Overheating 2000 WR400

Newbie here with overheating question. I have a 2000 WR400 that runs great all the time under every condition except for one; When I'm riding at higher elevation the radiator overflow tank will start boiling over on slower technical trails:mad: I read a number of the postings that suggest that richening the carb might do it but it runs great at lower elevations and I would think at higher elevation it should be richer.

I took out the carb and checked the jets:

Main jet: #165s

Pilot jet: #42

Start jet: #65

Pilot air jet: #75

Main air jet: #200

They all look stock to me. I've tried using different coolant and i'm planning to try Engine Ice next.

The previously owner did all the free mods (shortening the throttle stop, airbox snorkel/cutouts removal, and replace the exhaust pea-shooter with Vortip: he didn't cut the grey wire disconnection). The radiators looked like they may have been crushed some but they appear to be clean and clear inside.

Here are some conditions:

700'-1400', 70F-90F, low humditiy:hill/trail riding: runs great, doesn't loose coolant.

4000'-8000', 60F-80F, low humditiy: trail/technical riding: runs great, overflow tank will boil out if I don't keep moving.

Let me know if you have any ideas. thanks, Ken

The engine ice should help you with the overheating problem.

I run engine ice in my bikes with success.

The slow riding gets these bikes hot. I'd leave jetting where it is too.

Liquids boil at lower temperatures at high elevations. When you're running at high elevations, the atmospheric pressure is lower and therefore the relative pressure in the radiator is higher so radiator cap will release earlier. Coolant with a higher boiling point or a higher pressure radiator cap (maybe 1.6 bar like the YZ-Fs) will help.

Here are some conditions:

700'-1400', 70F-90F, low humditiy:hill/trail riding: runs great, doesn't loose coolant.

Lemme guess:

Carnegie, Hollister, Prarie City

4000'-8000'' date=' 60F-80F, low humditiy: trail/technical riding: runs great, overflow tank will boil out if I don't keep moving.

Let me know if you have any ideas. thanks, Ken[/quote']

Elkins Flat? Georgetown/Rock Creek? Forest hill?

Is the "209" part in your user name your area code? If so, where in the 209 are you?

Thanks for the advice. I'll try the Engine Ice when it comes in and I like the idea of changing out the radiator cap for one with a higher rating....seems to make sense. Appreciate the help! Ken

Lemme guess:

Carnegie, Hollister, Prarie City

Elkins Flat? Georgetown/Rock Creek? Forest hill?

Is the "209" part in your user name your area code? If so, where in the 209 are you?

I'm in Stcokton, Calif. You must be from the same area and yup I've ridden half of those places. My friend and I mostly ride at Carnegie but we have been to Forest hill twice, Prairie City twice and Bear River Reservior once. We've only started 7 months ago and used to do mountain biking alot. Hills are alot easier with an engine:ride:

Where you located?

Where you located?

Manteca

Waterwetter is one solution to lower temperature

Timo McKeown

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