Will not start after installing hot cam stage 1 in my 99 400ex it will crank and crank if i give it gas a little it will backfire pretty loud. Checked timing and valve lash i adjusted to hot cam specs. 13mm intake and 15mm.exhaust..help plz

 

I am assuming you mean 0.15 and 0.13mm valve clearance on the compression stroke. Most likely problem is you haven't got the cam timing right. You assume that whoever made the "hot cam" put the timing mark in the right place. Best to check it with a timing disc. Did you have the flywheel off when working on the engine? If so, and you didn't get the key in correctly, both ignition and cam timing will be out.