Your compression is good.

I think you may have two problems. My guess about the oil in the air cleaner chamber is that it has a blown head gasket, very common with these engines. Is it smoking? There will typically be a thin line in the head gasket, usually on the cylinder block side, from the combustion chamber to the push rod galley. I would not have thought you would have that much compression though unless it is just starting to leak.

The noise from inside the engine - again, my guess is that bearings are worn out in the counter balance ass'y and or the eccentric that the counter balance weights run on is worn. These are a part of the crankshaft and are not replaceable. The bearings in the counter are not replaceable either and the cost of new counter weight ass'y is prohibitive. This usually is caused by not changing the oil often enough.

Walt Conner

Probably not the problem, but I'd pull the valve cover and look for something wrong with the valve train. The price is right!
I'm thinking that maybe something is messed up there. That could allow the engine to seemingly run pretty decent if NOT under load.

Hi guys, thanks for the replies. I found the tractor section after posting in the lawn mower forum (sorry!). I have a feeling Walt is right as it not only clangs, but jerks everytime the crankshaft goes around.

But I am going to have a look at the valves just for the heck of it...just in case. Do you guys think a sheared flywheel key is a possibility?

It may be a "possibility", but I can't imagine it would have anything to do with your problem. If it was firing early enough to cause a severe noise, I couldn't imagine it being able to start. It would just kick back and possibly damage the starter motor.

Well, I pulled the valve cover off tonight and found that the end cap on the exhaust valve stem had popped off. I snapped a couple pictures but it was dark and they don't show much. I'll take some pics during the day tomorrow.

Couple questions:
What holds that end piece onto the valve stem?
Why would it have popped off?...excessive clearance?

Any suggestions on what I should do next?

Go to the Briggs site at the link and download the IPL for your engine.
That way we can be sure we are using the same terminology.

Here is a link that might be useful: Briggs IPL

Ok, so I checked the IPL for my engine. The part that popped off is the Valve Cap. It goes right onto the very end of the valve stem. Its reference # 238 (on page 3) on the IPL which can be seen here:
http://www.briggsandstratton.com/pdf/illustrated_parts_list/100%5CMS0148.pdf

Should I just pop that sucker back on and adjust the rocker clearance?

It is very hard to imagine the cap coming off the valve while the engine is running and not having an extreme affect on the engine running if it would run at all. I am not sure but what the thickness of that valve cap would be such that it would exceed the depth of the indention in the rocker arm, which holds the push rod in place, letting the push rod fall out and rocker arm dislocate. I would come nearing thinking that it was dislodged when someone was working on the valves and left out when the valve was adjusted.

Also, a dislodged valve cap is not going to cause the engine to "makes an awful clanging noise from the engine." It would be noisy of course.

Sure, put the cap back on, adjust the valves and see what happens. (Don't try to "pop" it back in place) To answer your question, it is held in place by the close fit of the parts, not enough room for it to come out.

Walt Conner

Well now that I think of it, I guess the Exhaust Valve could have stuck creating enough space for the cap to come out then when the piston came up and bumped the open valve it might have jarred the cap off. The cap has the recess that fits snuggly over the valve stem and there is oil there which creates a, I don't know the right term, sort of tension so the cap normally does not just fall off but a jar from the piston bumping the valve could knock it off.

And yah, you could depress the valve and re-install the cap but I still would want to adjust both valves.

You might want to think about adding some top cylinder lube such as Marvel Mystery Oil to you gas just in case the valves are wanting to stick.

I have detailed instructions on adjusting the valves IF you need or want them.

Walt Conner
wconner5 at verizon dot net (put in proper format)

Wow, this thing starts right up and runs fantastic now. The rocker arm stud had either vibrated loose or the previous owner messed with it. The exhaust valve had like 1/4" clearance. It was making a REALLY loud rapping noise. Anyhow, nothing appeared damaged. I adjusted the valves (special thanks to Walt) to spec and it fired right up and runs fantastic now.

Think I'll check the valve clearance on my Honda push mower now. Does anybody know the spec on that? Its a Honda HR214 SX.

On my OLD HR215SXA, with the GXV 140 engine it's
.006" IN
.008" EX

I'm pretty sure the GXV120 is the same.
I adjusted mine after about 12 years of use and one valve was only .001" loose. That was about 8 years ago. Guess I'll sheck them again in about 4 years:-)

Best a Special Thanks to Bill, I would have had you tearing the engine down.

I'll be curious to hear if the plug fouling continues and oil in Air Box.

Walt Conner

Absolutely, Bill you were right on the money, thanks mate. I ran the engine again today and the same noise came back. Thankfully, I do know the exact problem, which is the stud has vibrated loose again. But to be honest, I'm not real clear on the valve adjustment...

There's three separate pieces I'm dealing with. The rocker stud, the 10mm nut, and the torx screw. Should the stud be tightened down?.....and the clearance adjustment is made by turning the 10mm nut (without turning the stud)?.....and then when the correct clearance is found, tighten down the torx screw?

This is my first valve adjustment if you can't tell.

Bill,

The valve adjustment for the Honda, is this done 1/4" past tdc?

Use Loctite on the stud.

".and then when the correct clearance is found, tighten down the torx screw?"

Yah.

Walt Conner

Honda is TDC. No compression release.
(I thought I answered this yesterday????)