Have a customer with a standard runner sp125 2 stroke water cooled. It keeps losing water out the water bottle cap very rapidly. I've replaced the bottle and cap for brand new ones as the original cap was spilt so had to be changed anyway, customer said just get the whole thing, bottle included. He's a bit like that. System all bled nicely, but for some reason its still blowing water out the top of the water bottle. I thought originally that it might be a crack in the cylinder head, but i would think that would show by having water coming out through the exhaust as well as being pushed out the bottle, i.e the push and pull of the piston, as happened on my previous LC Katana. I had another look tonight with it running on idle and the cap off so i could see into the bottle and when the engine revs are raised, although not enough the make the bike move, the water is shot back into the bottle via the normal refill pipe with some considerable force. I'm not entirely convinced for some reason that it's the cylinder head as the customer hasn't mentioned anything about water out the exhaust. Anyone have any other ideas or had the same problem?
Just had a top end rebuild, all new gaskets, but had this problem before the piston went south. Wasn't a major failure, just needed a piston kit, gaskets obviously, and a quick hone. Compression was blowing past the rings. Engine temp gauge goes to its normal position and fan cuts in as it should when it should. Doesn't indicate signs of overheating. I did think about thermostat sticking, but its not taking ages to show warm on the gauge, might try taking it out and see what happens.
Customers away for a few days now, so have time to think about it, and do some searching on the symptoms. I even thought that maybe the hoses are connected the wrong way round, and the pump is throwing the water the wrong way round the circuit. Haven't a clue really, just grabbing at straws at the moment.
