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Pieces of piston ring?

6383 Views 81 Replies 19 Participants Last post by  David C.
We removed the crankcase cover where the clutch is to see if we could figure out where the knocking was coming from, this is what we found in there; (not the penny of course, that is there for size reference.)

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Welcome to the forum...
Sorry for your loss. :(
Further teardown required and suggested...
I was hoping that the problem was a lifter or something easy, maybe top end so that we did not have to remove the entire motor, but at this point, I'm leaning more toward having to remove the motor to see exactly what I have gotten myself into.
Welcome to the forum. Question when you had it running was it running on both cyls?
Hopefully someone with more knowledge of the clutch system will chime in.

Yes, it was (is) running on both cylinders. The clutch appears to be fine, in fact everything else on the bike is in excellent condition for it's age.
Doesnt look like piston rings to me. If those pieces were whole, the diameter looks way too small to be rings. I was thinking snap ring also. Does a magnet stick to them?
Yes they are magnetic. I fished them out of the crankcase with a magnet.
Any chance they are pieces of worn out clutch plates? What year/model bike? Miles? Did you look at the clutch assembly?

I doubt bits that big would make it down into the crankcase without really tearing up the combustion chamber....that would cause noises far beyond some knocking and the pieces don't look all scraped up.
It's a 1985 VT500c with 24, 470 miles. (Could be 124,470 miles?)
Could be pieces of clutch plate, the clutch assembly appears to be fine.
I will post a picture.
That penny sure is dirty ;)

I think I`m leaning towards clutch component pieces...
Maybe a springlike keeper, The notched piece kinda looks familiar and similar to a keeper which resembles a keyring...
BUT there isn`t enough evidence, plus that large square looking piece appears to be from something other than the keeper I have in mind...

A parts fiche for your Bike would be helpful...
What engine???

It's a 1985 VT500C.
Here is a picture of the clutch, it appears to be fine.

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I'm starting to think that the pieces that I found and the knock are not related.

The knock sounds almost like piston slap, possible worn out piston arm?
Thinking outloud here...

Yes the clip/ring/fastener I described would hold moving parts in place on a shaft...
And OR act as a spacer between moving parts...
SO = This COULD be associated to the knock???
Everyone here (in my shop) seems to be thinking piston rod, but I can stick my finger in there and it does not have any play, but that doesn't mean anything.
Do any of those pieces fit together so we can have a better look??
I`d be digging out more of it, IF it were me...
My $.02 worth for free ;)
I went fishing around in the crankcase and the old oil again, and was only able to find one more piece. The inside diameter is close to 2 inches (Maybe 50mm?) and the thickness is anywhere from .008 to .012 inches (Around .25mm?)

Thanks for all of the help, I really appreciate it. Maybe I can return the favor some day. I own a machine shop (general, not automotive) if you ever need anything.

By the way, none of them seem to fit together fwiw.

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I think I would start by pulling the clutch apart.
Really? Did you see the picture in post #13? The clutch LOOKS ok, but I'm a machinist, not a mechanic...

The pieces in question could be left over from a previous parts failure that some lazy mechanic didn't fish out.
Interesting theory, I believe that you are probably correct. Someone probably replaced the clutch at some point, and left some of the swarf in there.
Having built a few motors, they do look like part of the compression ring. What Is a Compression Ring? (with picture)

OP, have you checked the compression?
No, I have not checked the compression yet.
I have the good fortune to be surrounded by mechanics here. My next door neighbor employs four of them, all have become friends of mine, but not one of them does motorcycles, just cars, diesels, forklifts, and heavy equipment. The head honcho thinks that it can't be compression ring because of the damage that the pieces would cause going from cylinder to crankcase. (His opinion, of course.)

One guy that works for me is a machinist and a mechanic, and he has some motorcycle experience. I have some experience myself, although I consider myself a machinist, I do have some experience as a mechanic, both cars and motorcycles.

We have all heard the stories of the difficulty of replacing the timing chains during re-assembly, but I think that with the shop manual, we could probably get it done.
I will check the compression next.
Being a 'mechanic' and not having 'motorcycle' experience means nothing. Just because youre not an expert on a v-twin doesnt mean you cant work on them. True, i they were pieces of the top rings its hard for them to get into the crankcase past the rest of the piston, but it doesnt mean they arent and werent left there after a rebuild or something.

I also could be wrong at my guess. But in most non start cases were fuel and spark are verified, compression should be the first thing to check. Just dont forget to leave one of the plugs in the cyl when you check it :D
Two of the guys that are helping me are Daniel and Randy. Daniel said that I don't need to test the compression if it's running. It will be at least 100 psi or it wouldn't run. Randy says, not a bad idea to check it anyway, it's free. So I borrowed Daniel's compression tester. Problem is that it's 14mm and the plugs are 12mm so it won't screw in there. So I call around, surely someone has an adaptor, Oreilley's doesn't have it, Advance doesn't have it, Auto zone has one, but I would have to buy the whole compression tester for $40. I only have $500 in the bike so far and I want to get it going without forking out a whole lot of cash. I could make an adaptor, after all, I have a full blown machine shop right here.

Bottom line is today is Saturday, and the Clymer shop manual is supposed to arrive on Tuesday. I have to try to be patient. The weather down here in Georgia is good enough to ride right now, and I have an itchy throttle hand!

Also, I found out yesterday that Randy has motorcycle experience. He said that a friend of his had an 1100 Gold Wing and the guy tried to rebuild it. He put the timing chain on wrong and bent some of the valves. He became frustrated and GAVE the bike to Randy. Randy bought new valves and re-worked the rebuild, had it running within 2 days.
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Of course, I didn't have the tap (m14 x 1.25) so I had to single point the thread, but no big deal. I now am the owner of a compression tester adaptor m12 to m14.

Checked the compression, 70 PSI in both cylinders. Is that good or bad?
Oh, and did you make an o-ring seal on the engine side?
Yes, I basically copied the existing sample only with the smaller thread, and I happened to have the right o-ring. Does 70PSI sound low to you?

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Maybe squirt a little oil in the cylinder and open the throttle and test again. Or open the throttle and test dry, and then try some oil. Just a little bit.
70 PSI (both cylinders) dry with throttle open, 120 psi front, 125 PSI rear cylinder with oil and throttle open. Either way, I have to tear this thing apart and see what the slap (knock?) is. I suspect a bad piston arm, but we shall see.

How about parts? Is there an OEM source for pistons and piston arms? What about cylinders? (I know that Honda no longer carries anything for this model. (It's 1985 VT500C)

I have a friend just up the road that does coatings on pistons, and I have a cylinder hone here.
With the plug removed can you put that cylinder at bottom dead center and with a bore scope or small flashlight, inspect the cylinder walls for scoring? Maybe take both plugs out and shine a flashlight...
I tried that. I can see the tops of the pistons, they appear to be normal. Without any fancy gadgets, I cannot see the cylinder walls.
Finally figured out where the problem is, rear piston is sloppy when you push/pull up or down. We will have to split the case but now that I have the shop manual, not so bad. Probably connecting rod bearings, hopefully I caught it in time before it ruined something else. Pistons and rings are fine, good shape actually. Valves need to be lapped a bit, not the end of the world by any means.

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Does anyone know where I can get a cam chain tensioner? I'm finding that some parts are available new here in the states, and some are available from Europe or Asia (gaskets coming from Japan).
This is for my 1985 VT500C
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