OutdoorKing Repair Forum Forums Restoring, Customising and Modifying Tech Talk HONDA GXV140 self propelled.

I have honed the bore with the spring set on the hone at its lightest setting.
I honed it only until I couldn't feel the rust marks anymore, it is all smooth now.
I tried for a 30 degree cross hatch.
My hone with balls on it wouldn't fit, it was too large.
I have remeasured the bore with my internal calipers and transferring the measurement to verniers, best I can measure is 64mm.

It was 64 mm (2.520") when it left the factory, Mark. Given the minimal ring gap, it probably isn't much more now - it just didn't live to do much work I suppose.

The crankpin is the main worry at present. I'd linish it with long strips of whatever you use (cloth backed emery, or wet and dry) of about 400 grit. Just pull it back and forth like a shoe-shine rag.

Grumpy I will do some more linishing on the crankpin. I have found rings and am still sourcing a con rod. Thanks.

I have started on the frame today.



I normally fix the cracks and holes with fibreglass body filler.

That base is in poor condition, as I'm sure you know. I would throw it away. However the mission here is to fix the engine.

Ensure that the crankpin ends up round. You need to measure it to a ten thousandth of an inch at frequent intervals, and don't linish the smallest parts. Also remember that round does not just mean the same diameter everywhere, it also means having a single center.

I think I'd re-use the original rings, but that is up to you of course. My efforts to re-use piston rings have not been uniformly successful. Remember to put the rings in the right way up - that is crucial. Incidentally, the supplier in Thailand I have used offers gasket kits that include the connecting rod. I can't access ebay at present or I'd give you a link.

Hello, after some more work the pin now measures 25.965mm or 1.0222".


I cant feel any grooves with my fingernail.

Specification for a new crankshaft is 1.022-1.023, so that is within the new-shaft range. My best second-hand crankshaft measures 1.0225", and it runs just like a new one.

You've effectively lost some surface area, which will slightly increase the wear rate. I can't tell which way up the crank is in the picture, but it looks as if the damage is concentrated on the top of the pin, 20-30 degrees past TDC, right where the maximum load occurs. That is unfortunate, but to be expected since it was that pressure that caused it to spall in the first place. My guess is that it will run as well as my best one, but may not last as long. On the other hand, an OHV Honda that is serviced properly and regularly lasts so long that no one but a contractor is likely to live long enough to find out.

I noticed you can get under sized con rods, I was wondering if anyone has tried this, to close the gap on a worn crank pin.

Where I'm at with this so far: base is repaired.


I haven't had anything to do with these gearboxes, it is the 2 speed type.
When I opened it up the gear oil was lost on top of the bench, I was expecting to find grease inside.



There is no fill hole for the oil, so I will fill one half and seal it up, I plan to use gearbox oil.

That illustration is for the HR194 SXA, which has the 4 hp engine, but I suspect it is the same transmission you have. Note that EP90 oil is specified.

Thanks again Grumpy, the diagram was very helpful.
All the gearing looked OK.
130ml of gear oil was the deeper dished half filled to the brim.

I didn't notice the marks to align on the selector shafts when I pulled it apart, so they are lined up now.

I have it all back together and it all turns freely with no meshing.

I have reassembled the base.

I cant order the engine parts I want until the new year, so I will service the carby and starter and then this mower will be awaiting parts.

To answer a question you asked several posts ago and I missed, yes you could have the crankshaft big-end journal reground to a smaller size, but I think the cost would be more than buying three or four ex-contractor mowers, most of which would have good crankshafts. In the days when car crankshaft regrinding was commonplace, the experts told me that it was seldom done to anything approaching original equipment standards. The same was true of reboring cylinders.

Servicing the carburetor properly will take a couple of hours, so it is convenient to do it now, when it is not holding anything up. Bear in mind that the GXV140 is particularly prone (compared with other GXV engines) to developing gum deposits in the main jet and the emulsifier (including the tiny holes in the emulsifier). More often than not the emulsifier is glued into the aluminium body of the carburetor by hard gum. Remember, soak it out, don't try to force it out. And if you feel you really need to remove the pilot (idle mixture) screw, I suggest that you send me a PM. It is not appropriate to post about it in a thread.

Excellent work mark,very informative thread..

Thanks Chris, first time stripping one of these ,I am treading carefully.
Grumpy has been a great help :-)
I have been soaking and working on the carby, the emulsifier is out after a soak in some cleaner, it is not the best, I think it may be OK, if not I can source another one.
I have some parts now, so I will start to reassemble this engine before my retention span fades.
The rings are marked (top STD, Y STD)

You probably know this Mark, but the rows of tiny holes in the emulsifier should be checked individually. My way to do that is, after treating with carb cleaner and blowing out with compressed air, I push the correct size of jet drill bit through every hole in turn. I do the same thing with the main jet of course, and the idle jet ("Pilot Jet" - black plastic item, directly under the idle speed screw). I don't necessarily remove the idle mixture screw ("Pilot Screw"), if carb cleaner squirts out from the tiny hole near the throttle butterfly.

If that set you have is the rings-and-gaskets kit from Thailand, I don't think the rings will be chromed. I've used the Thailand unchromed rings (which probably come from China) and they worked fine, but after 6 hours use I replaced them with chromed ones just so I'd feel better about the repair job. The unchromed ones should last about as long as they do in a side valve Briggs, which would satisfy nearly all private users. (Original Honda GX/GXV engines have chromed top rings, though only the late production ones had chromed, steel rail oil rings. The older ones have plain cast iron oil rings, which wear out after say, 3 years of contractor service. Chromed steel rail oil rings should last considerably longer.)

Yes Grumpy, the emulsifier holes where blocked up. I have some fine bread tie wire I use to clear them, not ideal I know.

The kit I got was from Thailand.
I have been doing fencing and made some time to start putting this back together.
I have fitted the new conrod and rings.
I also checked the breather cavity and replaced that gasket.

Things I have done: fitted rings, oil ring is obvious, the ring marked (Y) I put as the second ring, the ring marked (T) I put as the top compression ring. All marking facing up as you look at the crown. I spaced the gaps 120 deg apart.
Fitting the conrod was not difficult, 2 circlips and the gudgeon pin came out easy.
I oiled the crankshaft bearing and all mating surfaces.
I made sure not to forget the black plastic pipe (not sure of its role, drain or pickup?)
The arrow on the piston crown is facing the push rods.
also aligned the timing mark on the camshaft with my scribed mark on the crankshaft gear.
All seems to be turning over as expected.
I will fit the oil pan tomorrow with its new gasket.
Not sure what the o rings in the gasket kit are for?

That black plastic pipe in the crankcase is called the "oil defense pipe":


Its purpose is to keep oil slung off by the rotating parts, from going into the breather drain hole (which is after the PCV valve, so it would end up going through the rubber breather hose into the air cleaner). Don't put it on facing the wrong way, or it will pick up oil instead of draining it.

I tend to bump that pipe occasionally, and actually knocked one off once, but it clipped right back on, undamaged. It is soft plastic.

I haven't used a gasket kit, and I'm not aware of what the O rings are for either.

Did you put the connecting rod on the right way around (marks for matching the cap to the rod should be visible, facing toward the crankcase cover opening)? And yes, the arrow on the piston top faces the pushrod cavity.

Are you sure you've seated the circlips properly? They'll come out and do evil things to the bore if you haven't.

I don't recall the second ring having a Y on top, I thought I recalled it had a T like the top ring. The T means top of the ring, not top ring. You can identify the second ring if you look at it carefully, it is tapered to act as an oil scraper:

The pipe makes sense now, I found that mine only fits one way.

The con rod is the right way, with the larger side inline with the arrow on the piston.

I measured both rings with the micrometre, width and height and also compared them with the old ones.
I found the one marked (T), slightly larger the one marked (Y).
So it is installed as the compression ring.
I looked for the taper, I didn't notice it, both looked square to me.

I haven't tried to fit the oil defense pipe backwards, I just carefully install it the right way around. I agree the offset connecting rod installs so that you put the cap on from the left side.

You didn't say anything about seating the gudgeon pin circlips. I find it needs careful attention. I put them in by gripping the tang on the end of the circlip (in projects radially inward) in long-nose pliers, with the tang pointing upward and the round part extending to the left from the tang. Then I place the part of the circlip closest to the tang in the groove, and twist the tang anti-clockwise. This contracts the round part so it will slip in. When it is in all the way around, I keep twisting the tang anticlockwise until I've verified that it will rotate fairly easily, sliding in the groove. Just pushing the clip in doesn't seat it, but rotating it that way does - plus you can feel it get much easier to rotate, once it is properly seated.

I haven't seen your piston rings, and they are not original Honda so they may follow a different design. If the second ring is not tapered, it will not serve much of a purpose. However I agree that there is a convention that if a ring is marked, it will be on the upper side.

I have pulled it apart again.
I put a positive spin on it by calling it practice.
I thought it was important to recheck everything.

The gudgeon pin clips are rotating in their grooves.
One of the rings is actually marked TOP not T. My over sight.
They are also different colours, the TOP ring is light grey. Don't know if you can pick that up in this image.

The old top ring is chromed and unmarked.
The old second ring is marked O.

None of these rings seem to be tapered.

I'm glad you checked those circlips - having one pop out is a very nasty failure mode, and I like to double or triple check them.

Honda's top ring is radiused on both top and bottom edges, it doesn't have a top. IIRC, I haven't seen a top marking on their original equipment rings. The "TOP" on the lighter coloured replacement ring might signify that it is the top ring. I don't like that ring: it seems to have burrs on the top and bottom surfaces at the ring gap. That isn't the kind of finish you get from Honda. If it were me, and I could feel the burrs with a finger-tip, I'd remove them carefully with a light touch of a needle file, then clean the swarf off. However you must hold the needle file flat along the top and bottom surfaces of the ring - don't just file it or you'll chamfer the edges rather than remove the burrs. They should clean up with one stroke, just a few centimetres of total movement of the file, with light fingertip contact pressure. There shouldn't be noticeable file marks on the top and bottom surfaces, just a sort of dull look, except where the burr has been.

Just wanted to check the timing before going any further.
I have some images at TDC.
Magnets just passing magneto, piston at TDC.
Mark on the flywheel is inline with the rear post, I thought this mark should line up with one of the magneto posts?
I can find it, I will keep looking.