OutdoorKing Repair Forum Forums Repairs and Maintenance Questions on Engines Questions On Honda Engines HONDA GCV160 Engine blowing smoke.

Hello,
This engine came to me on a Big bob 21� base that was trashed.
HONDA GCV160 GJE-1925845
The engine started and ran fine, but it was blowing smoke, black from memory.
This is the first one of these engines I have ever had, so planned to use it as a learning tool.
Because of the work it had done I pulled the engine apart assuming worn rings.
An afterthought was that it could have been stuck on choke or set too rich.
This was the hardest flywheel for me to remove to date, I couldn�t use my usual steel plates. From the manual it showed 2 cut-outs on the flywheel saying �PULLER�.
So I now finally have a large 2 leg puller. After many days of spraying, tapping & tightening it eventually exploded off the shaft. I didn�t want to use heat as the top seal was right there.
This is the engine and the condition of the piston and bore showing scratches behind the ring grooves.








Here are the new & old ring end gap measurements.
I am considering using a new set of GXV140 rings.
Please see image of the comparison.


The only size that doesn�t fit the service limit window is the GXV140 second ring, its gap is too small (see image of 2nd ring in the bore)

NOTE: I wet the carbon with oil in the image above.

Any opinion as always is much appreciated.
Mark

Hi Mark, i'm no expert here on the Honda stuff but i think your afterthought guess around the carby would have been my first stop also.
Never the less, like you say you will use this one as a learning curve.

Thanks bigted,
I intend to line the cylinder with cardboard & clean the carbon from head with a wire brush on a drill extension & my bearing scraper.
Then lap & service the valves.
Then give the cylinder a hone.

After honing, the new GXV140 ring gaps should be larger.

My assessment of old rings is:
-top ring worn to the extreme of its service limit.
-second ring you can drive a train through.
-oil ring worn just outside its limit.

As you say, Mark, it is an opportunity to become familiar with the OHC Honda engines, which may make it worthwhile overhauling it provided you don't spend much on parts.

Working from the ring gaps alone, the wear is perhaps about as bad as on an ex-contractor pushrod Honda that has been scrapped because it has just started to blow oil smoke. Typically I'd expect to find 0.0020 - 0.0022" of bore wear on a healthy engine to get the results you've got - but there would not be any sign of striations to the bore or piston. Because of this it may be that your engine has a quite different problem from normal wear. The first possibility to consider is that it may have been operating for a long time running extremely rich, which washes the oil film from the cylinder, and is likely to result in bore striations like yours, and a larger than usual amount of bore wear. Alternatively of course it may just have been run for years without an oil change, resulting in a lot of oil contamination. The striations on the piston and bore are characteristic of either lubrication failure or contaminated lubricant. You should know which it was by now, from the condition the oil was in: was it extremely black and filled with swarf, or did it have the nasty acidic smell of oil with petrol in it?

The much higher wear on the second ring than on the top ring is characteristic of Honda ring sets: the top ring is chromed, while the second ring is not only not chromed, it is tapered to act as an oil scraper, resulting in relatively rapid wear until the taper feature wears off it. On the older engines, the oil ring was a one-piece cast iron affair, not chromed, and it wore nearly as quickly as the second ring. In recent years they have had automotive-style oil rings: a pair of chromed, steel-rail rings with an expander/spacer in between. This has given a substantially reduced oil ring wear rate, but made no difference to the wear rate of the second ring.

If you can't find any tendency for the striations on the piston to catch a fingernail dragged around it, I'd say you can re-use it in a 4 stroke like that, but not in a 2 stroke, and not in a customer's engine. However I would want to know the bore size and piston size, compared with standard sizes.

I can't immediately think of a cause of the rich running other than obstructed air cleaner, choke not opening properly, float bowl flooding, or amateur interference with the internal parts of the carburetor.

Hello Grumpy,
I have had this one apart for a while now and do remember the throttle control was tied in one position with wire.
Plus the filter was choked.
The oil does have a smell to it.

The scratches in the bore look worse than they are, it will hone up alright.
I will do some measuring of the bore & piston against the maintenance standards.
Thanks much for your thoughts.

It is all a question of what you are trying to achieve, Mark. I've thrown away Honda engine parts that were well within maintenance standards, because I'd rather have near-new ones, and for a modest cost compared with new ones, you can probably buy a bucket of parts somewhere. People seem strangely prone to taking engines to pieces, losing or destroying a few parts in the process, having no idea what to do next, and shovelling the mess into a bucket and selling it. Of course they will probably claim it's a complete engine, which it won't be, but it may be an excellent resource for parts in good condition - and you can look at the parts before you buy the bucketful. On the other hand I had another very worn Honda - within service limits - that I just re-ringed and put back together and found it had a big-end knock at idle. By my standards the whole thing was worn out, so I just kept all the bolt-on bits (especially air cleaner, starter, carburetor, and ignition module of course, but also all the fasteners, most of which seem to be missing from bucket engines) and scrapped the rest. Since that experience I no longer re-use a block with more than about 0.0025" bore wear, or a crankshaft with more than 0.0005" of crankpin wear. This leads to nice quiet Hondas that I enjoy using - and I think other people would enjoy them too.

I will try and extend the life of this engine, the best I can with what I have.

Will take the engine to work to get the piston & bore measured accurately. Best I can get is 64 mm, for both.

I have done the cylinder honing & the GXV140 second ring end gap was 0.009" now 0.011".
Valves were in good shape, only need a little lapping.

I also checked the GXV140 rings, side clearance in the piston grooves, which are OK.
Will get back onto it in a few days.

It isn't really practical to work out why Honda uses a different ring design in the GCV160 compared with the GXV140. In the case of a modern car, making the substitution blindly would be a bad idea because of problems like ring flutter which may occur at a specific engine speed. For a small light-duty mower engine, which runs at quite modest speeds and accumulates relatively few hours under load, some minor ring malfunctions might be insignificant in practice. So, now that you have volunteered to be a guinea pig Mark, you may find out on behalf of all of us, whether the substitute rings last as long as rings of the correct design. That is if you keep the mower yourself and accumulate a couple of hundred hours of use of it, of course.

Points all noted Grumpy,
Love your post #62854, all those points where not at the forefront of my mind, they are now though.

I'm certainly not advising others to follow my lead, just thought I would share this repair with other forum readers. Plus I see the embodied energy in an item like this & like to try and save it, but it has to be economical for me to do it.





The fella's in fitting couldn't find their internal micrometre, I'm going to have to get one of those.
With the ring gaps measured, I'm sure it will be fine. If I didn't have some level of confidence I wouldn't move forward.

This is an interesting engine design, very different from what I have seen before.

With assembly: The piston rings slide in by hand with a gentle push of a screw driver here and there. The cylinder having a taper lead in makes it easier.
The piston & con rod are marked well for its orientation.
Crank has an arrow and cylinder has a mark to align, cam has the 2 marks underneath to line up, then fit the belt.

Not sure about the sealant under the valve cover, I would like to see a cork gasket there, especially for a cover that comes on & off for periodic servicing.

I am chipping away at it, will let you know how it works out.

Please keep us informed as you go, Mark - like several of your previous threads, I think this one will be useful to quite a few people in the future.

I have run this engine unloaded, yesterday.
Today I did some mowing, progressively loading the engine & increasing its speed.
No smoke, all sounds and feels ok.
Has a bit of a surge, I may have to look at the carb again.



Not a big fan of bar blades, but its the only 21" option I had.
Surge could be to do with the bar blade.
I will order a new universal blade plate for it, the old one was fractured in numerous places, not the first time I have seen this.

If the hunting is at or near idle speed, you will need to pay particular attention to the idle jet. On the GCV engines, unlike the GXV ones, the idle jet is a pressed-in metal part that has to be cleaned in position in the carburetor. This is not an easy thing to do with a 0.3 mm hole buried deeply down in a coal mine, but it can be done with a jet drill bit and a lot of care.

Don't forget to check the condition of the gaskets on each side of the carburetor insulator, which are a standard source of air leakage on Hondas unless you replace them each time you remove the carburetor.

Other than that, I suggest you look closely at the emulsifier, which is prone to gum formation on Hondas, and it also can be difficult to dismantle due to the gum sticking the nozzle (venturi) end of the emulsifier to the carburetor body. Remember, you need to be able to put the correct size of jet drill bit through every one of those lateral holes. Note that some emulsifiers have two different hole sizes.

I have no respect for bar blades: they bend crankshafts, damage bases, cut poorly, and give a weak draft into the catcher. The best cure (on Hondas anyway) is to get a proper blade plate from a defunct Honda and fit four new good-quality blades to it. I did that on my favourite Honda (an ancient HR194 from soon after production began in 1983) a couple of years ago, and completely transformed the beast. Now if only I'd done it thirty years sooner, and if Honda had given the machine a bigger grass chute.

Yes Grumpy, the idle jet, I will investigate and do some more cleaning and let all know the outcome, cheers.

I managed to get the 0.3 mm jet drill through the idle jet hole, with just the air cleaner box removed.

The anti surge spring was rubbing a bit on the breather tube.

I also missed tightening the governor bracket.

The result is, it is running alot better, seems to have the slightest surge when running a full speed, certainly OK to use. I have done a fair bit of mowing with it and enjoy using it. Itstarts easily and idles smoothly. They are good choice of mower, powerful with a wide cut.

I have spent a fair bit of time rebuilding the engine and repairing the base, not sure if it was all worth it, for an engine that will last, I'm not sure how long.

It sounds as if it may still be a bit lean at full speed, which I suspect will be the main jet still having a small amount of gum in it. You could fix it if you went over the systems again. From what I've seen of them they are capable of running as well as a pushrod Honda, but probably not for as long, and they seem a bit more fragile, especially if you let the grass build up in the cylinder head fins. The cam belt also may give a little trouble, which is no big deal unless you have to replace it, which requires splitting the crankcase. Realistically I suppose they are a fairly good suburban mower, but I think I'd rather have a chonda if I could find one with a decent base.

Digging up an old thread here, got a relatively new GCV160 i picked up. It smoked a little and ran rough, i had hoped sorting the carb would resolve both issues. Wrong it's obviously not run right for a long time, and the fuel wash has absolutely shot the rings. Oil ring gaps are 0.026" top and second are well over 0.05", it's laughable how thin they are worn down. Good news is the bore and piston look actually look good next to no scoring at all. Tried to use the GXV140 rings, gaps were roughly 0.011 and 0.010 so similar wear to this engine however as i was about to file the 2nd ring gap i noticed the rings in this GCV160 are only 1.0mm wide not 1.5 like early GCV160/135 and GXV140. Does anyone know where to get the correct rings cheap or know of another alternative?

Anyone?

There is only 40+ GCV160 models out there. Will the complete info for look up.

Example of numbers> GCV160A S1M VIN# GJAEA-1000001

Sorry for the delay the number is GJAPA-1188330 N2U

GCV160A0 N2U based on the info given.

Based on the serial number your rings should be 13010-Z0L-014 STD Bore and the Piston would be 13010-Z2A-010. No oversized rings or piston listed for this engine.