'83 1100E cylinder bores look machine sanded?

[eldevigo]

I have a new (to me) '83 1100E that I just yesterday got around to working on. I have a laundry list of maintenance items I intend to do, but yesterday I started with changing oil, filter, and spark plugs. It seems that all of these items had been done relatively recently by the PO, but I figured I'd finish them up anyway since i already had the parts ready.

While I had the plugs out I got in there with a bore scope, and I was surprised how rough the cylinder walls looked. There is some scoring, and some pitting that looks like it may have been a casting flaw in the cylinder jug, but most puzzling to me is that all four cylinders have a very dense and pretty regular scuff pattern that looks as if they'd been machine sanded after being bored, and then never polished.

Is this normal for an 83 1100E? It's hard to tell with the bore scope exactly how deep the marks are, but it's very distinctly different from my partner's 1980 2-cylinder small bore honda I was looking at a few weeks ago. There's two distinct biases to the scour lines, spiraling down the bore both clockwise and counter-clockwise.
What am I looking at? Is it a sign that someone did a hackjob trying to refinish or re-bore the cylinders? The sanding patterm is visible in all of the attached photo and was consistent across all cylinders.


Besides this sanding pattern, there are a few other signs of damage in here. There's some longitundinal scoring, which I assume is due to debris or a problem with the piston rings.

There's also some very similar-looking radial scoring going *around* the bore in both cylinder 1 and 4. It looks like a score mark similar to the longitudinal ones, but I have no idea how this would happen. Is there anything in particular this could indicate that I should be concerned about?

Finally, in cylinder 4 there are two different spots in the cylinder wall (roughly opposite each other across the cylinder, near the bottom of the stroke) with a dense cluster of what looks like pitting. My best guess about this is that it's a casting flaw that's been there since the cylinder was machined.

It looks like the cylinders are in pretty rough shape to me, but the engine runs. It's a little rough, and the piston seals clearly aren't great because there's gas in the oil and the exhaust is a bit smoky - now I know why.
I still plan to check the ignition timing, do valve clearances, and tune and sync the carbs - I'm hopeful that if any of these items are currently out of spec, fixing them might be enough to get the engine running reasonably smoothly, even if it is burning a bit of oil.

I would really appreciate any input on the condition of this engine.
Would y'all be looking at doing a top-end rebuild to get the cylinders in better shape? Is there anything else I should be looking out for that's indicated here that I'm not aware of?

Thanks for any input!

[eldevigo]

I'm including a google drive link to some additional photos from inside cylinders 1 and 4 that show some more detail, including the scoring and pitting mentioned above.

[zed1015]

Bores don't get polished after being bored.
They get honed which leaves a cross hatch pattern and yours look like fresh honing either after a rebore or just glaze busting for fresh rings on re-used pistons in the original bores.
Glaze busting may not remove all the previous running or corrosion marks so some vertical scratches and light pitting are likely to be still visible.
The horizontal mark around the cylinder is from where the engine has been sat and corrosion from a piston ring has left a shallow groove which the honing couldn't remove due to it's depth.
There's a limit on how far you can hone a cylinder for new rings in an old bore before you exceed the piston to bore clearance which would then require a rebore.
The piston seal will improve once run in if done correctly and oil in the bore may be not be due to ring seal but maybe valve stem seal leakage etc depending on what other work was or wasn't done..
Sounds like the engine had been stood a while then treated to a backyard refresh to clean up the rusty bores. .
It's anyones guess whether new rings were fitted or they wasted their time and re-used the old ones in which case the oily bores and smokey exhaust are here to stay until it's fixed correctly.

[Rich82GS750TZ]

I also think your pic just looks like a fresh hone. Gas in your oil is a problem but I can’t imagine condition of the cylinders or rings being a cause. I could be wrong. I’d look to the petcock (maybe left on prime) or otherwise faulty and/or the float valves in the carbs not seating or stuck open.

[Rob S.]

...honed which leaves a cross hatch pattern...

Sure looks like cross hatch to me.

[Big Block]

The proof is in the performance. Ride the heck out of it to make sure the rings are seated (if they can be). Then do a compression test. Sounds like backyard rering and it's either good or it's not. I find these GS' are pretty forgiving but they aren't miracle machines either.

[eldevigo]

Thanks for all the info! I did not know that this kind of crosshatching is normal, I'm pretty new to engine internals, so it's great to know more!

I also did not know that sitting unused for long periods could etch a cylinder wall like this, that's good info as well.

I don't know much about the history of the bike, but I believe the PO works for or is otherwise connected to a specialty vintage bike repair shop in town here, the shop name was in the title paper trail I got from him when I bought it.
He had a garage packed full of old japanese bikes, and from the number of maintenance items that look like they were recently done, my guess is that he bought this from someone else not more than a few years ago (maybe after a long period of neglect) and did some restoration work on it but then decided that he needed room in his garage and sold it again.

I hope it's a good sign that he bothered to put in the maintenance work, and not an indication that he found something too difficult or costly to repair...

[KiwiAlfa156]

As above. The hone pattern does a couple of things. It creates micro valleys and peaks (asperities) on the bore surface. During the initial break in the rings cut the peaks off and the peaks reshape the rings to match the exact shape of the bore. The bulk of this happens at the first start up after the hone and then continues gradually during the rest of the break in. So essentially it's wearing the parts together and essentially it's polishing on a microscopic scale.



Once this wearing process stops, the remaining micro valleys hold engine oil that prevents metal to metal scuffing been the piston, rings and bore.

Even on the highest mileage GS engines I've pulled down the hone has been visible. And that's a good thing.

[rphillips]

What would you have done if there were no bore scopes? I'd do just as Big Block says and hope the only evidence of anything off in the cyl.'s will be the pictures. If not you're right where you started.