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Discussion Starter #222 (Edited)
Those rocker arms would make it sound like a bag of hammers. But now you are in there keep looking.
Holy shit the bearings on this thing are spendy! I am going to get some plastigage and check clearances, just to see whats going on. Hopefully they are within spec and I can put it back together.

I seem to have sorted out the camshaft issue, which makes sense. I was suspicous when I mic'd them initially, having lost 2mm of diameter would basically make them round and they still look very egg shaped. According to several of the German forums I follow, the camshaft I have was made for city use, and lots of guys have done the swap only to notice no difference unless they are on the track or on the BAHN. I won't be taking this thing anywhere outside of town, at least not often. For now, I won't worry too much about converting it over, especially since I can pick up a very nice, used VFR750 for under 800 bucks any day of the week here.

So with the knocking sound.... Here is where I'm at.
- No play or excessive wear with conrod bearings (before plastigage)
- No play or excessive wear with Main bearings (before plastigage)
- Balancer chain was less than halfway stretched (according to teh detent in the adjustment shaft)
- Balancers are newer version which do not use cush drives for the sprocket.
- No excessive wear or chipping on either the balancers or their respective bajillion different chain/tensioning matrix structure components.
- Lower end looks good for now, just gotta check clearances on journals to be sure.
- Top end was worn as fuck, and now I have the replacement rocker arms. Camshaft isn't out of spec, so it will likely be re-used.


What am I missing here?
 

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What am I missing here?
Buying that VFR750 for under 800 bucks.


You know how to measure a chain for stretch? <- lay it along side a new chain.
+ I am trying to imagine what would cause so much wear on your rocker arms unless they were starved for lubrication and that should result in lots of damage throughout :confused:


"the camshaft I have was made for city use, and lots of guys have done the swap only to notice no difference unless they are on the track or on the BAHN."
In their dreams maybe. The whole bike was made for casual use, it was built to compete at the price tag, not at the track.
 

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- Top end was worn as fuck, and now I have the replacement rocker arms. Camshaft isn't out of spec, so it will likely be re-used.

What am I missing here?[/QUOTE

“Usually” when rocker/followers are that knackered, there is a least some corresponding wear on the cam. Are you sure that cam is reusable? Might be an idea to post a photo here or on one of the others forums. Installing new rockers on a cam with any scoring isn’t money well spent. When ordering those shell bearings, quantity 1 normally gets you one half shell. Read up on bearing selection if you do end up needing them. They are a select fit.
 

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Discussion Starter #225
So, heres bearings. I did the trigonometry to figure out which ones are in my shitbox. Hopefully I'm correct? Looks like itll be about 100 euros for all 10 halves, from threedifferent sellers. I have the math done for the Conrod bearings as well.

Might have to pull the trigger on the VFR.
 

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That' your crankshaft, what do the soft bearing surfaces look like where the hardened crankshaft has been banging into them, (after you wipe the oil off)
if they are perfect your crank is probably dandy and the bearing tolerance codes still apply,
if the old bearings are hammered then the crank is in question.

Considering the supply chain, so much to replace, so much to go wrong.
... and if you are in that far and don't replace the crappy primary chain it is a bit of a waste. (make sure your next bike has a gear primary drive)
 

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IF a picture can tell their condition I'd say they are done but not horribly damaged looking.
Here is the thing, there is nothing except an ultra thin layer of oil those bearings are suppose to be running on and that layer of oil is dependent on oil pressure feed. As the oil bearing clearances increase due to wear, your oil pressure drops throughout the system, engine clatters, some parts (like cam followers) can wear very quickly if they become starved for oil. In the battle of metal the steel parts will always survive the softer metal bits. imho you just need to replace a lot of soft metal bits. (it just sucks for you that those parts are now old rare and expensive)
 

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Discussion Starter #229
IF a picture can tell their condition I'd say they are done but not horribly damaged looking.
Here is the thing, there is nothing except an ultra thin layer of oil those bearings are suppose to be running on and that layer of oil is dependent on oil pressure feed. As the oil bearing clearances increase due to wear, your oil pressure drops throughout the system, engine clatters, some parts (like cam followers) can wear very quickly if they become starved for oil. In the battle of metal the steel parts will always survive the softer metal bits. imho you just need to replace a lot of soft metal bits. (it just sucks for you that those parts are now old rare and expensive)
That's good looking out. I ordered the plastigage and have located the bearings online. I will get them coming in here.

I want to plastigage the journals with these old bearings to see if they could possibly have been the cause of my clanking sound. It would probably be foolish to not replace the bearings after going to the trouble to split the cases. But I still need to find a better explanation for the clanking sound than just worn out rocker arms.
 

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If you find anything that would induce low oil pressure you likely found the culprit.

How are the cylinder walls, rings and pistons looking? On an air cooled motor you can really hear the pistons rattle if everything is not perfect in there.
 

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I suspect that you already found the problem with those rocker arms. Get a new or replacement set or have them refaced by Megacycle or a local supplier. Those shell bearings are what you would expect to see after all these years and are probably still in spec. Check that with plastigauge as you mentioned to be sure.

Typically a rocker to cam noise is a light sort of tapping and big ends tend to be a deeper noise. sort of like a big hammer against an anvil compared to a small one in terms of sound.

You should measure the piston to bore clearance while it's in bits to see if worn bores are contributing to the racket.

Those motors sort rustle rather rattle as a rule.

Check parts list at CMSNL to see if they use the same pistons and parts as general export models and get a camshaft with bigger bricks on it if it will fit.
 

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Discussion Starter #232 (Edited)
Pistons are somewhat worn, to the point that they are out of spec I think. I mic'd them both at about 70.3mm, and service limit is 70.40mm. Piston/bore clearance is .13mm - .15mm, which is outside service limit. I don't have a dial gauge to measure cylinder OD. but it seems like the old pistons are a little worn. They show standard marks of wear, the bore is not scored. I inspected it and honed it already, it looks clean.

Is there another way to measure bore OD without a dial gauge?
 

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Is there another way to measure bore OD without a dial gauge?
ID

Yes, run your finger (or inside callipers) up and down on the cylinder bore from where the piston rings do contact the cylinder bore, to where they never contact the cylinder bore and see if there is a difference, you don't even need to know how to read a micrometer that way.

If there is visible wear on the pistons you found another problem, in a perfect world pistons never ride in contact with the cylinder bore, the rings do.
 

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Discussion Starter #236
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Is there another way to measure bore OD without a dial gauge?
ID

Yes, run your finger (or inside callipers) up and down on the cylinder bore from where the piston rings do contact the cylinder bore, to where they never contact the cylinder bore and see if there is a difference, you don't even need to know how to read a micrometer that way.

If there is visible wear on the pistons you found another problem, in a perfect world pistons never ride in contact with the cylinder bore, the rings do.
Okay back up here. Piston/bore clearance I measured without the rings on the piston. After that, I have a new set of piston rings, which I placed in the honed bore (compression ring) and measured the ring end gap. The ring end gap was exactly spec. I measured the ring end gap at 3 different heights in both bores and the reading was the same for all sites. I shined a flashlight under the rings and there was no gap between the rings outside edge and bore.

This means the cylinders are serviceable, correct?
 

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Certainly sounds like you have a good tolerance fit between your rings, piston and the cylinder bore, that is a good thing,
but if I was going to measure the cylinder bore, I would be inclined to just measure the cylinder bore.

 

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Short skirt. #streetwalker. Gotta wonder about longevity on that one... Don’t think my long stroke air cooled thumper would survive with one of those given the clearances I need to run. Speaking of pushing the limit.

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