After overhauling GX140 completely, won't start

The GX honda engines have a punch timing mark on both the camshaft and the crankshaft gear. You may be confusing the timing setup on the GV series engines.

After replacing the spark plug it ran on starting fluid quite well!!

So I returned the fuel take and carb and then it started right up!!!

Then after a bit a turned off the choke.

Then let it run a while to see if it was stable.

But after about 2 minutes, it slowly started dying.

When it died, it refused to crank at all.

So I pulled the carb and gas tank off again.

And then I tried again with starting fluid. No Dice!!

So I checked compression. Good!

Then opened up the head and found that the bolt holding the rocker for the exhaust valve
worked itself very loose. IT was loose enough that it cannot open the exhaust valve.

That seems to explain why it was gradually dying...as the exhaust valve bolt was gradually unscrewing itself.

So I fixed that and tested the valve adjustments. All good now.

But now it still won't start.

So for grins, I checked the spark again. No spark!

What?? It's brand new spark plug.

But with the exhaust valve problem could it have "fouled" the spark plug?

I'm going to see about getting spark plug cleaner and also yet another spark plug.

I cannot imagine that the coils went bag already.

ILENGINE said:

The GX honda engines have a punch timing mark on both the camshaft and the crankshaft gear. You may be confusing the timing setup on the GV series engines.

Click to expand...

Thanks. I tried even with magnifying glass and couldn't find any mark on the crankshaft gear.

In any case, it ran great for a while now, so that seams to rule out timing issues.

Thanks again!!

So it doesn't have spark with the spark plug.

So I bought yet another spark plug and also a spark tester.

With spark tester, it sparks if setting the gap very small.

But if setting it similar to the plug, it won't spark.

And the brand new spark plug won't spark either.

This is a brand new $14 aftermarket ignition coil. Could it be
defective? Should I order to OEM one from Honda to get
a better spark?

In reading reviews on this ignition coil on eBay, people say it's not
an exact fit. They say it needs some extra washers to get it into the
right position. I recall feeling it sits lower than the old one.

The could explain why the spark is weaker since it's several millimeters
off the original center position. I will get some washers and try
adjusting it.

veryrealman said:

So it doesn't have spark with the spark plug.

So I bought yet another spark plug and also a spark tester.

With spark tester, it sparks if setting the gap very small.

But if setting it similar to the plug, it won't spark.

And the brand new spark plug won't spark either.

This is a brand new $14 aftermarket ignition coil. Could it be
defective? Should I order to OEM one from Honda to get
a better spark?

Click to expand...

I don't how to set that gap (wish I did) but can confirm that the gap between igniter/coil and flywheel is TINY, like less than a business card's thickness. Visually it would appear to be rubbing the flywheel.

Argh.

After adding some washers so that the coil rods move directly across the center of the magnet,

I got much better stronger spark for several pulls of the cord.

But then it got weaker. And weaker.

I looked at the OEM coil and noticed that it's not adjustable for the gap. It's an exact fit.

So maybe my air gap adjust moved after pulling it a few times. I'll check that.

deckeda said:

I don't how to set that gap (wish I did) but can confirm that the gap between igniter/coil and flywheel is TINY, like less than a business card's thickness. Visually it would appear to be rubbing the flywheel.

Click to expand...

veryrealman said:

Argh.

After adding some washers so that the coil rods move directly across the center of the magnet,

I got much better stronger spark for several pulls of the cord.

But then it got weaker. And weaker.

I looked at the OEM coil and noticed that it's not adjustable for the gap. It's an exact fit.

So maybe my air gap adjust moved after pulling it a few times. I'll check that.

Click to expand...

This is weird, you had to add washers to the existing design? And despite there being no way to adjust the gap, the gap could have widened? Does not compute.

Honda have many factories in China and source a lot of parts from China.
Honda have excellent quality control so reject sub standard parts
Guess what happens to the sub standard parts ?
They get sold at auction, bought by general trading companies then resold on line .
When buying aftermarket parts they must be branded, be packaged in a branded box from a company that has a real physical presence in your country.
I could list hundreds of cases where people have come in with a defective "brand new" aftermarket part.
Stihl ignitions are notorious for working when first installed then slowly fading away to nothing.
Get a new one from some one like Stens, Rotay, Prime Line for aftermarket guaranteed parts or real a real Honda one.

They have a chip in there which is sensitative to heat and several soldered joints which are also heat sensative to heat

If the coil has been touching the flywheel while running then it can get hot enough to go bad.

After reading this entire thread, I have one comment to make:
I believe that some time ago I read that Honda lawnmower engines' spark plugs fire on both the power and exhaust strokes.