kx 500 over heating?

[cooltoy]

Hello,I just bought a 1987 kx 500.The bike is in great shape but needed a new top end.I did that and it seems to run excellent EXCEPT tonight when i got back from about a 5 min ride it was extremely hot.The coolent was so hot it was litterely boiling loudly for at least 5 min.I am thinking maybe the water pump isn't working.I hate to pull the pump cover just to find that it is normal for the 500 to run that hot.For my coolent i am only running water with about 3oz of water wetter.Maybe thats the problem?I have run water wetter in other bikes with great results.So what do ya think,normal?, bad water pump?, bad coolent?.
Thanks for any help,  bill

[Paul]

I run Engine Ice in my 500 and haven't over heated once since Jan 2001 when I bought it - it's a 2001. I live in Arizona and riding in 100+ temps is not unusual. Sounds like you may have a couple pinched radiator viens or something wrong with your water pump. If its the pump I hope it's the impellor and not the drive gear.

[GREENCANNON]

Not sure of your specs. But my 87 seems to overheat alot. The biggest factor so far other than mechanical failure is jetting. If I jet for crisp throttle response it seems to overheat easy, evn with a decent looking spark plug reading. If I jet it just a tad rich the overheating seems to clear up. I also agree with the radiator theory, pinched vane or even some corrosion causing blockage. I'm always tinkering with this bike cause I have a new 5 for the weekends. I'll keep you posted if I find anything new.