Need engine help
So I bought a 89 Polaris trail boss 250 last weekend. Guy said it was seized but it turned over for me and sputtered on some ether. Rebuilt carb and couldn’t get it to start at all. Checked compression and had 60 psi. Ordered a top end kit (piston, cylinder, rings, and gaskets). Installed all of the parts according to whatever manuals I could find. Went to check compression again and still was only getting about 60 psi maybe 65. Did I do something wrong when installing?? I put the piston (wiseco) with the arrow facing forward, ring gaps are on the pins on the piston with letter facing up, and everything was torqued. I’m also hearing a slight hiss when pulling the cord on the compression stroke and checking compression with exhaust and intake off.