160cc Honda lawnmower won't fire

[BeaterofAincrad]

I'm trying to fix a 160cc Honda push mower for a client. I did a light "spring cleaning" on it about a month ago. Anyways they lent it to someone and when they got it back it wouldn't start so he brought it to me to see if I could fix it.

The first thing I noticed was that the blade was bent EXTREMELY badly, I haven't bent it back yet because I want to get it running first.

I cleaned the carb, still no luck.
I checked for spark, have it(blue).
Gas(good gas) is getting to the cylinder.
There was some carbon on the plug so I cleaned it up. I was getting a black liquid(gas/oil mix?) on the plug itself.
I looked inside the cylinder through the plug hole and noticed some carbon on the head and I can't remember if there was any on the walls.
I checked the flywheel key and it doesn't seem to be sheared.
I removed the OHV cover to see if anything was wrong in there and nothing seemed off, other than the valve lash was atleast .015. I didn't mess with it because I wasn't sure if the valve lash(of .004) was different for this engine
I checked oil level and it's good and while taking the OHV cover off it did NOT seem like there was gas in the oil.
I also attempted to reset the governor, but it didn't need it.

I will get one fire every now and then but it doesn't seem to try to continue.

At this point in my opinion it's either the valve lash, something I'm overlooking, or something I haven't experienced/heard of before. My father(not a mechanic but does have a good amount of knowledge/experience with small engines and such) doesn't think it's the valves(though he's never even considered messing with them on any small engine).

Any advice would be greatly appreciated. The picture wasn't taken from the best angle but here it is anyways.

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[Denny]

Reset the valve lash.

Denny

 

[landuse]

I would also reset the lash. If it doesn't help you can always revert back to what it was

 

[BeaterofAincrad]

K thx, I thought so too but I wanted to get other people's opinion first and I wasn't 100% sure if hitting something would effect the valve lash.


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[landuse]

K thx, I thought so too but I wanted to get other people's opinion first and I wasn't 100% sure if hitting something would effect the valve lash.


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In theory it shouldn't really, but you never know

 

[bob58o]

Hitting something = Bent Blade = sheared flywheel key.
Take off the flywheel and check.

You didn't sound sure that the flywheel key was intact. Be sure.
While there set the ignition coil gap and valve lash. I'd search the interweb for lash and coil gap specs for your engine.

 

[BeaterofAincrad]

Hitting something = Bent Blade = sheared flywheel key.
Take off the flywheel and check.

You didn't sound sure that the flywheel key was intact. Be sure.

Then set your lash as well. 0.003" should be fine.

Yeah, I looked and unless the key sheared extremely cleanly it looks good.

How might I go about removing the flywheel? I don't have a flywheel puller. I've done it in the past but I can't remember how.


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[bob58o]

People say to put the nut on the end of the threads. Leave the nut so that it is protecting the end of the shaft. While prying with something from behind the flywheel, whack the nut with a hammer and it should pop off.

I have had little success with this method and use a craftsman two jaw puller.

I also use an impact wrench to tighten the nut, so my flywheels might be a bit more stuck to the shaft than if I torqued to spec.

---------- Post added at 10:10 AM ---------- Previous post was at 10:08 AM ----------

https://www.youtube.com/watch?v=cc52RJ46di4

 

[BeaterofAincrad]

Thx, I'll have to try that later.


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[Whitetrashrocker]

My bets on the sheared key also. There's no way to bend that blade that bad with cousin some damage.

 

[BeaterofAincrad]

My first thought was the key too but its still intact

I reset the valve lash but couldn't find my "refurbished" feeler gauge so I used a piece of notebook paper. It seemed to help a little so I'm going to have to find it and set them right. I should also find the model number and refer to a chart I found for the correct lash.

Here's what it was, I had to screenshot a video because the lighting was bad.

Is it possible the belt for the valve rocker/cam(?) slipped and screwed up the timing? The gears are plastic.

I think I'm also going to try a new spark plug, I worked on a power wagon for this guy and it had spark but wouldn't start so I got a new plug and it started right up.

Maybe the people borrowing it got extremely lucky and didn't do damage to the engine but somehow fouled the plug, maybe a really small hairline crack in the insulator that's covered in carbon.

 

[Whitetrashrocker]

For as easy as it is to tear these engines down I'd at least take a look. And you just might have said the magic words. "Plastic gears"
That key is stronger than plastic is.

 

[BeaterofAincrad]

The cam gear still turns when I turn the flywheel and does its job, but I do agree with you. I think I'm just gonna try a new plug first for as cheap/easy as they are to install, I'll look around maybe I have an engine that uses the same one so I can test it.

Even though I charge much less I'd feel bad if I couldn't figure it out and get it fixed in the same amount of time money wise as it would be bringing it to a more experienced person/dealer who could get it done in 1 1/2 hours and charge +$100

EDIT:

Almost forgot, thanks for the advice and video bob! I had to place the socket over the nut because I started denting a grill that was on the flywheel(assuming to prevent mice from getting in there or protect the recoil from the flywheel). It came off after maybe about ten taps, it probably took me that long to get comfortable enough to give it a good whack though.

 

[BeaterofAincrad]

Idk why I assumed, but the cam gear isn't plastic. It was molded so maybe an aluminum alloy, it seemed harder than that though. Anyways it's not important now because aluminum doesn't break like plastic.

I got a new plug and reset the valve lash to the specifications for that model.

It still doesn't want to fire, it'll fire once and not try to continue maybe 3/5 pulls. Would it not fire if the head gasket was blow? Or would oil leak out if it was?


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[Whitetrashrocker]

How strong is the magnet in the flywheel. Has it lost it's umph?
Do you have a timing light?

I just had my lawn mower have a no start issue. I started with the fuel but it ended up being a bad coil.

 

[BeaterofAincrad]

The magnet will hold my ratchet if that's what you mean.

No I don't.

If the coil is bad will it still spark?


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[Whitetrashrocker]

I'm fishing for a weak/erratic spark.

3 things. Compression, O2, and fuel, at the right time.
One of them is off.

 

[BeaterofAincrad]

Now that I think about it the spark did seem a little erratic, I'll have to have someone pull for me and compare it to one that I know is good tomorrow.

Thx a lot.

 

[Randy H]

Looks like a crack in the pic.

 

[BeaterofAincrad]

You scared me for a sec, that's just the oil reflecting the light. I can assure you that it's not broken, I tried moving it and it did budge(given there was a thousands of play for tolerances).


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