Iron Cylinder Liner Wisdom Sought

[shiskowd]

Mr. Richardson makes it pretty clear in Guzziology that he's not a fan of installing iron liners in the old chrome bore cylinders.  He does offers some suggestions if you do go the liner route including installing the liner such that it extends slightly beyond the cylinder by machining the seat in the cylinder wall that is shallower than the flange at the top of the liner.  His theory is the head and gasket will keep the liner and place and will prevent it from settling further into the cylinder which often happens.  "If the liner falls below flush, cylinder compression will leak under the head gasket into the pushrod holes, causing the engine to overheat, knock and flow a combination of hot air and oil out the engine breather."

I'm in the early stages of restoring a '75 850T (https://wildguzzi.com/forum/index.php?topic=102453.0) that had iron cylinder sleeves installed many years ago but has run little since (speculation).  While the cylinder bores look near perfect, it appears the liners were installed much differently than Dave suggests.  The iron liners (about 2.25mm thick) were installed from the cylinder bottom and pressed into a bore that wasn't cut through the top of the cylinder, about 1.5mm short, creating the very scenario that I quoted.  There is no flange that will prevent the line from sliding down the enlarged cylinder bore.

Am I worrying about nothing??  I'd hate to spend the $ on Gilardoni cylinder/piston kit but if it makes sense in the long run...  I haven't measured out the rings or piston clearances yet.

[pete roper]

I once installed parallel liners in a V7 at the behest of a man I respected. I was sceptical but had no reason to doubt his knowledge or certainty that it would work.

It didn't. The liners dropped until the top ring popped over the top and on the next downstroke the liner was dragged into the crank. The other side was dropping too. It was a clusterf%*# of epic proportions.

If you want to stick with iron liners I'd suggest a set of 'Top Hat' sleeves from LA sleeve but in all honesty a much better option is just to spring for a set of Gilardonis and be done with it forever.

Pete

[shiskowd]

And then there's this that I noticed tonight...  confident the middle ring has excessive ring end gap. The rings are 2mm, 2mm & 5mm (oil ring) thick.  Where would I find such a set of rings??

[JC85]

What Pete said. A set of Nykosil cylinder kits will cost, but not that much, relatively speaking. About $800 total. The install can be done in an easy weekend with mostly basic tools, and then you'll have brand new jugs, pistons, and rings, and never have to worry about the cylinders again.

[Antietam Classic Cycle]

And then there's this that I noticed tonight...  confident the middle ring has excessive ring end gap. The rings are 2mm, 2mm & 5mm (oil ring) thick.  Where would I find such a set of rings??

http://www.deves.com/devesrings/cycles_MOTO_GUZZI.php

[wirespokes]

A cheaper route is to source a set of old chrome bore cylinders and have them nikasil plated. I forget what that would cost, but seem to recall in the range of three to four hundred.

[canuck750]

I would be reluctant to spend anything on reviving the iron lines cylinders and trying to find new rings. Had the liners been done by LA Sleeve as Mr. Roper suggested then it would be a different situation (LA Sleeve just relined my Moto Morini 500). New Giladorni are the best solution. I had one set of chrome bored replayed by Milenium’s shop in Winnipeg but only because I wanted to keep the bike all stock.

Cheers Jim

[s1120]

I gotta say Ive never seen a set of liners way. Granted im used to working on bigger stuff like cars, tractors etc...  But ive always seen them them go in from the top with a small step to flange then in place.

[pete roper]

What I would refer to as a 'Top Hat' liner, although if you are astonishingly dim, you should realise that the hat is inverted and the brim acts as the locator.

And no. Paul I'm not suggesting you are 'That Guy'

Pete

[cliffrod]

I've debated the cylinder replate/line/update for my V700 project. 

I replaced the original cylinders on my V7 Sport long ago with new nikasil replacements from Guzzi, back when they were available.  Multiple experts said I could go with liners but it had real risks. So I bought new ones and ate bread soup...   People familiar with the chrome issues will now specifically ask if I've replaced the chrome bore cylinders because there is no external cues to identify them on these old replacement parts.  It's clear from reactions that many still have doubts.  Someday everything is sold and I expect potential buyers will use that claim by me as a negotiating detail.  That's why I have the original peeling cylinders & pistons in the Guzzi boxes on the shelf.   

They weren't cheap, but it was a simple & quick to install the new parts and are complete peace of mind versus two-way shipping for my old cylinders + new parts + labor plus rings (and maybe pistons) + shipping from a separate source.  If you use a local shop instead of a national-reputation shop, no matter how good they are, you'll always have to convince skeptical potential buyers that they really are qualified...  Receipts are just paper.

For the V700, I'll do the same with new Gilardonis instead of trying to save a relatively small amount of money.  Even though they'll likely be "incorrect" 750 jugs turned down to fit the V700 block, the external id will instantly help any buyer be confident that I'm not just saying I addressed a necessary serious concern with the bike.  I'll consider the extra cost as money well-spent to help sell the bike later and will eat some more bread soup.

[MattP]

why are you posting photo of cylinder top with head gasket on it?

[TOMB]

Looking at the  picture of the Piston there's no way to say that the ring gaps are too big you have to take them off the Piston put them in the cylinder and then measure them apparently in the picture it's just the spring opening before they are compressed to be put into the cylinder sleeve do a ring end Gap measurement and then go from there
TOMB

[shiskowd]

why are you posting photo of cylinder top with head gasket on it?

Ugh - good question!  I'll remove tonight and re-post with out the gasket.

[Don G]

Drop those cylinders and pistons in the scrap bin, bite the bullet and purchase new Gilardonis, I have seen a number of sleeves come loose and rotate due to the interference fit between the cylinder and sleeve. The Gilardonis will last forever almost, they will seal way better than the cast bore and also run cooler that the cast lined bore. Just cuz it works, dont mean its right.

[hauto]

Before you drop big money call Power Seal in Pennsylvania and talk to them about your situation.

[shiskowd]

OK, I've been pretty clear I'm a newb at this MG restoration stuff, but generally above average(?) mechanical aptitude.  Even so, as MattP pointed out, the pictures I took and my conclusions were based on my observation with the HEAD GASKETS STILL ON THE CYLINDER 

With that out of the way, below is a picture the top of a cylinder without the head gasket.  The liner is flush with the top of the cylinder but doesn't have the preferred 'hat' or flange to hold the liner from slipping down the bore. Liner is the same ~2.4mm thickness it is on the bottom.  The pistons in this bike look new'ish probably because they are, likely replaced when the iron liners were installed.  Everything I've read suggests the '75 850T would have had 4 rings, the ring arrangement on these pistons (2mm, 2mm & 5mm (oil ring)) wouldn't be stock on any 83mm bore that I could find.

Appreciate all the feedback, decided I'll 'eat bread soup' and invest in new Gilardoni cylinder/piston sets.  I want to pass this bike on to my sons at some point and don't want to pass along the reliability uncertainty.

Looking at the  picture of the Piston there's no way to say that the ring gaps are too big you have to take them off the Piston put them in the cylinder and then measure them apparently in the picture it's just the spring opening before they are compressed to be put into the cylinder sleeve do a ring end Gap measurement and then go from there
TOMB

I installed the rings in the cylinder using the piston to square them in the bore.  Ring gap for the two comp rings > 0.8mm top (which I believe is 2x out of spec) and 11mm bottom which is also slightly out of spec(!). Likely a ring set would be in order if I kept the iron lined cylinders (trying to justify...).

Before you drop big money call Power Seal in Pennsylvania and talk to them about your situation.

I don't know Power Seal has a solution as the bored out cylinders (to fit the liner would) wouldn't be suitable for re-plating.

[Antietam Classic Cycle]

The pistons in this bike look new'ish probably because they are, likely replaced when the iron liners were installed.  Everything I've read suggests the '75 850T would have had 4 rings, the ring arrangement on these pistons (2mm, 2mm & 5mm (oil ring)) wouldn't be stock on any 83mm bore that I could find.

I guess you missed the link I posted:

http://www.deves.com/devesrings/cycles_MOTO_GUZZI.php

Second from the bottom: MC-125 for an Eldorado. 

[shiskowd]

I guess you missed the link I posted:
Second from the bottom: MC-125 for an Eldorado.

I did see that.  The kit has the ring sizes I could use but my comment was more that the pistons I have are unique (2.0/2.0/5.0) even from that Eldorado.

[MattP]

If it were mine
i would pin the sleeve with a couple 8/32 flat heads counter sunk lock titeted below the ring travel. You can get any ring you want from total seal, very cheap, Note they are vary helpful on the phone. Matt