White smoke from the head.

Well today I go outside to start her up. It starts up ok. I ride about 2 min... and as I get to where I was going...I went to shut her down and I noticed a weird noise(sounded like somethin was spitting air. I looked down and saw white smoke. I checked oil...and it was good and I was checking the plug anyways. So I did that and the color looked good. I started to crank it over but not enough so it would start. I could feel air shooting out of the head right beneath the spark plug. Im hoping and guessing that its just a gasket. So I tried starting it and Its having a hard time like it doesnt have enough compression. Is this the problem and what could cause this. I just got it ported and polished so the guys had to of put a new gasket on there when they put the head back on.

Probably a bad gasket or no gasket at all - lots of motor places use the gasket maker **** for top ends and chuck the gasket (thats a big no-no) it almost always fails. Anyway the air leak in your motor due to the fucked gasket will cause it not to start. Just replace the gasket and you should be golden.