Machine wont start

You have a timing issue or your intake valve(s) are not closing.

What machine are you running? What engine?

I would do a compression test for starters.

Check for spark first; this can cause a carb backfire. Next, since it is so easy, I would pull the valve covers and see if you have a bent pushrod; I am willing to bet that is your problem. If not, check your valve clearances also, turn the engine by hand and make sure the valves are operating properly.

And easy on that starter, big fella! You're gonna burn it up.

To check spark, you can remove the plug and then reattach it to the plug wire then ground the plug to the engine and try to start it. Remove the other plug or wire too so the engine wont start.

The push rods are easy to check, just remove the two 10mm nuts on the aluminum (ohv) valve covers and pull them off. Sometimes you will find that push rod is just laying inside, which will be obvious to you. Usually they get bent to the point where they just come out of contact with the rocker arm/lifter.

Sometimes, the rocker arm bolt comes loose which will spit the pushrod out.

Just pull the valve covers and see what you find. As Ara said a compression check would be a good idea, but I am asuming you don't have a compression tester, so this visual inspection is the next best thing you can do.

There is no timing on these engines, really. They are timed when they are assembled; the crankshaft and camshaft have to be assembled with matching timing marks. So unless you completely tear the engine down and re-assmble it incorrectly, you cannot affect the timing.

Also, the ignition coils and magnets on the flywheel are set so you cannot do anything really to screw up the ignition timing either.

Pushrods are very cheap and easy to replace; so no, you will probably not need a new engine. However, I had a welder come in a couple of months ago with a Kohler engine and one of the rocker bolts came loose and the push rod ended up going through the plastic valve cover. I had to install a short block in this case because the lifter bore opening also was damaged in the process. If you replace them, just make sure you check and adjust the valve clearances to the proper specs.

His mechanic did a cylinder leakdown test and found that the piston rings in one cylinder were shot.

The rocker bolts have nothing to do with the timing, if you remove them, just make sure you torque them back down to the torque spec.

For future trouble shooting

The 4 cycles for your fourcycle engine are
1) Intake (air/fuel entering cylinder through intake valve)
2)Compression(fuel air mix compressing in cylinder)
3)Ignition or Power Stroke (compressed fuel sparking or igniting creating power stroke)
4) Exaust(allowing burnt ful to escape cylinder through exaust valve)

If you have fuel(spark plug is wet) intake should be fine
If not spray carb cleaner into carb if engine starts and runs for short time you have a intake problem, possible carb or valve check for compression.

If spark plug is wet yet not firing first replace plug make be fouled, that engine has a electronic ignition module built into the coil and very rarely go bad.

Exaust can be checked by compression.

Another thing no one has mentione could be flywheel key sheared which will effect timing, again rare to happen but possible.

If no compression a push rod may have come dislodged , just remove valve cover and check that they are in place.

My brother use to teach NAPA techs on how stuff works ... he use to say ..... "Who here knows about .... Suck, Squeeze, Bang and Blow" ..... always lightened up the crowd ....

1. Suck ... gotta suck in air & fuel
2 Squeeze .... gotta compress the fuel air mixture
3. Bang ... spark to make it go bang .... and
4. Blow ... gotta blow out (exhaust) the burned out gases.

you can remember it either way but they my bro taught it is prolly easier

Never heard that one! I like it!

haha

Hillbilly Tech School. No wonder the NAPA guys know so much.haha Can you say wannabies?