After overhauling GX140 completely, won't start

After overhauling HRM215 SXA (GX140 engine), won't start

Mine is a HRM215 SXA walk behind honda mower which is about 20 years old.

It ran fine but had oil leak that was getting worse. Plus it was getting increasingly difficult to start.

I took the engine entirely apart and replaced all the: gaskets, seals, rings.
Also replaced the ignition coils and carburetor.

It won't start. Here's what I tried so far:

1. checked the spark. Great spark!!!
2. Checked the compression. 105 PSI
3. Checked the fuel supply. There's plenty in the bulb of the new carburetor.
4. Tried opening the choke and spraying starting fluid into the carburetor.
4. A tech suggested it might be something in the head.
So I pulled the head off and discovered the valves were swapped.
So I corrected that
Again, I checked the spark, the compression, and still won't start.

By won't start,I mean:
The engine turns very easy now by pulling the cord (I cleaned lot of carbon buildup inside the engine.)
But it doesn't sound like it's firing at all.

How can that be when it has spark, compression and fuel?

I don't get it.

Any ideas?

An idea just occurred to me. Could it bad gas? this gas was treated with sea foam last year.
When testing if gas was in the curburetor, it smelled like good gas, I think.
I want to hear any ideas. But I'm willing to empty the gas and try fresh gasoline.

Hmmm. Could be bad gas, I'd try fresh gas. Have you tried pulling the spark plug and squirting starting fluid directly into the cylinder?

Sounds like you've covered the bases on compression, spark and fuel.

Regards

Jeff

No. Not into the spark plug hole. I'm wondering if bad gas plus starting fluid will prevent it from cranking?
To find out, I'll turn off the gas to the carburetor valve (this new one has a valve!) and empty out the bowl.
Then I will try starting fluid again directly into the spark plug hole. If it cranks then I'll know it was the gas and
replace all the gas.

jp1961 said:

Hmmm. Could be bad gas, I'd try fresh gas. Have you tried pulling the spark plug and squirting starting fluid directly into the cylinder?

Sounds like you've covered the bases on compression, spark and fuel.

Regards

Jeff

Click to expand...

If that doesn't take care off it I would start looking into timing. Meaning either the timing marks on the camshaft, and crank not lined up, or sheared flywheel key.

Thank you for helping! I have a similar suspicion. Timing was tricky because...

...the cam gear has a timing mark but not the crank shaft.

So I took a lot of care and research to try to make sure the timing was correct.
Top dead center is pretty straightforward to have the piston at the very top of
the cylinder. Then I set the cam gear as the Youtube videos showed.

But honestly, it happens to fast to be sure but it does sound like the spark plug
is firing during the exhaust stroke.

The flywheel key is in great shape. But I think maybe I should open up the
engine and rotate the crank shaft 180 degress so that the flywheels spark
happens on the other stroke.

Is there any way to check the timing in relation to the fly wheel magneto
without opening up the engine?

For example, it seems like if I line up the fly wheel megneto with the ignition coil
and then look at which valve opens next, it could show me that it's firing on the
exhaust stroke or the intake stroke, right?

QUOTE=ILENGINE;268491]If that doesn't take care off it I would start looking into timing. Meaning either the timing marks on the camshaft, and crank not lined up, or sheared flywheel key.[/QUOTE]

I'm becoming convinced that the timing is the real problem for 2 reason.

1. I was unsure of the timing and it seems that either top dead center for the crank shaft was fine.
But now I realize that the crank shaft has one TDC that lines up with the mangneto to fire the spark.
So it is possible that it's backwards.

2. When I pull the cord, I DO hear the engine firing the fuel but it's weird that it gives ZERO power
to continue running on it's own. This is why I say that it feels like it's firing the fuel during the
exhaust stroke which just blows out the muffler.

For these reasons, I'm convinced that I need to pen it up and rotate the crank shaft 180 degrees.
But I'd like to think of how to be certain of this before opening it up as that will take a bit of time.

ILENGINE said:

If that doesn't take care off it I would start looking into timing. Meaning either the timing marks on the camshaft, and crank not lined up, or sheared flywheel key.

Click to expand...

veryrealman said:

Thank you for helping! I have a similar suspicion. Timing was tricky because...

Is there any way to check the timing in relation to the fly wheel magneto
without opening up the engine?

For example, it seems like if I line up the fly wheel megneto with the ignition coil
and then look at which valve opens next, it could show me that it's firing on the
exhaust stroke or the intake stroke, right?

Click to expand...

Peek into the spark plug hole. Presumably, the piston should be coming up to its top as the magneto approaches the coil, yes?

(but verify that the valves are also moving as expected during this time)

That makes sense. So I removed the pull cord, gas tank, spark plug, and valve cover.

So now I turn the flywheel by hand and watching the valves and using screw driver in to spark plug hole to feel for TDC vs BDC

What confuses me is that it seems the magneto passes the coil for both exhaust and compression strokes.
Some research shows that this is probably a "wasted spark" system. So if the timing is off. It's not simply
180 degrees.

So it's possible that I have the camshaft off timing by a gear or two (or three). So it's unclear how to check the
timing without any timing mark on the crank shaft. I'll do some more Youtube video searching.

deckeda said:

Peek into the spark plug hole. Presumably, the piston should be coming up to its top as the magneto approaches the coil, yes?

(but verify that the valves are also moving as expected during this time)

Click to expand...

Okay, I carefully inspected the timing of the valves and TDC, BDC etc.
It seems fine.

So I simplified the engine by removing just returning the pull cord.
This means it's missing: gas tank and carburetor.

So sprayed starting fluid directly into the intake (no carb).

And it fired up!!! and ran on it's on for several seconds.

But now it won't do that again?????

deckeda said:

Peek into the spark plug hole. Presumably, the piston should be coming up to its top as the magneto approaches the coil, yes?

(but verify that the valves are also moving as expected during this time)

Click to expand...