I have an unusual one. My 400 Scrambler 4x4 overheats after about 20 minutes into a ride. The little light comes on, and I stop, let it cool (in idle), the light goes out, and then I am away. After this I can cane it, nail it, ride it at full for 5 minutes solid with out letting off down the deach, gnarly tracks, mud, racing, whatever I throw at it, it will not overheat for the rest of the day!

I idle it to warm it up for 5 mins min before I ride every time. take it easy for the first few miles to get good heat into it, then I am away. Then it over heats and I can not work out why. The radator is clear, I have a Super cooler and cool head from Pro Design, run 50/50 anti-freeze/water, bottle is on max, radiator is to the cap, I have a switch to keep the fan on. I have a 1mm oversize Wiseco piston, and a few HPD mods. Tires are stock sizes in the XCT Holeshots.

Can anyone help? Please?

 

You may have an air bubble in your cooling system. On the top of the stock head (don't know about the super-cooler) there is a bolt with a phillips-screw slot in the center of the head. Loosen that screw a little, and start you engine, and look for bubbles, If any air at all comes out, that is your problem. If not, I guess keep looking.
Like I said, I don't know if your super cool head would have that or not, but I sure would look

 

maybe your temp sensor is wrong...

 

With the billet heads, you just have to loosen the hose-clamp holding the hose to the head. Wiggle it loose til you get coolant coming out. Also, have you tried Red Line Water Wetter?? I don't even run a fan anymore.

KT

 

Hey Modquad

Why would you loosen the hose clamp? I can't see how this would restrict the coolant flow, or does it serve some other purpose?

Also what is Red Line Water Wetter? I have not heard of this before.
Thanks for your help.

 

I assume that modquad was meaning you need to loosen the hose clamp to let the air out, as there must not be an air bleeder in the billet heads.

 

Right. Got it now! I will give it a go. I had bled the system after the last rebuild, and ususlly bleed it by taking the cap off the radiator, and reving the snot out of it.

 

You guys figured it out. The billet heads don't have the bleeder like the stock unit. You loosen the clamp on the hose on the head. wiggle the hose a little loose until you get some coolant to leak out. The Red Line Water Wetter is around $7 per bottle. You mix 4 ounces per one gallon of distilled water, this will lower your coolant temp approx. 20degrees. Beware, this doesn't have anti-freeze qualities, so come winter, you better change it out.

KT