Briggs engine kicks back when starting, runs rough, hard to start. But Ignition module, spark plug, flywheel key are fine?

[TylerFrankel1]

You're going to need to tap the holes anyway and don't buy HF tap and die set. They are lousy to say the least.

Self tapping screws can be made if you know how.

Good news. The mower I started this thread on, that had the fully sheared key, is now fixed and back with its owner. +40 bucks for me. It needed nothing but the flywheel key. I also sharpened the blade best I could and balanced it. (He needs to replace it after hitting all the stuff he has because it's dinged pretty bad, but he doesn't really care so I don't either). I changed the oil and put in fresh fuel. I put in the cleaned out air filter, it seemed good enough to use again after a good clean, and it starts on one pull. Runs great.

The other mower I had mentioned before that I said was also running rough has been my focus now. It is not going as well. (It's the one I posted a picture of with a semi-sheared key).

When I tried to be crafty and make my own puller, I ended up breaking a bolt head off, and a bolt got stuck in the flywheel. I just snapped it off at its base and thought nothing of it, until I tried to use my new harbor freight puller. Then I realized I needed that hole LOL. I drilled a new one beside it and used the harbor freight bolts included with the puller to self-tap. Surprisingly that worked. The pulley came off with a big pop. I think the semi sheared key was holding it abnormally tight. The flywheel looks ok, but I am nervous about having a new hole in it. I don't want it to explode. This is a mower from the free pile that I am trying to sell for profit. If I sell someone a grenade flywheel I might get in trouble. Anyway, it was filthy, so I cleaned the block really good, and reinstalled the flywheel with a new key. Gapped the ignition. Checked the plug. Cleaned the carb.
AAAnd it runs no better than before all of that. It's still better now that the blade is straight, but its not great. It isn't terrible though; The untrained ear wouldn't notice or care about the way it runs. But it's almost quieter than normal, a bit low on RPMS, and vibrates a bit. The oil was overfilled. I drained it a bit back to normal level. No change. Also, when I lift the mower off the ground, it makes a slight rattling noise from the engine somewhere. I don't know what that noise could be, because I had it torn down almost all the way and didn't see anything that would do that. I decided to take the head off and have a look around. Head bolt broke, there was one that was extremely tight on the bottom center. Valves are seating properly though, and cylinder walls look great. Not a crazy amount of carbon. Now I'm at a loss again, as to what the problem could be, just with a different mower this time. Maybe it's supposed to run this way? I also don't know what to do about the headbolt and the possibly dangerous flywheel. Although, I suppose that if the flywheel broke, it would have the shroud around it and probably wouldn't hurt anybody.
Any ideas? Thanks again!

Video of mower:

Side note. The front wheels are incredibly loose. Not the bolts, but the diameter of the wheel mount is way to big for axle. Either extremely worn or somebody put the wrong wheels on.

 

[ILENGINE]

On some of the mowers with the newer Susa cup type starter. The handle has enough slack that will cause the starter pawls to come out enough to hit the inside of the starter cup when a downward pressure is applied to the handle. that could be your noise.

 

[TylerFrankel1]

On some of the mowers with the newer Susa cup type starter. The handle has enough slack that will cause the starter pawls to come out enough to hit the inside of the starter cup when a downward pressure is applied to the handle. that could be your noise.

You know what I bet you're right. It does kinda sound like that's where the noise is from. So otherwise, it's pretty smooth but the engine of course still is running in a way I think ain't right. I't probably fine. Maybe I'll try runnin some seafoam through and adjusting the governor. Also the blade boss missing one of those little pieces may be an issue I need to address before I sell the mower. So I gotta check that, the wheels, flywheel, running rough, and a broken head bolt. These engines have like 8 bolts, if just one is broken, would it be a huge deal?

 

[ILENGINE]

Depending which bolt is broken could create bigger issues than others, but one missing bolt will always have the potential for a head gasket leak.

 

[bertsmobile1]

IF you have a compressor then use the air hammer with a pry bar.
The x thousand blows a minute do much better job than a smack from a 4 lb hammer and far less likely to end up with a hole in the crankcase.
I have had that tool for better than 20 years. it came as part of the " + free tool kit " with the compressor and until I started working on mowers only ever used it to chop off a couple of nuts.
Now it gets used daily & is just about worn out and the hammers are going rusty

 

[TylerFrankel1]

I do plan on getting some more tools in the near future - air hammer, pneumatic drill, compressor, torque wrench, tap/die set, new ratchet, maybe a welder one day, etc.

Anyway I drilled out the broken bolt yesterday to 5/16ths. I don't have a drill press, so it's not perfectly straight, but it should be good enough. The problem is, I do not know what to do now. I can't find any specs as to what the head bolt dimensions are, so I don't know what heli-coil kit to get. I considered trying to find a bigger bolt and tap some bigger threads and just use a bigger bolt too. But, I don't know a ton about how bolts/threads work, so I don't know what to look for. Any Ideas for this? Thanks!

 

[PTmowerMech]

I do plan on getting some more tools in the near future - air hammer, pneumatic drill, compressor, torque wrench, tap/die set, new ratchet, maybe a welder one day, etc.

Anyway I drilled out the broken bolt yesterday to 5/16ths. I don't have a drill press, so it's not perfectly straight, but it should be good enough. The problem is, I do not know what to do now. I can't find any specs as to what the head bolt dimensions are, so I don't know what heli-coil kit to get. I considered trying to find a bigger bolt and tap some bigger threads and just use a bigger bolt too. But, I don't know a ton about how bolts/threads work, so I don't know what to look for. Any Ideas for this? Thanks!

Take the drill bit you used to the parts store and tell them you need a heli coil set that will fit the hole you drilled with that bit. They'll probably just hand you what you need.

 

[Rivets]

If you are going to use a Heli-Coil and do it the right way, you can just guess at the drill size. Heli-Coils use a size specific drill to thread size. You need to purchase a kit which will include drill, tap, insertion tool and inserts. Using the wrong drill could easily lead to more problems.

 

[TylerFrankel1]

If you are going to use a Heli-Coil and do it the right way, you can just guess at the drill size. Heli-Coils use a size specific drill to thread size. You need to purchase a kit which will include drill, tap, insertion tool and inserts. Using the wrong drill could easily lead to more problems.

Well I finally bought a tap/die and a torque wrench.
Instead of Helicoil I went a lazier route and decided to just tap it with 3/8 threads and use a 3/8 bolt with a lock washer I bought at Home Depot. That worked but I was stupid and rounded off the bolt by using a metric socket. So now I have to get some of those special sockets that can take off rounded bolts, and start over. I also managed to break another bolt off when practicing with the torque wrench. I think someone overheated this engine and made the bolts brittle. I'll be drilling and tapping another hole I suppose!

I don't see any drawback to using 3/8 bolts except that they aren't the same size as the old ones so it's less convenient to work with anyway.

 

[TylerFrankel1]

I've also been a bit nervous about the flyhweel since I put a second hole in it. I don't think it would hurt anyone though since it's surrounded by the cooling shroud. I don't know though.