250-500cc Water coming out of exhaust

Havent started the bike for a couple of weeks.

Tried to fire it up and it took ages. (im pretty sure the kids put water into the muffler as it was out the back and they have been playing with the hose alot lately)

Finally got it started and running but coolant was coming out of the exhaust.

The coolant in the radiators now looks brownish as apposed to a stark green too.

Pulled the head off and the small inner o'ring looks in bad shape.

Question:
If coolant is leaking into the air/fuel exhaust system and coming out of the exhaust is it head gasket?

From my understanding the base gasket shouldnt make a difference because there would be no water jackets going into the crank cases therefore no way it could suck coolant through to the crank case.

So it should only be the o'ring in the head allowing exhaust gas to push into the water system and then suck through into the combustion chamber.

Is there anything else I could have missed?

Stu

It's probable on a cold motor that it may have sucked oil through the bad o-ring causing oil contamination within the cooling system when you were starting plus a pressure build up.
Also, if the pipe is full of water and sitting around for a while, will cause corrison within the power valve through to the cylinder etc.

Pressure testing the radiator could have also indicated a faulty seal somewhere.

Got a pic of the head and o-ring?

Yeah and slap a new base gasket on and they can leak as well.

Inner o'ring had failed in a few spots.

picked up two 75.92 diamater o'rings this morning but could not get the 75.7.

Hope it seals

I got my from CBC bearings!!!
So long as it sit's within the grooves you'll be right if not get a spare and the guys from CBC (or similiar) can make you one up to the exact size if needed.

I got mine from AWB bearings...the only thing that worries me is the heat rating. 120 degrees C.

I will slap it in, take it for a strap and see how it goes.

Stu