450F YZ450F 2005 roll starts but won’t kick start

Hi everyone! I am new here so apologies if I have not formatted this correctly.

I have a YZ450f 2005 model that my friend blew the head on valve bouncing. It was pretty ugly inside to say the least I have rebuilt it (new piston, barrel, and entire head), but sadly I can’t get the thing to kickstart anymore. It used to start first pop pretty much every time. I can bump start it then it runs fine, just can’t kick start it.


I’ve checked compression, sitting at 150PSI. The cam chain appears to be set correctly, lines up the I on the crank then the dots On the cam with the case. I’ve put in a new spark plug, didn’t change anything. Auto decompression seems to be working fine too. I’m not really sure what else now, was going to take to the mechanics in town to have a go but thought I’d try my luck here first ☺

Any ideas what might be up/need to check? Any help would be greatly appreciated!
Cheers,
Ryan
 
150 psi on the compression test is actually high for an auto decompressed engine. When you said head work....What was done to the head? Have you replaced the cam chain? What do you have the valve clearances set at?

Paw Paw
 
Top