Recent content by jdtm

I think "standoff voltage" would be more accurate than stress. From an electrical perspective the idea is that the insulation will be more likely to fail due to the need to withstand greater voltage. From your later comments, you seem to agree. Widening the gap increases the breakdown voltage...

For everyone's reference, here is the PET-4000 in action: I am curious. Would you describe how it would have caught this problem?

ANSWER In the first post, I described two test, one for ignition, and one for compression. The ignition test needs to be looked at carefully. Ignition test procedure: Remove the spark plug, hold the body of the plug against the cylinder head, and pull the recoil. Ignition test result: There...

This engine has a date code of 0702. I think flux capacitors are only used on newer models. Besides saying that many things were OK, I mentioned two tests. What does each of those tests *guarantee* to tell you and not tell you about the condition of the engine?

Maybe a bit closer in format to What's my Line?

No.

Probably not. I was originally thinking that I would give the game about a day. By now, I have explicitly stated that most of the parts were OK. There are not all that many things left to consider.

I was actually thinking some strange carburetor problem myself when it first happened and I did the initial tests I described. However, I could not come up with a reasonable scenario either, and as it turns out, the carburetor was OK. I was suspicious of the coil thinking an internal connection...

It is unrelated to the issue, but I use this mower as a cheap brush hog sometimes. After going through blade adapters on a routine basis, I made a two-part adapter that allows some motion when there is a hard impact. It is much easier on the internals, and I have never lost another blade adapter...

Now you are thinking out of the box, and that will be helpful. But no, the throttle was OK. HINT: One of my original tests would technically be called an asymmetric test. An asymmetric test will either find if something is OK or bad but not the opposite. For example if you look under your car...

The blade and blade adapter were OK. However, that is a reasonable guess. The standard flywheel on an engine made for a mower has very little inertia, so without the added intertia from the blade, starting would be difficult. Maybe it would not even start. I am unsure on that.

HINT: You are drawing more conclusions from the tests I described than they gave. Regarding ignition timing, there was no internal damage, change in the timing gear alignment, or damage to the flywheel key, so ignition timing did not change after the mower met the log.

I will give the answer tonight (assuming nobody guesses correctly before then) in case anyone else wants to venture a guess or ask diagnostic questions before then.

The recently-sharpened blade tried to split the log for me but did not have enough power behind it to do the job, similar to my experience below, although that was different piece of wood and the mower was OK after I was able to retrieve the blade.

The engine internals were all OK. There was no damage to the timing gears, piston, valvetrain, crankshaft, or connecting rod.