[What happens when you overheat an R motor?] - ATV Riders Forums - Honda, Yamaha, Suzuki, Kawasaki, Polaris, CanAm, Arctic Cat, Kymco ATVs

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What happens when you overheat an R motor?
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Posted by: Iliketogofast

This morning I put back together my R. after a long time of downtime.

Shortly after that a few buddies showed up asking if I wanted to go to the local sand pit for a couple of hours. The only thing was I was out of radiator fluid... So I put just water in it.

I think it was overheating because it acted very funny at high RPM's on the way home, but ran smoothly on the way up. When the power was reaching the blast-off point (top end), it would start bogging and hesitating rapidly.

I figured it was overheating due to the water boiling and foaming or something like that. Is this possible, and what are possible long term damage if any?

Posted by: firefighterjosh

your quad could blow an engine if it gets too hot. This is what I say. If you don't have the correct fluids to ride then don't ride.

Posted by: Iliketogofast

Yeah. I know it was stupid, and I wasn't going to go, but I talked myself into it...

I figured it would be alright if I stopped often (Which I did) but the long ride home was sort of dangerous so I didn't get any stop time. We had to travel some country roads, and some of the local police would have stopped us even though we had helmets and were riding respectfully to traffic and homeowners. None of them around here will say anything, but we were in uncharted territory, so to speak, on that ride.

Posted by: hollywood250r

Actually, water transfers heat better than antifreeze so it will keep you r runnng cooler. Water is not the best for keeping the coolant system running very long. Antifreeze also lubes the seals in your coolant system and protects the Al. The cause if it running hot would not using 100% water for coolant but other causes like, jetting, air leak, mud on radiator, radiator to small for motor (big bore), etc.

Posted by: Iliketogofast

I thought water would be okay, but I didn't know it was better (doesn't antifreeze have a much higher boiling point?)

I discovered the problem, however. The air/fuel screw was like twelve spins off of what I usually keep it at... After I finished that it ran pretty well, but since it got hotter outside it still seems to be off in the jetting department. The jetting seemed like it was fine, but it was fouling plugs with the airbox lid off. My problem is a mixture of bad gas (old and improperly mixed) and atmospheric changes since my last fine-tuning.

Posted by: 250R-Dee

Here's an interesting report about coolants and water in the radiator.

Overheating can cause hotspots in the cylinder which in time will lead to a blown motor.

Posted by: zedicus00

water under presure (like in a radiator) wont boil at a temerature that yur engine should ever get it too. also the purer the water the less likely it is to boil (i use distilled water) and do NOT run standard green car antifreeze. you want a silicate free antifreeze for the R. you can run stuff like engine ice, that neon orange dexron anti freeze is fine too... about 2/3 water 1/3 that stuff. or half an half if you actually have a freezing climate during any time of the year.

and run a radiator cap out of a honda civic. itl get you another 3psi in the cooling system which should net you a 15 degree cooler running temp. also inline coolers help, you want atleast 14 fins to do any good.

Posted by: Aceman

I'm curious.....why can't you run green antifreeze? That's what I have in my R right now, it says it's safe for aluminum.

Posted by: zedicus00

silicates are very hard on the R's water pump and seals... it wont cause a problem right away, ive ran it in my R for short times before. what it does is whare out the seals a lot quicker then a good non silicate antifreeze will.

(green antifreeze has silicates, dexron and toyato orange and dark red respectively do not contain silicates, niether does engine ice and other performance antifreezes)