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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...

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.

Thanks for this info!

But it turns out it was my bad. I still had the cutoff switch engaged at the handled bars.
So I get great spark now.

bertsmobile1 said:

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.

Click to expand...

Folks, after getting good spark, it still wouldn't start even with starting fluid.

So I checked the compression again and it's bad.

What actually happened was I spilled most of the oil from the engine by mistake
while the valve cover was off.

So when I ran it several minutes, it burned up the piston rings.

That's also why it gradually was dying. I did cut it off when realizing that.
So hopefully I killed it before anything else was damaged.

I ordered new rings that will arrive Thursday.

It seems that it was all ready and working perfectly after changing the spark
plug but the lack of oil and possibly the exhaust valve rocker coming loose
killed it again.

When the rings arrive, I'll try all this again.