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F* lawnmowers. If you have some way of making grass (or mowable weeds!) grow in sandy soil, I wanna know.

Any idea how many RPMs "way over revving" is? I used to tune mine down to burn less gas (and oil!) but I read in this forum that splash-oiled engines should idle at 3600 for good lubrication.

I dunno crap but I'd think "headlights". The resistance of a headlight bulb is low enough to show continuity with ground, and a ground wire wouldn't be yellow. I friggin' hope not anyway.

You won't find crap. It's a plague with cars, especially older ones, but mowers don't have those leak sources. I suppose a PCV leak is possible in some cases, but in reality it's either the intake/block seal or the carburetor/intake seal. Or, 99%, it's the carburetor and not a vacuum leak...

If this were a car engine, I'd say it probably has a vacuum leak. That's less common with small engines, but I *have* seen it happen.

Just barely adequate - for a deuce-and-a-half cargo truck. DAAAANG!

Choke, throttle, vacuum.

Slomo, I'm staggered that you didn't say to look for crap buildup on the cooling fins...

Either it fires or it doesn't... under what conditions? A plug may fire consistently in open air, but not at all under compression. That's the whole point of Slomo's 1/4" gap test.

I found an article on Wikipedia (Paschen's Law) which says (in a very confusing way) that the breakdown voltage of an air gap is a function only of air density and gap length (specifically, the product thereof). So, if you are comparing the ability to get a spark (achieve breakdown voltage over...

Slomo told you long ago how to test your spark. You didn't bother. Now that it failed the test, you're still farting around. You whined about 5 (not totally irrelevant) posts hijacking your 200-post thread. You can't be bothered to find non-ethanol gas. You won't drop $30 on No-Reilly for a...

Technically, it's not the pressure, it's the density. Air is an insulator; hydrocarbons are even better insulators. Increase the density by 6x or 8x, and you increase the resistance the spark has to cross. It's more complicated than this, because vacuum is also an insulator, and the...

There once was a young wrench named Slomo Who gave good advice to some joker Whose spark was not bright And failed to ignite Now we can all say "Hetoljaso"

pure-gas.org. Use the website, not the app.

Lol, I hear you. License plates, siding, the metal panels of old computer towers... but I've used all of it up and I'm seriously considering actually *buying* sheet metal. Or I could just trim a little from the shed, it leaks already.

18 gauge?

This confirms what was said on another thread... just because you can see a spark or feel a jolt doesn't guarantee it's a good enough spark to fire the engine.

It ain't Yamaha or Honda.

What is the depth of the entire bolt hole? 20 mm?

Aye, there's the rub. I don't know what the compression ratio or combustion chamber pressure is, but that hole is close to the top where it will see the max pressure. At a rough guess, it will be subject to about 1000 lbs expulsive force. A 1/4" bolt would cut this by a third. A 3/16" bolt...

You are out of your Lawn Royalty mind. You can't hardly fix anything on a cycle without dismantling the entire machine. Even checking the oil can be a two-victim job.

Remember that when you put a bolt through there, it may push more metal particles into the combustion chamber. Also, if you can get to the rim of the hole with a rat tail file and chamfer it round, it will reduce stress and future carbon buildup. What I would worry about is, will combustion...

What for? That space will lower your compression by like 0.00001%.

and I thought this hole would be plugged with a bolt?

That cylinder looks pretty ragged. I can see texture on it with my glasses off. If you want to rebuild an engine to learn, I suggest finding one that will be serviceable. Hell, you can rebuild mine. Here's what will happen if you put a new piston/rings into that cylinder, no matter how well...

Did you replace the plug? I had this exact problem recently and the plug was bridged by carbon buried deep between the outer wall and inner insulator. I guess the insulator had a crack in it somewhere.

I tried that JB Weld extreme heat stuff on an exhaust pipe and it burned right off.

Air, fuel, spark, compression... TIMING. If the flywheel key is bent/broken but the flywheel hasn't shifted much, you get an advanced spark that causes raging idle speed but knocking at higher speeds. Let the flywheel shift a little further and it's no-start territory.

If the noise gets worse when the engine is hot and is reduced by using heavy oil additives, it is rod knock. Don't leave heavy oil additives in your crankcase unless you plan to just beat it to death.

NEVER start a motor immediately after tilting it. The oil is in the wrong place. If it HAD started, it would likely have blown up.

You may have no choice, but it's hard on an engine to live outdoors. Drain all gas out of it and clean the carbureter. I found a picture that makes this look like a bowl carbureter; my condolences. Keep the tank full as much as possible. It's "probably" safe to run automotive carb cleaner...

Yeah, that's about it. You could replace all the moving parts, but you could also get an old engine that hasn't been fried and rebuild that without taking a chance the block is ruined.

The OP (who seems to have given up on this thread) said the flywheel key was good.

Good luck finding a wiring diagram... what I don't get is why it starts at all, it's more forgiving than the Crapsman I just paid too much for. Anyway: just test the switch on the original seat to see what state the circuits should be in.

You are in the wrong time hemisphere and time zone, my friend. Ever been upside down under a dash at -30 (C) with the wind howling out of the north? Can't keep a hat on, too dicey to wear gloves. Soldering iron will still burn you so fast you can see fat boiling under your skin. But, in the...

Could be. In forty years of wrenching, I've seen one possible (unconfirmed) valve problem (other than valves bent by timing failure). But that's 99% car engines.

Sir, I have never attended a motor which did not already have excessive wear in the bore. I count myself lucky if the crankshaft is not bent.

Gumout.

I had one with a brand new diaphragm was installed with a wrinkle (and blade was upside down, not relevant here). Intake nozzle isn't always replace either though it should be. No run, no surprise.

"Torque to factory specs"... urrrhh... some years ago I had a torque wrench that didn't seem "quite right". I got a new one. I had been torquing critical suspension and steering bolts to a third of spec. On highway cars, not lawnmowers. FK ME. Never trust anyone.

Run some carb cleaner through it... and tell us what your elevation is.

Running too lean, probably a fuel supply problem. Counterintuitively, this can cause carbon buildup too, because bad mixture = incomplete combustion. For Gawd's sake, don't use Slime, it's worthless, let alone taste it. WTF????

That's a lot of wires for a seat switch. Use a tester to figure out which need to be shorted. If it's not evident, you might want to consider reinstalling the original seat, or returning the new seat.

ALSO: some Briggs coils have an interference with some Briggs air vanes. I just had to clip a bit off of an airvane to prevent runaway. The coil blocks the air vane, causing the governor to think the engine is about to stall and GIVE ME ALL THE GAS. See if the air vane has a full range of motion.

Briggs governors are crap. Sometimes you can make them work acceptably by stretching/shortening springs. My Ultimate Solution is a "throttle" (made from a generic automotive manual choke cable) that manipulates the throttle - not directly, but by changing tension on the spring that opens the...

If it will backfire but not start, it's the flywheel key, six days a week.

OH, HOLY SHIT I JUST THUNK OF THIS... don't turn the engine over! If you really did bust through the cylinder wall, there are probably metal fragments in the cylinder. Blow it out with all the compressed air you can buy with money. My last experience with Easy Out was in the Eighties. Sue me.

So this will be an engine in which compression is dependent on a carburetor mounting bolt in the cylinder wall... I would SO do that, and brag on it. My wife is laughing, but she doesn't have to make shit run. "Easy Out" is a damn lie. The only result I ever got from it was a broken "Easy...

Most common reason is crankcase blowby. On flathead engines, a blown head gasket won't cause any oil inhalation. Here's another weird reason: people deliberately oiling the filter. I've actually seen this recommended in an old (~1980 vintage) book. I just cleaned up a filter that was soaked...

JB Weld is my hero but it will not withstand the heat in a cylinder for ten seconds.