cheapest place to buy 250R aftermarket radiators

[EAT_A_450]

ChrisD, Have you ttried the cfm coolers? If so how much did it help? How much did the Rad's bring the temp down?

[EAT_A_450]

I have probably a dumb question but........ the stock head gasket restricts the water flow some through the cylinder because it covers up each water jacket a little and the stock cylinder has smaller water jackets than the prox cylinder which has o-rings instead of a head gasket. My question is couldn't the water be flowing through the rad's too fast for it to cool properly? Could that be why the prox cylinders heat more than the 500's do?

[Dammit!]

I have probably a dumb question but........ the stock head gasket restricts the water flow some through the cylinder because it covers up each water jacket a little and the stock cylinder has smaller water jackets than the prox cylinder which has o-rings instead of a head gasket. My question is couldn't the water be flowing through the rad's too fast for it to cool properly? Could that be why the prox cylinders heat more than the 500's do?

That's not a dumb question at all. You might be on to something with that. If the coolant is moving through the system too fast it will definitely heat up. I've read reports from several people with similar setups to what you have and you're not the only one that has that heating problem. Instead of spending big money on rads, you might try to come up with a way to slow the coolant flow down a little and see what happens.

[EAT_A_450]

Thanks! Glad some1 is on the same page. I'm gonna call prox and see what they say. Also, I tore down my water pump/ counter balancer yesterday and found the bearings on the balancer were wore slam out. Now the gear was fine so the water pump was turning at the normal speed but not smoothly- wonder if that coulda been an issue?

[Andrew_250R]

I have probably a dumb question but........ the stock head gasket restricts the water flow some through the cylinder because it covers up each water jacket a little and the stock cylinder has smaller water jackets than the prox cylinder which has o-rings instead of a head gasket. My question is couldn't the water be flowing through the rad's too fast for it to cool properly? Could that be why the prox cylinders heat more than the 500's do?

If you take the thermostat out of a car engine and run it the engine will over heat. You have to have some sort of restriction, in the car it is a thermostat.

[Tri-Z Pilot]

maybe try running a t-stat setup from a tri-z? i think te t-stats are more there for a faster warm up though. i am also thinking that stats r there to run your engine warmer as too cool can rob power, a stat sticking closed will cause you to overheat, removing it will cause you to over cool.
this is probably different from bikes though as cars rads have a bigger surface area for more effective cooling, and they have a secondary cooling source via th cooling fan.
just some food for thought.

[EAT_A_450]

actually no thermostat can make it heat as well because the water can flow through too fast for the radiators to cool it which imho could be the problem on the atc 250r's because the radiators are very small anyways.

[Tri-Z Pilot]

hmmm. i never had a car overheat without the stat, was always over cooling. i see the principle though. if that were the case wouldnt more bikes overheat, the tri-z is the only thing i know of with a t-stat.

[Andrew_250R]

hmmm. i never had a car overheat without the stat, was always over cooling. i see the principle though. if that were the case wouldnt more bikes overheat, the tri-z is the only thing i know of with a t-stat.

All my buddies who derby cars put a restriction inplace of the thermostat, because just running with nothing will cause the cars to over heat. I am sure the thermostat won't keep the car cool enough either.

[NINJA]

Typically a two stroke engine with a cooling system designed with a thermostat will run too hot if the t-stat is removed. The reason being is that the coolant doesn't stay in the hot spots long enough for the heat to transfer to it and be carried away to the rads. A 2-stroke engine designed with a cooling system that doesn't utilize a t-stat relies on the flow rate of the water pump impeller mainly for temp control. Naturally a high comp. modified engine will produce more heat and have a higher operating temperature than a stock engine. If your impeller has worn bearings or a worn housing, then this is most likely your culprit. If your rad cap isn't functioning properly, this can overheat you also.