I have a 2002 660 r raptor, and I started to have the coolant leak out of the overflow. I changed the coolant this spring, and purged the air out according to my Clymer manual. Now it fills the overflow from the radiator as it warms up, and doesn't suck it back in, just keeps filling and dumping out the overflow tank on to my swingarm. My overheat light comes on too, but luckily I always catch it right away. When I let it cool off and open the radiator it's always down almost 2 quarts.
I called the dealer and talked to a mechanic I have used with decent results, and he suggested to change the thermostat. Did it yesterday, and same problem today. Anybody have this problem before?
Any tips to the right direction are appreciated. I hate to take it to the dealer, because they are always a min. $100 to look at something.
maczzz

 

Check the cap.
Is the fan coming on?
May be a bad head gasket.

 

Head gasket blown or cracked head.

Hows the compression?

 

Ever since I put in the 11:1 piston my raptor pukes coolant too, but I still have coolant in the radiator and the fan does come on. I think I have to re-tighten the bolts, just havent had time. Have you had your engine apart?

 

The guy before me had the engine beefed up on the top end, cams, ported and polished, but left the stock piston. I bought it in fall 2003, no problems til recent. I would think if its the head gasket, either it would leak from the head, or blow out through the exhaust as white smoke if it went in the cyl. It fills up the overflow reservoir and then spills out the overflow hose. I stopped in a honda dealer today, he said take the rad. cap to a radiator shop to check the psi on it to see if its working properly, but I can't find what the Psi is supposed to be on the stock cap. The yammy dealer wants $38 for a new radiator cap, hate to by it and thats still not the problem.

 

Ps. no i haven't check compression yet tho. I'm guessing like a standard cyl, 140+ cyl. pressure would be good, if it doesn't loose pressure to quick, probably not the head or gasket?

 

You can have a leaking head gasket and not have the other symptoms you have mentioned.

 

Save yourself the heart ache and replace the head gasket and torque it back down with the correct specs. I have had this happenn before and it was exactly as you are describing. Make sure to tighten down the bolts in a progressive manner ( a little at a time and work your way up to the recommended torque.) Hope this helps