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Not really a reply- more of a comment-- read previous post-can't find it now but it had a reply from Dvy3178.
His last line to me was one of the best----to paraphrase 3178-- "anyone can buy a fast bike but the there is no more
enjoyment than make a slow bike fast " --- I thought it was something to remember. Thanks for the space..Bob329
 

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Discussion Starter #22
I'm located in Oregon. I'm pretty sure I'll go with the used option just for cost sake, but I can't be sure until I get the cases split and inspect the bearings, or maybe I can tell something is wrong once I'm in the clutch side or have the flywheel off. I'm still waiting on a 30mm socket for the flywheel nut. I did have a question about going with a used cylinder though. If I got just a cylinder would it have to surfaced to match my head since there is no head gasket on these bikes? Also, I did end up finding something in the alternator cover that has me a little puzzled. There are wear marks along the outside of the stator. If the flywheel caused them, I don't see any indication of it on the flywheel. Too much end float on the crank? I only just learned about that so not sure if I'm thinking about it correctly.
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Yeah that's kinda what it's looking like. The mark seem consistent in size and shape all the way around? I know you posted photos of the pistons with the heads off, I assume you have the cylinders off now if you're working on splitting the cases. How much play have you got on the rods?
 

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Discussion Starter #24
I got 0.30mm of play between the rods which is within spec. They don't have any vertical play either.
 

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Discussion Starter #25
I got the socket I needed and when I went to get the flywheel nut off, it was on hand tight. Not sure why that might be the case. I only have the alternator side torn down, but I'm not feeling any play in the crankshaft and it seems to turn smoothly. Would that mean the bearings are alright or do I need to split the case to know for sure? Ducati said the bike knocked at high rpm, I can't attest to that being that case since I never heard the bike run, but if that were the case what should I be looking for? They said it possibly had a bad crank, but I don't really even know what that means.
 

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Yeah, it's tough to say. Sounds like a lot of people have got their hands on it over the years. It could have just been shimmed wrong at some point. Thus the rubbing on the case cover. But if it's that far out, who knows what else it's affected. It's always something.. I've been keeping an eye out for 750 parts.

Of course if the nut was that loose, that could be your rubbing problem right there too.
 

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Discussion Starter #27
You are probably right there about the wear on the case cover. I wonder if that was the knocking Ducati heard at high rpm?
 

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You are probably right there about the wear on the case cover. I wonder if that was the knocking Ducati heard at high rpm?
Could have been. But I don't know what the piston situation was like at the time of that diagnosis. It's your call, but if you're just looking to get it going again and you're fairly comfortable with the bottom the way it is, might just want to hold off on the complete teardown. Slap another cylinder and piston on and go with it. See how it does. Saw a vertical set last night on eBay. $75 obo free shipping.
 

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Personally, I would split the cases. The main issue being, as I see it, Where has all that metal gone?
You have the main cylinder scoring, piston damage, now chunks of metal from loose alternator. Lots of broken stuff circulating. My concern would be the soft shells of the big ends, any hard metal, ie. the Nikasil coating, even aluminium from casings, could possibly embed into these relatively soft shells and turn them into, well abrasive, 'sandpaper' like, and can continue scoring the crank etc. The filter would eventually catch most, but not before further damage. Your halfway there, Peace of mind to be sure everything else is OK.

I guess it's up to you.
 

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All valid concerns. To me, frankly it's just too much work involved in order to just have look at it. I wouldn't mess with it without being prepared to go all in. New bearings, seals, having the crank gone through and checked, re-shim all the shafts and transmission in the correct order. It adds up quick. And after all that, put a used and abused top end back on? No, I wouldn't. so there's a few more hours for the machine shop. And more tracking down hard to find parts.

It is what it is. As it is now, once the parts are acquired, a few hours later it could be ridable. Not always, but sometimes waiting until something breaks before you fix it is the most sensible thing to do in my opinion.
 

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Discussion Starter #31
Ya, I'll probably just throw it together once I get some parts and try to get it running. If I find it's knocking, I'll tear it down all the way and fix that, and if it's not knocking then I've saved myself some cash.
 

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Discussion Starter #32
The used cylinder and piston I bought came today and they look fine, but I did notice that the cylinder is stamped with a "C" where my cylinder and piston are stamped "A". I don't know if the piston is stamped "C" also because of the carbon buildup that I'm still trying to clean off, but I'd imagine it is. Are these stamps just to match cylinder and piston or do they match with the head or something else too?
 

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I believe Davy's sizes are correct, very, very small difference. hundredth of a millimeter??
The piston should have a C also. (hopefully)
The ABC letters on pistons was done at the factory when assembling. All have standard size bore. The boring and plating process has very fine tolerances, but some slight variation occurs, therefore, to get it almost exact, they used 3 different size pistons. These are not intentionally 'overbored', yes, you are correct, letter just to match each cylinder and piston, the heads were all the same,( as for fitting) as were piston rings, when you could get them.
You won't have any issues with the head.


Hope this helps.
 

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Discussion Starter #35
That helps a lot, thanks.

I got the new used piston cleaned up enough to read the "C" stamp on it so that's good, but I also removed the piston rings and noticed some differences between my junk pistons' rings. The main difference is with the oil rings which are shown at the bottom of the picture. The rings on the left are from my junk piston (I broke the top ring because it was slightly seized) and the rings on the right are from the new used piston. The oil ring on the right doesn't seem to be broken so I'm not sure what's up with that, but my first thought is to just run the left oil ring with the two other rings from the new used piston.

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Not having a lot of luck hey.
The oil ring on the right is most definitely broken. Gaps a bit big I reckon.
Put the original into the bore, push down a little using the piston to square it up, measure the gap
Check your manual for correct gap tolerance. I'm guessing here from memory, 0.2mm-0.4mm for top ones. similar for oil but, Maximum of 0.8 .

But mainly, If you decide to use it, check that oil ring carefully, for scoring etc. run your finger nail around edges, feel and look for scratches etc. I sometimes use a big magnifying glass to check things. I'm not going to recommend using it but it may be ok.
New rings are hard to find.
 

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Discussion Starter #37
This used piston I got had a lot of carbon build-up and I got most of it off, but I think I may have been a little too aggressive with removing it because the top of the piston is a lot duller than my other piston and you can't see the circle pattern on it anymore. I mainly used gasoline and a brass wire brush. Am I still good to run this? I was gentle with the skirt and elsewhere so that all looks great. The piston rings are all well within spec as well.
 

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The top of the piston can be polished up a bit with medium then fine emery paper no problems, I've seen guys polish the tops to a mirror shine. In the belief that it prevents excessive carbon buildup and removes stress marks and sharp edges..
The wire brush does dig in a bit, and scores the aluminum, but you should be good.
Just check the ring grooves, make sure no carbon buildup. An old method for cleaning the grooves was to use old broken rings and push around the groove to remove carbon. Make sure the rings rotate smoothly in the grooves before installing etc.etc.
Give it a good wash after any sanding.

Nearly there..
:D
 

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Discussion Starter #39
Does anyone have a part number for the oil way o-ring behind the clutch cover? I can't find it in any of the parts diagrams. My bike didn't have one at all.
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