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I had to replace the oil slinger/governor in this engine. Did so. Made sure the timing was lined up when I put everything back together. New gasket. Put a brand new carburetor on. Adjusted the valves to specs and in turning everything seems to be moving correctly, rods were functioning etc not bent or anything. Did spark plug test and it is getting a spark. When I try to start this (I do have the air filter off so I can get to everything) the starter turns everything over but it never fires. I've put starter in and one time I got a pop but most of the time nothing. This mower did sit (in a garage) for 4 years and the solenoid was frozen but I went ahead and replaced the whole carburetor which came with one. Any ideas on something I am missing here? I appreciate any help someone might have. Thanks.

Engine needs Spark (at the right time) Fuel, and Compression... and correct valve timing.
i would check the flywheel key that is aligned perfect and not sheared.
Or if you have any starting fluid/carburetor cleaner, spray some into the intake through the carburetor, then try to start, if it starts then dies, probably a fuel issue, if it doesn't hit on carb spray through intake probably a spark timing issue.

Gas is fresh?

Some engines do not fire every time the piston comes to TDC. On these types of engines you must make certain that the spark occurs when both valves are closed. IOW, you must make sure the fire is on the compression stroke.

The common behavior that gives this condition away is that the engine will fire with the exhaust valve open, which (after many attempts) results in a "fart" type noise from the muffler.

Briggs 31P are wasted spark magneto version as is most Briggs small engines use on lawncare equipment. Once you get pass twins then things starts changing.

StarTech said:

Briggs 31P are wasted spark magneto version as is most Briggs small engines use on lawncare equipment. Once you get pass twins then things starts changing.

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Agreed. Most smaller, single cyl engines use wasted spark. Wasn't familiar with the quoted model number, but the OP seemed to be desperate.

Confucius say. If it worked before you changed oil slinger and govenor gear start there. Cam timing can cause that problem. Double check flywheel key. If it is good then spark timing is good. Double check valve lash and spark. Spray some starting fluid in the carb and try to start. If it doesn't try to start you have a compression issue probably due to cam timing. Or it is because it is thursday.

First thing I would do is recheck the valve clearance, before reopening to check the timing marks.

MODEL 310000 VERTICAL SERIES
Valve Clearance – Intake .003 - .005 in. (.08 - .13 mm)
Valve Clearance – Exhaust .005 - .007 in. (.13 - .18 mm)

The usual trouble shooting when there is a spark, the timing key looks good, the rockers are moving as they should, there is compression & the engine does not respond to fuel down the plug hole is to rotate the engine with a pencil down the plug hole and mark the spot where valves open & close on the flywheel AGAINST THE DEPARTURE SIDE LEG OF THE MAGNETO with relation to the position of the piston

Question here. Did you align both dots or did use the crankshaft keyway instead of the dot on the crank gear? So techs miss the crank gear timing dot and try to use the crankshaft key. Also I have seen a few 793880 cams with two dots. IF this is the case you want to align with the one that has through hole the web arm

Scrubcadet10 said:

Engine needs Spark (at the right time) Fuel, and Compression... and correct valve timing.
i would check the flywheel key that is aligned perfect and not sheared.
Or if you have any starting fluid/carburetor cleaner, spray some into the intake through the carburetor, then try to start, if it starts then dies, probably a fuel issue, if it doesn't hit on carb spray through intake probably a spark timing issue.

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Thank you. I'm a novice at this and probably should never had tried this but I figured what the heck. Still learning.

As with all learning you to have reference materials. In this case service manuals, notes, and even pictures along a experience help. It is basically like going to school except it is technical (trade) school.

Have you downloaded a copy of the Briggs Single Cylinder OHV service manual? It is a good guide but doesn't cover everything.

Here’s the manual Star is talking about. https://docs.google.com/open?id=0B6NaqjIxWV1ybEN0LWo3azl6OUU

JPJ-2020 said:

I had to replace the oil slinger/governor in this engine. Did so. Made sure the timing was lined up when I put everything back together. New gasket. Put a brand new carburetor on. Adjusted the valves to specs and in turning everything seems to be moving correctly, rods were functioning etc not bent or anything. Did spark plug test and it is getting a spark. When I try to start this (I do have the air filter off so I can get to everything) the starter turns everything over but it never fires. I've put starter in and one time I got a pop but most of the time nothing. This mower did sit (in a garage) for 4 years and the solenoid was frozen but I went ahead and replaced the whole carburetor which came with one. Any ideas on something I am missing here? I appreciate any help someone might have. Thanks.

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Hi, did you solve this problem?

StarTech said:

Question here. Did you align both dots or did use the crankshaft keyway instead of the dot on the crank gear? So techs miss the crank gear timing dot and try to use the crankshaft key. Also I have seen a few 793880 cams with two dots. IF this is the case you want to align with the one that has through hole the web arm

Click to expand...

Sorry I haven't been replying but am just now getting some time to revisit this. When I put the oil slinger/governor back in I put the crank gear and matched the timing dots as I saw in online videos. I'm positive that was done right. I had to buy a new gear because the other one had broken. I meticulously removed all the little shards out of there from the previous one that had a piece broken off it. Cleaned it out good. I put a new key in. Initially when I was trouble shooting this I removed the valve cover and saw that one of the rods had slipped off the valve lever(?). I inspected that rod and it appeared to be straight and not bent or anything. I replaced it all and did the adjustments to the gaps. Everything looks like it is moving properly. I was able to get some loud pops a few times when spraying carburetor cleaner into the carburetor. Initially I saw that the solenoid below the old carb was frozen from sitting. I do hear that "farting" sound someone referred to.

kevindixon said:

Hi, did you solve this problem?

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Have been away from this. Just now getting back to it. Have not solved yet. I'm pretty sure the timing is okay but I still cannot get this thing to turnover.

Rivets said:

Here’s the manual Star is talking about. https://docs.google.com/open?id=0B6NaqjIxWV1ybEN0LWo3azl6OUU

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Thanks. I'm going to review this and start on this again now that weather is nicer. I'll post any progress.