Cylinder Identification

[Missionguzzi]

Again seeking the knowledge and experience of all:   I recently came into a very nice Eldorado motor.   Before I tear it down, I'm trying to determine if it even needs it.  It was part of an unfinished project in an estate sale.  It is as clean as any I've ever seen, and may be completely rebuilt.  I checked the cylinder lining with a magnet through the spark plug hole, and it is mildly magnetic, that is, my small magnet sticks to the lining and requires a slight pull to get it to separate.  I used a mirror to look at the outside bottom fins to see if these were original or replacement cylinders.   As reference, I have a stock 850T motor with no marking on the bottom of the jugs.  I also have a stock iron-bore V1000 engine, likewise with no marking.  Another rebuilt 850T has Gilardoni Nicasil jugs, and is marked with the name "Gilardoni"



.  The recently acquired Eldorado jugs are marked with "Moto Guzzi" in the same location.  I'm aware that Gilardonis are marked, but do not know if Guzzi ever marked their cylinders in this location, or if Gilardoni added the Moto Guzzi marking to cylinders they supplied directly to the factory (not aftermarket).   Attached pictures will show the 850T and Eldorado markings.  Your enlightenment will be appreciated.

[Antietam Classic Cycle]

Again seeking the knowledge and experience of all:   I recently came into a very nice Eldorado motor.   Before I tear it down, I'm trying to determine if it even needs it.  It was part of an unfinished project in an estate sale.  It is as clean as any I've ever seen, and may be completely rebuilt.  I checked the cylinder lining with a magnet through the spark plug hole, and it is mildly magnetic, that is, my small magnet sticks to the lining and requires a slight pull to get it to separate.  I used a mirror to look at the outside bottom fins to see if these were original or replacement cylinders.   As reference, I have a stock 850T motor with no marking on the bottom of the jugs.  I also have a stock iron-bore V1000 engine, likewise with no marking.  Another rebuilt 850T has Gilardoni Nicasil jugs, and is marked with the name "Gilardoni"



.  The recently acquired Eldorado jugs are marked with "Moto Guzzi" in the same location.  I'm aware that Gilardonis are marked, but do not know if Guzzi ever marked their cylinders in this location, or if Gilardoni added the Moto Guzzi marking to cylinders they supplied directly to the factory (not aftermarket).   Attached pictures will show the 850T and Eldorado markings.  Your enlightenment will be appreciated.

In my experience, the cylinders with the cast in "Moto Guzzi" were originally chrome plated. Could be someone has already had them replated with nickel-silicon-carbide. If the magnet has any attraction at all, then it isn't chrome.

[Missionguzzi]

Thanks, Charlie.  So now you've raised a new question:  Many (most?) early cylinders manufactured in-house by Moto Guzzi do NOT have cast-in markings.   I don't recall seeing any before among the couple dozen early Guzzis I've worked on - but I haven't specifically looked for them.  My current 850T with original jugs and my V1000 iron-bore have no markings.  So it appears that Moto Guzzi had some concurrent models being built with both marked and unmarked cylinders.   That's entirely possible, because casting molds have to be updated and replaced over time, even if the dimensional specs remain the same.  I'm curious as to whether there's any clear-cut dates or models on which the cylinders were or were not marked.  This Eldo engine is a VP062xxx, which I believe is late 1974 to 1975, which would have been some of the final loop frames built.  My 850T with original jugs was built in this same time frame, without markings.  I also wonder if Guzzi used outside suppliers at any point for cylinders (maybe none, maybe some, maybe all?).   I'm not deliberately trying to rekindle discussion of arcane Guzzi history, just to understand if the "MOTO GUZZI" marking is an anomaly or was a long-standing practice for a portion of their cylinders.   I suppose a benchmark would be if any OTHER cylinders, such as Ambassador, 850T, T-3, etc, had marks such as these.

[Frenchfrog]

About two years ago I read from a very good source that the nicasil barrels supplied via Moto guzzi had the same small rectangle at the bottom of the fins but instead of Gillardoni being cast in there was no lettering what so ever.But I'm 99 % certain that this would only apply to supplies after 81 /82 and logically fully assembled machines.

[Antietam Classic Cycle]

Thanks, Charlie.  So now you've raised a new question:  Many (most?) early cylinders manufactured in-house by Moto Guzzi do NOT have cast-in markings.   I don't recall seeing any before among the couple dozen early Guzzis I've worked on - but I haven't specifically looked for them.  My current 850T with original jugs and my V1000 iron-bore have no markings.  So it appears that Moto Guzzi had some concurrent models being built with both marked and unmarked cylinders.   That's entirely possible, because casting molds have to be updated and replaced over time, even if the dimensional specs remain the same.  I'm curious as to whether there's any clear-cut dates or models on which the cylinders were or were not marked.  This Eldo engine is a VP062xxx, which I believe is late 1974 to 1975, which would have been some of the final loop frames built.  My 850T with original jugs was built in this same time frame, without markings.  I also wonder if Guzzi used outside suppliers at any point for cylinders (maybe none, maybe some, maybe all?).   I'm not deliberately trying to rekindle discussion of arcane Guzzi history, just to understand if the "MOTO GUZZI" marking is an anomaly or was a long-standing practice for a portion of their cylinders.   I suppose a benchmark would be if any OTHER cylinders, such as Ambassador, 850T, T-3, etc, had marks such as these.

Some Guzzi cylinder heads has "ROSI" cast into them, but they seem fairly uncommon, same with the "Moto Guzzi" cylinders . Rosi is reportedly a foundry, so it's quite possible that Guzzi used one or more foundries to cast the cylinders as well. After DeTomaso took over, I don't think Guzzi was casting cylinders and heads in-house, maybe even before that.

[Missionguzzi]

Thanks for all the updates.  I had hoped the "Moto Guzzi" stamp on the cylinders would give a clear indication of when/what these are, but it seems like a mixed bag of possibilities.  I'll go ahead and remove the heads to examine the cylinders.  Maybe I'll be lucky (Nikasil), maybe not....   Thanks again.

[Antietam Classic Cycle]

Thanks for all the updates.  I had hoped the "Moto Guzzi" stamp on the cylinders would give a clear indication of when/what these are, but it seems like a mixed bag of possibilities.  I'll go ahead and remove the heads to examine the cylinders.  Maybe I'll be lucky (Nikasil), maybe not....   Thanks again.

Since you wrote: "I checked the cylinder lining with a magnet through the spark plug hole, and it is mildly magnetic, that is, my small magnet sticks to the lining and requires a slight pull to get it to separate.", they are Nikasil. If they were chrome the magnet wouldn't stick at all, and if they were iron liners it would stick more.

Still worth disassembling to check rings gaps, piston pin bushings, etc.