Hi this is my first post, I have a wr450f which would start. At first I tryed to start a start it replaced the spark plug and after about 30min the engine warmed up and it started. I took it to the mechanic he had the same thing happened, he did a compression test and it was down by 30psi, and the piston and barrel was glazed and the rings where rounded. He repaced the barrel and piston and the compression went back up. Start first go warmed it up then we let it cool and tryed again and it wouldn't start, but it would start when its warm after kicking for ages, any ideas.