On my 2004 WR450 I replaced my damaged cylinder head and installed new cylinder rings. It’s back together now, but it will not start. The electric starter is straining to turn the engine over. I also noticed air coming in and out of the crank case tube. When I re-installed the exhaust cam, I had to push the front timing guide down a bit, ¼”. I was wondering if that is normal? I triple checked the valve gaps. They are good. Any suggestions ideas are appreciated.