Damaged cylinder wall?

[Chrisf]

20160910_092526.jpg

Hi everyone. New to the forum. Been working with my 17 yr old son on his project bike ('80 gs1000g) and saw this as we started cleaning up the cylinders. It looks like a horizontal scratch I've not seen anything like this before.

Had anyone else,and what are your thoughts? I've honed the cylinders,but I think it will take a lit more to smooth it out.

If it is shot, does anyone have a set of cylinders in good shape for a good price?

Thanks

[Chrisf]

Here's another view20160910_092516.jpg

[TeamDar]

That would be corrosion from the piston rings rusting against the cylinder. Looks too deep to hone out.

[1980GS1000E]

I have some similar damage to my CB1100F. It runs fine and has decent compression. Try honing it out with a bead hone and check the bore for clearance. If there is a mark still visible from the corrosion, but you can't feel it, you can run it.

[JTGS850GL]

I'm betting on that being a bore job. The pitting looks too deep to be able to be honed out without the risk of a ring catching.

[Sandy]

Looks like water was sitting in the cylinder. Hone it and see what it looks like and take it from there.

[Nessism]

That cylinder needs to be bored. Time to look for a new one.

[JTGS850GL]

I may have one that I can part with. Need to inspect it but I believe it's standard bore and in decent shape. Not sure what shipping the UT would be though. PM me if your interested.

[Steve]

Had a cylinder like that in my wife's 850 several years ago. We had run it for several years and about 15,000 miles or so before I pulled the head to have a shop extract some broken exhaust bolts. Replaced just the one liner, can't really tell any diffference in the way the bike runs with the 'new' liner. The one with the rusted-out area never caused any oil burning.

.

[geol]

If anyone has purchased a bike from a place like Florida that sat for even a few months outside with the carbs removed, they have seen that type damage. Liners are iron and rust at the drop of a hat when water is allowed to sit atop the piston for even fairly short times and the amount of damage depends on the length of time it sat. I would first try to hone and see if the cylinder bore continues to maintain the bore to piston service spec. if you can get a stock block and it is within spec and not ovaled, that would be even easier fix.

[Chrisf]

Thanks everyone. That's good to know about the water. The rings look ok, so I was a little baffled. I'll push a ring down in the cylinder and measure the gap. Once I've done that I'll decide which route to take. JTGS, I'll let you know. My son is itching to get this back on the road, but I want him to do it right so that he can enjoy it for years to come.

[Big Jay]

Time for a 1085 kit.