07 kxf 450 OVER HEATING

friend of mine has an 07 450 kxf.. top 10 or 5 B rider down here in florida. bike keeps over heating..

Bike rides fine but when he gets rides. But after a 20 min moto he put the bike on the stand and it just poured out fluid. had engine ice in it.. everybody says its because he rides it to damn hard and the pressure on the cap isnt' strong enough.

but anybody that knows anything about bikes knows that changing the pressure of the cap is like temporary fix. keep hearing about the head warping.. Anybody have any clue..

please don't say we need to put some other kind of fluid ie( water wetter)

any other suggestions would be great.. thanks for your HELP

Sounds like he may have other issues. I would check the scavenge screen for debris (plastic worms from the cases). You could possibly not be getting enough oil to the top end, thus causing excess heat.

Or perhaps he is just revving the crap out of it, and does not know how to ride.

I just rode yesterday 96 degrees, at 4000 feet for 24 minutes straight. I am a Vet-pro/250-pro local rider, so I am not easy on my bike by any means.

But with proper maintenance these bike are pretty bullet proof.

Good luck...

The excess pressure could result from a head gasket that is leaking on the cylinder side. It might be allowing combustion chamber pressure to be pushed into the cooling system, thereby overpressurizing it and forcing coolant out the overflow. It works like a one-way valve - it doesn't allow coolant to leak back into the cylinder (I've also seen cracked heads do this).

So yes, it could be a case of a slightly warped head surface.

And you are correct, a higher pressure-rated cap would not address the root cause.

There have been a number of reports of this on the 06 models so it isn't unheard of. Pulling the head and lapping it and the top of the cylinder and installing a new head gasket may be the answer.

Another thing that may be a possibility - if this is a sand track it would be putting a lot of load on the engine. If the jetting is lean then the engine would run hotter. But it might also cause detonation that you can hear that would clue you in.

However, if this is something that recently developed and the jetting had not been changed, then this isn't a likely cause.

Pull the plug and see if it looks like it's been running lean. That's the easy first step.

If not, then address the cooling system.

Post back when you find out what it is - it might help others with the same problem.


a faulty radiator cap can do this.a new cap is only$25 and he could go up one size(on pressure)while hes at it.also make sure he isnt leaking anything out the water pump weep hole.a guy around here had a small amount leaking out the weep hole and his bike would overheat like that.he could also have a broken impeller in the water pump or a bad impeller shaft bearing.removing the water pump cover for inspection is simple enough.make sure theres no oil in the water and no water in the oil.he could be leaking pressure internally.any pressure leaking out of the system will cause overheating.

first off thanks for all the help. Him and his father a damn near pro about fixing bikes. They rebuild 4 strokes all the time and can't figure it out. They have yet to take apart his bike and see. He did order a new cap same pressure and plan to try that. After that doesn't work i believe they are going to check and maybe mill the head down and put a new head gasket. Once we get into the bike we will let everybody know what is the prob on all these bikes that is causing this problem. I know some never have it and others all have the prob.

thanks again for all the helpful hints

i to also have this prob. on my 06 450. waiting on piston. but i beleave head warpage, will find out soon.

if you have a peice of 1/4 in plate glass, you can tape some 320 or 400 grit emery cloth to it, and set the head on it grabbing it evenly and on the bottom side move it in a circular motion back and forth will show you what you want to know, very easily cleaned up, and trued, done quite a few this way, most all I have done have been warped noticably, think it is mostly due to improper torque from the factory, check it I think you will be surprised just finished my sons 06 doesn't leak a drop now,

have not rebuilt yet, but it has stoped running hot and losing coolant. go figger.

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