Heresy chrome bore question

[motogman]

heresy    noun her�e�sy \ a belief or opinion that does not agree with the official belief or opinion of a particular religion

I understand from researching the topic that the chrome bores will fail.  It is not a matter of if but when.  I also understand that sitting for long periods creates a worse condition (although I can not find out why this is) and seems to aggravate the failure of the chrome.

So here is where the heresy comes in...   

I want to put my chrome bores back in service.  My question is this...  what prep of either the bore, the rings or both should be done to put a chrome bore set of pistons and jugs back into service after having them disassembled?

Do you do a light hone or a light ball hone on the bores?  Do you leave the bores alone and deglaze the rings?  Do you use new rings?

What was the factory recommendation before people figured out that the chrome was a unreliable solution and needed replaced?


I know I will catch a lot of grief for even suggesting to put old chrome bores back in service but please humor me.

The other question is...  besides Gilardoni kits, what other options are there for redoing the bores and what are the problems with these?

[oldbike54]

 How is any kind of prep going to keep the chrome from flaking off ?

  Dusty

[lucian]

Nikasil

http://www.mt-llc.com/about.php

[Chuck in Indiana]

Do you do a light hone or a light ball hone on the bores?

As far as I know.. no honing on chrome *or* Nicasil bores. If you are determined to run chrome bores, I'd put new rings on the pistons, and run the crap out of them for the first hour or so.
That's not to say that is what I'd do.  You probably know as well as I do that you are playing Russian Roulette.  Good luck with that.
"Click" Whew. 

[Antietam Classic Cycle]

I want to put my chrome bores back in service.  My question is this...  what prep of either the bore, the rings or both should be done to put a chrome bore set of pistons and jugs back into service after having them disassembled?

Do you do a light hone or a light ball hone on the bores?  Do you leave the bores alone and deglaze the rings?  Do you use new rings?

What was the factory recommendation before people figured out that the chrome was a unreliable solution and needed replaced?


I know I will catch a lot of grief for even suggesting to put old chrome bores back in service but please humor me.

The other question is...  besides Gilardoni kits, what other options are there for redoing the bores and what are the problems with these?

Running chrome bores is like this:



except five chambers are loaded. Why you'd want to take the chance of damaging your engine is beyond me. To save money? False economy. It will end up costing you more in the end.

But, if you insist. No honing or deglazing, new rings. Cross your fingers, say a prayer.

Before Nikasil replating became widely available, iron liners was the fix. You can still go that route, but it'll cost just as much as having the cylinders replated in Nikasil and won't work as well, IMO.

As far as I know.. no honing on chrome *or* Nicasil bores. If you are determined to run chrome bores, I'd put new rings on the pistons, and run the crap out of them for the first hour or so.
That's not to say that is what I'd do.  You probably know as well as I do that you are playing Russian Roulette.  Good luck with that.
"Click" Whew. 

"Great minds think alike". I just type slower. 

[canuck750]

No honing or special prep. Chrome will eventually destroy the main bearings, rod shells, small end bushing and oil pump not to mention a crank regrind. If you have a filter engine then the bearings might still be ok and no crank regrind required. Once the bearings go you will add $1000 to the rebuild.  An engine that sits collects condensation which enhances the corrosion.

[redrider90]

Heresy is the notion of going against a belief system that is faith based. If you are inclined to reuse chrome bores then you are not committing
heresy. You are committing an act of faith that you will not totally destroy your engine as it flakes off chrome. I. It is not a belief system that chrome bores flake and destroy the innards of a Guzzi. It is a fact that the chrome will flake off and destroy the innards.
 

[guzziownr]

I recently parted out a low-mile chrome-bore T-3 that was (a)  In a flood, and (b) left to rot uncovered for decades.  The chrome came off the bores in perfect sheets.  from this single data point I conclude:  Wet is bad. 

Do you live in a desert?

Has the bike been stored in a low humidity environment for the last 35 years?

Are you a gambling man?

Is Las Vegas a fun place to live?  I have never been...

[Kiwi_Roy]

I know of two Eldorados running on chrome bores, one owned by a dealer the other by a machinist.

I have a theory that chrome being porous allows the moisture to migrate below the surface when started the moisture turns to steam blasting the chrome from the surface
I would warm the bores in an oven then give them a good coating of oil.

Nigasil is the safe way to go.

[jacksonracingcomau]

I've seen many high mileage chrome bores still intact, seen others worn out without flaking
seen others flake with very low mileage
Nor sure if it truly is when not if, but at your own risk, for sure. check under magnifying glass there is no damage now, at least.

Dry climate much kinder, as is daily use, parked they can flake without even running, parking them was not in design specs
KR 's warm in oven can't hurt anything, interesting if nothing else,

[John A]

One of the contributating factors of chrome failing is the expansion rate difference between the aluminum and chrome as it heats up and cools down. Why don't you sell the bike to someone who can take care of it?

[Kiwi_Roy]

Before the Giladoni kits became available again I seriously considered running with the original bores but adding an oil filter, I figured any small flakes
would make it through the pump once to get filtered out long before the bearings. There is enough room inside the sump to add a filter, its the piping
to and fro that's the challenge.

[Charles in Lake Charles]

Consider http://www.lasleeve.com/products

[Antietam Classic Cycle]

Consider http://www.lasleeve.com/products

I was quoted $98 ea. for sleeves, $110 ea. to bore the cylinder block, install the sleeve and bore it to match the piston. So, $208 per cylinder - $1 less than having them Nikasil plated.

[Perazzimx14]

If you going to run the chrome bores I say do nothing special prep wise. In fact no new gaskets or rings, just slap it all back together. There is no sense spending money on gaskets and rings because as soon as the chrome flakes and does about $2,500 in damage your going to need that cash to put towards a total rebuild.

[Kiwi_Roy]

I was quoted $98 ea. for sleeves, $110 ea. to bore the cylinder block, install the sleeve and bore it to match the piston. So, $208 per cylinder - $1 less than having them Nikasil plated.

Charlie, you must get special pricing, I enquired about getting my cylinders Nikasil plated, by the time I got them back it would have been almost the cost of the Giladoni kits and that still left me with old pistons

[Antietam Classic Cycle]

Charlie, you must get special pricing, I enquired about getting my cylinders Nikasil plated, by the time I got them back it would have been almost the cost of the Gilardoni kits and that still left me with old pistons

Last I had some done at Millennium (V7 Sport, March of this year) $209.90 was retail, my cost even lower.

[motogman]

So I have to say I got what I asked for     and expected with this thread.  So a couple of thoughts...

1)  Some threads reinforce a view that some chrome bores will bad and some are OK which suggests the problem is more a manufacturing process variability problem than a fundamental material design issue.  It would not surprise me that the Italian manufacturing process controls were not well understood and were not well controlled.

2)  One of the problems I was facing was that Gilardoni kits are less available for the V7 (82.5mm) bore than others so I was not sure I could find them.  You have given me some other options to consider...

Option a)  replate existing bores with Nikasil (via Millennium).  I got a quote today similar to what Antietam Classic stated and did some more research on this approach.  Sounds pretty appealing -  so what are the down sides?

Option b)  I was told that a Gilardoni kit for the Ambassador will work with a V7 -  seems V7s were 82.5 mm bores for something like 748cc and Ambos were 83mm bores for 757 cc.  What do the guru's here have to say about this combination?  Is there a problem with using the 83mm jugs for a V7 Sport rebuild?


I am currently leaning toward option A.  As I suspected, the assembled knowledge here is united that putting chrome bores back in service is a really bad idea.  As several pointed out, I will have a grand or so in redoing the rest of the motor so risking that, as well as doing a half assed job, will not be my final solution.

I am still interested in the arguments for and against options A & B and any other insight and advice you can give before I start bolting things back together.

Thanks...   

[wymple]

Last I had some done at Millennium (V7 Sport, March of this year) $209.90 was retail, my cost even lower.

That's good to hear. Everytime somebody asks about chrome bores it is promoted as a 1000 dollar problem. 400 is far less scary.

[Hahnda]

That's good to hear. Everytime somebody asks about chrome bores it is promoted as a 1000 dollar problem. 400 is far less scary.

$400 does not get you new pistons, rings, piston pins, clips, head gaskets etc though.
For about $750 you can get a pair of Gilardoni kits.
It is a bit of a toss-up because sometimes you can get away with using your old pistons.

[lucian]

If your pistons are ok and your cylinders have no issues other than the chrome bores I would have them re plated.  You will keep originality and save a buck. Millennium does a first rate job. Rings and gaskets are peanuts. You could send the pistons along with the jugs and they will fit the rings for you, for a fee of course.

[Antietam Classic Cycle]

One of the problems I was facing was that Gilardoni kits are less available for the V7 (82.5mm) bore than others so I was not sure I could find them.  You have given me some other options to consider...

Option a)  replate existing bores with Nikasil (via Millennium).  I got a quote today similar to what Antietam Classic stated and did some more research on this approach.  Sounds pretty appealing -  so what are the down sides?

Option b)  I was told that a Gilardoni kit for the Ambassador will work with a V7 -  seems V7s were 82.5 mm bores for something like 748cc and Ambos were 83mm bores for 757 cc.  What do the guru's here have to say about this combination?  Is there a problem with using the 83mm jugs for a V7 Sport rebuild?


I am currently leaning toward option A.  As I suspected, the assembled knowledge here is united that putting chrome bores back in service is a really bad idea.  As several pointed out, I will have a grand or so in redoing the rest of the motor so risking that, as well as doing a half assed job, will not be my final solution.

I am still interested in the arguments for and against options A & B and any other insight and advice you can give before I start bolting things back together.

Thanks...   

I've heard from a reliable source, that when the next batch of Gilardonis become available, V7 Sport sets will once again be among them. Probably 3-4 months away would be my guess.

The only real downside to option a) is your used pistons. Measure them carefully, especially the ring grooves, and compare those to the specs. in the factory manual. If any are out of spec. then I wouldn't reuse the pistons.

Option b) downside would be a slightly lower compression ratio - 9.2 to 1 vs. 9.6 to 1 originally. Will it make enough difference to even notice? On a dyno, maybe, but in real world use - I doubt it. I've gone the other way - V7 Sport cylinder kits on an Ambo. Didn't notice any difference other than perhaps slightly more low-end power. Could have been my imagination.

[Perazzimx14]

I had a set of cylinders re-plated last winter because Gilardoni's were not available. Until it was all said and done being able to reuse my pistons and wristpins including, new rings, circlips and shipping the cylinders to and from the plater the total monetary difference was I save about $20.

Had Gilardoni kits been available and even if they were several hundred dollars more I would have got them. Two other projects did get Gilardoni's. I have no issue with the quality of the platers work and would use them again if I find myself in the same situation. But when kits are available that the way to go. 

[Markcarovilli]

I had a set of cylinders re-plated last winter because Gilardoni's were not available. Until it was all said and done being able to reuse my pistons and wristpins including, new rings, circlips and shipping the cylinders to and from the plater the total monetary difference was I save about $20.

Had Gilardoni kits been available and even if they were several hundred dollars more I would have got them. Two other projects did get Gilardoni's. I have no issue with the quality of the platers work and would use them again if I find myself in the same situation. But when kits are available that the way to go. 

:1:
did same and feel the same....

Mark

[Roebling3]

You might check with Greg Bender @thisoldtractor.com  He has used barrels. Perhaps something that will work. My only experience on the subject is with plating peeling in bmw cylinders; late 70's, 2xR65.  R3~ 

[Antietam Classic Cycle]

You might check with Greg Bender @thisoldtractor.com  He has used barrels. Perhaps something that will work. My only experience on the subject is with plating peeling in bmw cylinders; late 70's, 2xR65.  R3~

  Greg has used barrels that have already been replated in Nikasil. If you can find (or have) good matching pistons, that might be a good way to go. Check them out here:
http://www.thisoldtractor.com/for_sale_moto_guzzi_parts.html

[motogman]

Parts are at the machine shop getting cleaned, heads done, etc.

I think the pistons are fine but will measure when I get the parts back - hopefully next week.

Unless the pistons are out I will send them with the bores to Millenium to get the bores done.  I like the idea of keeping the original bits.

[Chuck in Indiana]

I like the idea of keeping the original bits.

this

[Perazzimx14]

Parts are at the machine shop getting cleaned, heads done, etc.

I think the pistons are fine but will measure when I get the parts back - hopefully next week.

Unless the pistons are out I will send them with the bores to Millenium to get the bores done.  I like the idea of keeping the original bits.

But if you re-plate them they are no longer original.

[motogman]

But if you re-plate them they are no longer original.

I have already repainted some bits, changed the air in the tires, and fixed some broken wires so I guess I am over the original cliff already.