like Hayashi said.. did the same thing

 

Even though your not running it for long the fan should still come on so i bet there's something wrong with the fan. You can check the wires or it may even be worse than that. I hope that helps.

 

Your fan not coming on problem (may not be a problem) and your engine stalling problem are not probably related. But let's check it out anyway.
On the rihgt side of radiator, there are 2 brass colored fittings with wires hooked up. The top one is the coolant temp switch that turns on the overheat lamp by the ignition key. The bottom one is the cooling fan thermo switch that activates the fan if it senses 190 F or higher. If there is really a problem and the fan is not coming on, 2 possibilities exist. First the fan could be at fault. Second could be the faulty fan thermo switch on the radiator.
Let's check the fan.
Apply 2 VDC voltage to the fan by connecting + to the Orange wire and - to the Brn/Red wire directly from battery or other source of 12 VDC.
Then, let's check the fan thermo switch.
Remove the switch from the radioator and submerge in boiling water (212 F) which checking the continuity between Brn/Red wire and Blk/Wht wire. The switch should close at that temperature (190+ F).
I still think your engine stalling problem is fuel related - slowly dying. When the engine dies, remove the fuel drain screw from the bottom of the fuel bowl of the carb ASAP. If no fuel comes out, then your carb is running out of fuel somehow and go from there.

 

Schweit, you should have a 10amp fuse that protects the fan that you need to check. Its located on the right side of the bike near the temp sending unit( near the radiator). Its a little black box with 2 red wires leading out of it. Its attached by a rubber bracket. Anyways, let use know what you find.

 

it sounds like a fuel problem
either u have bad gas or the carb bowl is dirty
and as far as the fan goes i would check the fuse before i worried about it.

 

or u might have a little water in your carb
i would drain the bowl or clean it