Mower turns once then stops

[Walt 2002]

Actually sounds to me like too much clearance on right Intake valve. It is possible that the Intake camshaft valve cam lobe is worn excessively causing it to not release compression, but these are one pc forged camshaft and in working on dozens of these, I have never found one worn to the point of causing problems. You can check the valve action against the left cylinder, should be just slight additional Intake valve closing movement as piston nears TDC on compression stroke.
Walt Conner

 

[ThatBadMechanic]

You did clean any carbon from the cylinder head? IF you just want to get the engine running and not have to buy a different mower, install two head gaskets on the right cylinder. This will lower the compression, perhaps enough for engine to spin over and start. Not something I would do, I would find the problem but something I have heard of being done.
Walt Conner

I'll try to do this tomorrow!

 

[unkwnmike]

Hey everyone I have a 20 hp Briggs engine (model 460707-2278-E1). It's a really old engine that had bad compression on one of the cylinders. I took it apart 3 weeks ago in hopes of changing piston rings, after installing the new piston rings and putting it back together I tried to crank it and it would turn once and then stop if the spark plug is on. if the spark plug isn't in then it would continue to turn as normal. I looked up the issue and found out that it's likely an issue with the valves being out of adjustment. So I took the valves out, cleaned them up, and did my very best to get them back into spec. then I reseated them and used grinding compound etc etc. I put everything back together and the issue remains. I finally decided to take a look at the camshaft to make sure it was timed correctly today, and all was good. Put everything back together after cleaning it again, and still... the issue remains, I'm worried that this might be a starter issue however it doesn't make sense since when I took everything apart it was functioning fine. So my question is: are piston rings the cause of my issues? or is the starter at fault, since compression on both sides of the engine jumped up quite a lot after re-seating the valves.

I had the same issue with my 17.5 briggs it turned out to be the moon key on the crank that holds the grear in place. the key would get stuck on the counter weight leakage. I trimed key back, reassembled fixed the problem