Coolant Problem!

[jackrb100]

The coolant level dropped after both my races last weekend and its not pushing it out through the overflow. I had it filled to the low line like always and it emptied the tank and went down a bit in the radiator. My engine oil and tranny oil don't seem milky. I ran it to see if it was because the radiator wasn't bled properly when the coolant was put in. After 10 minutes of running it droped twice I think both times were when the thermostat opened. It did that twice and then stopped and didn't do it again so could it have been just that it hadn't been bled properly. And there wasn't any bubbles at all so I can't see how it could be head gasket. I have just rebuilt the top end 3 races ago. Any help is appreciated

[eastside 400]

are you sure it didnt push it out the overflow? it could possibly be burning it, take the spark plug out and look in, if the piston is really clean then it's probably burning it.

[jackrb100]

I am not totally sure it didn't go out the overflow because the tip of the overflow pipe was wet but there was no coolant around the bike. Do you think it would push that much out if it wasn't properly bled. Took the plug out and piston is not that clean it looks normal also the plug is the correct colour. Thanks for the response.