Engine Coolant

[c-152]

Last weekend while I was on a two day charity trail ride my bike, a 1999 ec250, overheated. It was +90 out and it ran great all weekend until my dad and I got stuck behind a group of razors with no way around without really getting off trail. It was interesting as my fathers 1987 yz490 did okay.

My question is, could I have a bad radiator cap? or should I consider going away from regular coolant to water wetter or engine ice?

I know there are way to many variables in determining why my bike overheated and his, an air cooled bike, didn't but I would like to solve this.

On my last bike, a 1992 KX500, I made an overflow bottle for it and never had overheating problems again. Has anyone done that?

Thanks for any help.

[swazi_matt]

overflow bottle will not stop the bike from overheating, you will just not loose the dribbles that come out the overflow pipe as the engine gets hot. However having said that if you are on a long ride and everytime you heat upo you loose a bit of coolant, eventually your coolant level will get too low and the chances of overheating will increase.

If you didn't previously have an overheating problem it may be the cap. I previously used engine ice on my kx and it does work (well it does not boil, not sure if the engine still got hotter than it should)

[iancp5]

What is a "razor" in this context?

The Gassers normally run pretty cool. If it's not the cap might be worth checking the usual suspects; radiators clogged, clogged water ways, impeller, gasket leak. I assume if it was running lean enough to cause overheating it would've seized or sounded like it was about to.

[jostby]

Originally Posted by iancp5

What is a "razor" in this context?

I think he is referring to UTV's. I think Polaris makes the Razor, like the better known Rhino or Kawasaki Mule

It is hard to determine if a 2-stroke is overheating, especially the GasGas because they tend to run pretty cool. A person can fill the radiator to the very top and never have any problem until you actually do get a little warmer than normal (notice I didn't say "hot"). At that point about the top 1" or so is going to be forced out by expansion. It is going to steam and make a mess and stink. Most people call this "overheating". But it is normal as you need that space (the term is "head space"). A overflow or recovery tank will catch it and with the correct type cap will actually pull it back into the radiator after the system cools down. My kids '04 still has the original expansion tank plumbed between the right and left radiators. As the sytem heats up the air in that tank is compressed and the expanded/overflow fluid will go in there until it cools down and then it returns to the radiator (instead of going out the overflow).
A bad cap will allow coolant to escape out the overflow also (again, making a mess, steaming, and stinking) and again, can be misdiagnosed as "overheating".

c-152, if after overflowing and the bike cools down, the coolant should be right about at the top of the fins exposed under the radiator cap. Lean the bike just a little and it should be visible. Lower than that and you are either overheating or the cap may be bad. Do a search on this forum for "cap", the KTM cap is a little higher pressure than ours and is a good upgrade to prevent this from happening.
I hope this helps.

[c-152]

Thanks for the info

a Razor does refer to the UTV's such as a mule or rhino.

I am pretty sure it overheated as it stalled while I was on the gas shortly after the rush of coolant, stink, etc. I was coming into a clearing and had just got around the Razors and thought the increased speed would cool it back down however it didn't make the short climb into the clearing. We pulled over and waited in the weeds for about 45 minutes and it started first kick with no noticeable difference in performance. We rode for another 30 minutes back to camp at our previous pace without any trouble.

I will look into the KTM radiator cap. I might also change to engine ice.