Well let me start by saying I've had my 558 kit in for about 4 years and no problems. I was riding a couple of weeks ago and my Predator got hot. It was a long ride on the road to get where we were riding, so I just figured that was it. And when I say it got hot, the light never came on and the fan seemed to cycle just like it was supposed to, but it was blowing coolant out of the overflow cap. I let it cool off, filled the radiator, and rode some trails. All was good for a while and then it did it again. Let it cool and rode it home, when I got home same thing. Coolant tank spewing out of top, and radiator about 1/2 full. I'm thinking head gasket, or thermostat. I tore into it last nite and found a perfectly good headgasket, so I rip the thermostat out. Put into a pan with a candy thermo and it opened at exactly 71 degrees C, just like it's stamped. Ideas anyone. I'm going to replace thermostat and headgaskets just because I'm there, but does anyone have any other thoughts. And I did check my radiator, and the fins are clean.