[Davecrf]

Hi
First a bit about me and the bike.
I am from the United Kingdom and was racing my 250x at a 3 hour hare & hounds event yesterday. It was a very tight track through trees so speed wasn't very high.
This bike is a 250x with a hot rods stroker crank, wiseco 13:1 piston, jd jets, air box and exhaust mod ect.
I'm running the stock rads with out a fan but with 100% Evans coolant.

Yesterday I had a max coolant temp of 280F on my trail tech!!
So I was just thinking could I done some damage to the motor? It still starts and idles fine and when I was racing I didn't notice any change in it.
I'm just a concerned as I've never had it that high before

Thanks Dave.

[Back2-2]

You are fine. If it would make you feel better, change the coolant with a fresh fill. The least to do is check the level before next ride.

[mossman77]

Maybe try a different coolant that requires water?

[JimDirt]

I would say the coolant your using should be good , and in its info it says the boiling point is "above 375 degrees" , so it should not boil out , the fan kit Trail Tech offers is quite inexpensive , and will definitely keep you from overheating , and at the least it will lower your operating temps , to set your mind at ease
http://www.crfsonly.com/catalog/product ... ts_id/5759

The slower you go , the hotter the engine will run because the only source of cooling is the air flowing thru the radiators , so if your going slow , then there is insufficient air flow to keep the temps down where you would like , so the fan will definitely help with that , since it will keep the air flowing , even at the slower speeds

I run Engine Ice in both my bikes and have a cooling fan on my 450X , its never overheated since , i run my 450R in tight single track with just the Engine Ice and it has not overheated yet either , as a note i run a 1.6 bar radiator cap on both bikes (stock is 1.1) you can get them in 1.8 bar as well , this will keep the coolant from blowing out at lower temps , since the higher the bar cap , the higher the pressure must be before it opens