Mower turns once then stops

[ThatBadMechanic]

My bad for not checking the engine IPL first before writing the reply
I shall go to bed without any dinner and stand in the naughty corner for an hour after removing my incorrect post.
If the engine has been running for a long time with zero valve clearance then there is a really good chance that the cam &/or follower has also worn excessively.
The valves are identical as is the cam grind
So the valves on each side should move the same distance in & out and open & close at the same positions of their respective cylinders
I put a run a masking tape around the flywheel & mark the opening & closing points with a sharpie against the side of the magneto
Left & right should be almost the same variations in the actual valve lash will vary the opening & closing times a little so it is "same" not identical .
You can go one step further and stick a timing disc to the top of the flywheel

I looked at the cam already, and yes it had some wear but it's by no means terrible. from everything I heard these engines are basically indestructible.

 

[bertsmobile1]

If you got the valve lash wrong and it is too big then this overcomes some if not all of the decompression at cranking speeds
The usual symptom is quick cranking with no plugs & unable to overcome compression plugs in
Usually a problem with OHV engines because the valve lash tends to open up where as on SV engines the valve lash tends to close down .

 

[ThatBadMechanic]

If you got the valve lash wrong and it is too big then this overcomes some if not all of the decompression at cranking speeds
The usual symptom is quick cranking with no plugs & unable to overcome compression plugs in
Usually a problem with OHV engines because the valve lash tends to open up where as on SV engines the valve lash tends to close down .

but it wouldn't make sense for the engine not to crank back on one side before any adjustment was made on the valves, the first time I reassembled the engine the valves were basically not touched, besides opening them up slightly to put cam back in place.

 

[StarTech]

Camshaft should had went back in without forcing any of the valves open.

 

[ThatBadMechanic]

Camshaft should had went back in without forcing any of the valves open.

View attachment 61241

I needed to open them manually since there was zero clearance and they were pressing onto the camshaft enough to not allow it to go into place while valves are completely closed. Perhaps there is a different way to put it into place without opening valves.

 

[StarTech]

Ah the worn valve and seat problem.

I got an idea the starter was the culpirt if everything was aligned properly. May have been worn bushings or a magnet that came loose. I have seen starters to bind under compression when they are worn out.

Anyway with the starter now fried (if I read correctly) a new one might resolve the problem.

 

[ThatBadMechanic]

Ah the worn valve and seat problem.

I got an idea the starter was the culpirt if everything was aligned properly. May have been worn bushings or a magnet that came loose. I have seen starters to bind under compression when they are worn out.

Anyway with the starter now fried (if I read correctly) a new one might resolve the problem.

Well, the starter gear is basically done for, I managed to get it to grab onto the flywheel, however it seems like I was wrong. the starter is fine however something is wrong with the right piston. I might take everything back off and check the piston rings to make sure they're fine. I didn't hone the cylinder walls either so I might aswell do that this time.

 

[Tinkerer200]

You are doing something I never did and would not recommend. Putting new rings in just one cylinder but that is not causing your problem. There must be the correct valve clearance on each valve when it is in the correct position to set valves as outlined previously. Don't recall that I ever installed a camshaft in these engines with the valves in place. When I did an engine, I did an engine, rings, valves, seals all at the same time and I have done a lot of them. Opposed 40 series, 42 series and 46 series, basially the same configuration of engines.

Walt Conner

 

[ThatBadMechanic]

You are doing something I never did and would not recommend. Putting new rings in just one cylinder but that is not causing your problem. There must be the correct valve clearance on each valve when it is in the correct position to set valves as outlined previously. Don't recall that I ever installed a camshaft in these engines with the valves in place. When I did an engine, I did an engine, rings, valves, seals all at the same time and I have done a lot of them. Opposed 40 series, 42 series and 46 series, basially the same configuration of engines.

Walt Conner

Oh no I've installed rings in both pistons, however the problem only occurs when the spark plug of one of the pistons is installed, I kind of gave up at this point and looking to buy a new mower sadly, I'm unsure what is causing it since I've set the valves correctly as far as I can tell.

 

[Walt 2002]

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