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Discussion Starter #42
All good, I already got one coming from Omaha Ducati for cheap.

I got my piston all cleaned up and I noticed this bit of damage. Should I still run it? Should I make an attempt to deburr the damage and run it?

225446

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Discussion Starter #44
The engine is all back together and I noticed an impression, identical to what was on the piston, on the head. I have no idea how I didn't notice this before. I might just torque the head down and see if I can somehow run a compression test on the bench. I'm doubting it'll affect compression much, but if this will likely cause other issues, should I look into finding a used head? If I can find a used head, can I transplant all the internals from my head to the used one?

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The engine is all back together and I noticed an impression, identical to what was on the piston, on the head. I have no idea how I didn't notice this before. I might just torque the head down and see if I can somehow run a compression test on the bench. I'm doubting it'll affect compression much, but if this will likely cause other issues, should I look into finding a used head? If I can find a used head, can I transplant all the internals from my head to the used one?

View attachment 225454
I think it's eaten a screw sometime.
Check your butterflies for a missing screw.
That might have been enough to bend a con rod, I hope that's not the knocking sound.
Is that a scratch on the gasket mateing surface?
 

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Yes, the thread pitch seems to match the mark on the piston. How truly bizarre. Would be interesting to see where it came from. And ended up for that matter. Have you pulled the valves to see what kind of shape the mating surfaces are in? Sure looks like that exhaust valve may have nibbled on it as well.
 

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Discussion Starter #47
The valves are new from what I was told. I've also tested the compression on that cylinder with some oil in the cylinder and got decent compression. The bike bent either one or both valves because the timing belt skipped and was taken to some shoddy shop where they fixed the valves and I'm guessing they saw this damage and left it. I checked the carbs, the butterflies aren't missing a screw but that was a good guess. I'll have to trace back through the intake and see if I can find a bolt or screw that matches. The scratch on the mating surface is more of a step weirdly enough, but I'm assuming it seals fine because of my compression test.
 

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Sounds like the belt may have slipped because the valve couldn't quite swallow the bolt. Anyway, sounds like you're going to make a survivor out of it. For that I definitely say hats off to you with much respect.
 

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Hmm, the plot thickens, but you have good compression. (y)

Don't bother back tracking intake, I have seen this indentation before in a head, no way a bolt with thread that size/diameter, could get through the valves to cause this, It could only be the tip of the spark plug breaking off, taking a part of the thread with it. Skipped the timing belt they said?, fixed the bent valves?? you can't fix valves, replace yes, but valve damage/small nicks is evident, Hmmm.?? The only time I've seen the end of a spark plug break off like this, is in a 700 HP V8 ski race boat, LS Chev with aluminium heads, extreme revs under load. (Yes, once was young and reckless.)
Either the plug threads were shot, which can lead to crack/stress on plug thread when installing, plug 'seriously' overheated, or simply broken plug caused by forcing it in. Forcing it in would cause more damage to aluminium head thread though.
You have the head on already, but I'm positive if you checked that thread indent with a spark plug, it would match.

Please do check the spark plug screws in freely.
you have good compression, so valves are seating properly. Head should be ok.

I'm with Davy here, your doing well, and being thorough.
Personally, the most concern for me, (well, one of them) is the missing 'O' ring in the clutch cover, this would cause a drop in oil pressure, even though it just routes to the oil pressure switch. But hopefully it was just the tosser who last worked on the engine who forgot to put it in.
When starting, check that red oil pressure light goes out.
Knocking at higher revs often does not relate to big ends or crank, (well????) usually low revs and acceleration, more likely a rattle from the loose alternator.

Again, I ask the question, where has all this metal gone? Once up and running, I would drop the oil and have a close look for particles, put it through a fine filter. I would use basic good oil at first just in case, no point in wasting synthetic expensive stuff. After an hour or so running, check. If no particles, then put in the good stuff. If lots of crap in oil, maybe needs a couple of changes in first 100 k's to clear, then change filter also.
something to be aware of.

Keep up the good work, and keep us informed how it works out,
 

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Discussion Starter #50
I got the belts on and ran a compression test on the bench and got 95 psi again for the rear cylinder again. This has to mean it's a problem with the head because the piston, rings, and cylinder are all different. I'm guessing it's that step on the gasket mating surface so I might as well just try and find a different head. Overall, I'm more than happy because I also got the same 135 psi on the front cylinder so I didn't mess anything up putting it all back together and I saw a couple of used heads on eBay for a decent price.

Yes they didn't fix the valves, they replaced them, but I did learn that the shop that replaced them initially was just tuning the carbs and the timing skipped while in their possession. It's a weird situation because they must've tried to cover it up after finding out why the timing skipped, but the bike would've been running horribly after getting it back from them. Surely whatever happened, it would've been their fault because if whatever caused it wasn't their fault, they wouldn't have anything to lie about. As for the spark plug idea, the impression does fit a spark plug, but there isn't any damage to the threads and both of the plugs seem to match in terms of age.
 

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Well, at some time it did break off a plug? left it's print in the head.
No head gasket, only 'o' rings.

Before changing head, check valve seating, and shims, best with head removed, each valve off the cam lobe, ie. fully shut.
pour a little petrol down the intake and then exhaust. If they are not seating then fuel will leak out past the valve. Type of leak gives a rough idea,
1. flows out easily, valves not seated, or shim closers too tight. equals crap compression. remove valve and check seating.
2. wetness evident around valve head, again, could be shims or valves just need a little lapping.
3. completely dry. usually good seal.

If you get the second, (2.) wetness, remove both shims and hold valve shut with hand and repeat test. tells you if in fact it's the seat or the shims.

lapping in valves is simple, with heads off. I usually do it every time I find shims are out, too tight closers can not fully shut valve, and the seats get a little burnt.

It's a simple test, may save you getting another head.
 

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Discussion Starter #52
When I did compression tests on the bike before I had the engine out, The compression shot up to 120 psi with some oil in the cylinder. Could that still be the valves?
 

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Before even messing with a leak down test I'd pull the valves. The exhaust at the very least. Looks a little suspect to me. I know it was supposedly replaced, but checking it anyway is a good idea. Once you get the shims off and the valve is loose, give it a few spins a see if it's remotely straight before taking it out of the head. From the photo, it's hard to say for sure, but it doesn't look like it's seating quite right. Mine had a piss poor valve job by the dealership at some point before I got it. But I think it will make it until next summer.

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As you discovered, there is no head gasket as such, I'm wondering if the head got distorted from the damage.
You can actually 'Lap' the head to the barrel, not an easy process as the range of rotation is very small.
usually a machine shop job.
But, the head to barrel seal can be checked using this method.
Do the valve seating check first. No point if valves are leaking.

With no o'rings in place, use some engineers marking, It' a blue coloured thing here, much like a marker pen.
mark continuous line around the step in head where barrel sits in, put head on barrel and rotate back and forth, you wont get much movement as other things get in the way. Visually check, the marking should be ground away evenly. You will see if there's any high or low spots. I have used fine valve lapping paste before as well. Be warned, lapping paste is abrasive, get it into cam bearings etc. not good and will need thorough cleaning.

In a Ducati engine with no head gasket, to answer your question, Yes, putting oil in cylinder can bring up compression if rings are worn, but also if this mating head seal is worn too. Unlike other engines with gasket, the oil will also fill any mating imperfection. It won't make any difference to the valves seating.
 

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Discussion Starter #55
The valves seem fine from the test and I don't have the tools to tear it completely apart so I just went ahead and ordered a different head. The head I ordered is from the same place I ordered the cylinder and piston from and belonged to the same bike. I'd feel better just getting rid of everything that shop touched anyways.
 

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Discussion Starter #57
Not yet, the head I order doesn't get here until Friday and I might not get to it right away since I've been busy with college lately.
 

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Discussion Starter #58 (Edited)
I got the head and it looks great, much better than the one I had, but I noticed that the timing belt roller on this head is a little different than mine. This new head is off of a 2001 m750 dark and mine is a 2000 m750. I had a look at the parts diagrams and the rollers have different part numbers and slightly different setups. Everything else seems the same though. Can they be swapped or do I even need to? I want to take the one off the new head anyway because I want to take the timing belt shroud off. The rest of my engine doesn't have any of the timing belt covers so it would look weird if I left it on.

2000 m750
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2001 m750
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If your talking about part number 3 'timing belt roller' they are the same and have same part number.
Later ones have an added flange behind roller, and special washer in front, with bolts to better support the toothed roller.
You can swap if you like, but the later system is maybe a bit stronger.
 

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Yeah, but the newer ones are adjustable and the older ones are not. If you had two of the newer style and wanted to mess around with cam timing that would be one thing, but I don't think I'd want one of each.
 
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