Too much compression. adjusted the valves and it got worse

[flyhalhl@gmail.co.]

Briggs & Stratton
17.5hp Intek IC
model 31C707-0154-E1

I bought this engine used and used it 3 seasons now. last year it became hard to start. turning the motor by hand past the compression stroke was difficult and thats where it would hang up when I tried top start it.
of the 5 times I started it this season it would only start 2 times on the first try. If I put my battery charger on it I can get it to start. Battery is testing at 12.8 volts and is charging close to 16 when its running.

I went to adjust the valves today. There was more oil then I expected in the valve cover. Maybe 1/2 a cup. The valves were very tight. No gap at all at top dead center. I re-gapped them. guy on you-tube working on the same engine said 6 thousandths on the top and 10 thousandths on the bottom. That's what I did. When I put it back together it did not start, it hung up in the same place as before in the compression stroke.

The motor was even harder to turn then before. almost impossible to turn it by hand.

What do I need to look at next?

 

[flyhalhl@gmail.co.]

About twice too much clearance. 3 to 4 thousanths more normal for these overhead valve engines. Valve adj controls the compression release. So valves open slightly before piston at TDC (max compression). Valves to loose (big gap) they release to much of compression so cylinder will not fire. And valves too tight, compression so high that starter does not have enough torque to rotate piston thru TDC/full compression.
These overhead valves are notorious for valve wear and not opening the valve to reduce compression when starting. When engine is running, piston moving too fast to reduce compression much.