Blue Bores, a tale of woe and intrigue

[frozengoose]

When I joined Wild Guzzi a few years ago, I learned about the problem of chrome lined cylinder bores in the older (60's and 70's) Tonti Guzzis. Most commentors here strongly recommend replacing the cylinders, to the point where some say these bikes are worthless without the conversion. There were none available for years, but recently a cylinder and piston kit by Meteor came out and was recommended by Charlie “the sage of Antietam.” That was good enough for me, so ordered one from Crusty Cycle, along with gaskets and o-rings. With the help of a neighbor, was able to get the bike up on the lift table, secure it in the wheel vice, and put on a ratchet strap for extra stability. These things aren’t as easy to move around as they used to be! Surprisingly, the head and cylinders were fairly easy to remove, following the directions in the ubiquitous Haynes motorcycle manual.
 
After removing the cylinders, got out a flashlight and did a visual inspection of the cylinder bore. There was no pitting or flaking of the chrome lining, so the rest of the engine should be free of damage from ingesting chrome flakes. While that's good, then you have to wonder why there's the urgent need to replace the cylinders. Better safe than sorry, cheaper than a complete engine rebuild if the flakes did get into the wrong place, or at least that’s what I’m telling myself, now.

Then it was time to disassemble the head. Had to dig out the old valve spring compressor that I bought years ago to work on Triumphs. Fortunately, it fit the Guzzi head, but it was really hard to turn the crank to compress the springs. After wresting with it, found a short piece of pipe and slipped it over the handle on the compressor and made it a lot easier. Occasionally gave it a tap with the rubber hammer, but nothing would release until suddenly, the collets popped out with a bang. Big surprise, then had to look around to find them. One was at my feet, the other about six feet behind me, apparently it flew over my shoulder. Was pretty happy I found it and it didn't hit me in the face. So then did the other valve and springs, no drama this time, it came off just as expected. Then I noticed an odd smell, like solvent or cleaner. Kind of odd cause I hadn't used any on the engine, though it did need it. Looked all around the garage and couldn't find anything leaking or spilled, when I noticed a puddle on the floor. I touched it and it was blue paint. Now that was odd, but there was an old spray can of blue paint on the shelf there, so I picked it up and took off the cap. No, it wasn't leaking, so put it back and looked around some more. Then I stepped outside the door, didn't see anything, but when I looked back inside, I could see a very faint mist coming out near the bottom of the spray can. I picked it up could see a tiny dent and pin hole in the can. When that split collet went flying off the valve springs, it must have hit the can of paint hard enough to puncture it. While it did make a mess to clean up, I was doubly glad it didn't hit me first.

Then it was time for cleaning the cylinder head and valves. I tried using carb cleaner and a brass wire wheel on them, with only modest success, so I called a local machine shop about cleaning the parts and they said $150/hr for hot tanking and bead blasting. So for that much, being of thrifty Bohemian stock, I figured I'd do it myself. Checking ebay, I found a sonic cleaner big enough to fit one head for $120, post paid. So I ordered it and it got here in a week. Sweet. In went the head and valves, bubbling away in the sonic cleaner, and after a couple of cleanings, they looked a lot better. One head and two valves done in about half an hour. Then do the other cylinder, pull the head and valves, and the sonic cleaner doesn't work. Turn it off and on few times, nothing but the fan running, no bubbles. So I let it sit awhile, then try again, and it works. No idea why, but got the other head and valves cleaned. Had to touch up the area around the exhaust port on both heads with the sand blaster, too much carbon build-up for the cleaner, but then they were done. The problem with the sonic cleaner is a conundrum. The manual offers little help, other than a brief note that if it overheats, it automatically shuts itself off. So apparently it went into auto-shut off mode and didn't return to operating status for a while. Will deal with that problem later.
The cleaned head and valves look ok, not a professional quality job, but probably good enough to keep the old Guzzi going for a few more years.

Anyway, kind of a rambling post, now I have two questions:

There are a different number of shims under the valve springs, 2 and 1 under the exhausts and 2 and 3 under the intakes. Is this normal?

Haynes manual says to locate the piston on the con rod with the gudgeon pin before sliding the cylinder down the studs and then insert the piston. The write-up on Benders site (Roy Smiths T rebuild) says to insert piston with rings into cylinder, then slide it down the studs and insert gudgeon pin when the piston's aligned with the rod. So which way is better?












 

[Frenchfrog]

Differing amount of shims under the valve springs is normal...you have to shim to get the exact measurement as in the workshop book.This means that the amount of shims used can vary. Often overlooked when rebuilding engines.
As for the piston question both ways work but I used the method as described in the workshop manual. The barrels should have a bevel on the bottom which allows the rings to go in progressively and quite easily if you use a ring compressor.All a bit fiddly but works well. Also change the pin circlips for new ones each time.

[chuck peterson]

After checking the con rod big and small ends for oval, and straight, (likely doing this at a machine shop) have them insert the wrist pin with the correct interference fit. Attach rings..

On the bench insert pistons with con rod into cylinders, (previously wash cylinders in soapy hot water several times) careful to retain the correct orientation. Easy peasy on the bench

With the bottom of the con rod off, position base gasket and orings, then slide the con rod/piston/cylinder handful into the engine case. Push the piston down into the cylinder to expose the needed space to attach the bottom of the con rod. Very carefully torque the NEW con rod bolts. They stretch when torqued

So much easier than attaching writ pins and pushing the cylinder over the piston and rings with the conrod attached to the crank

I use a machine shop to check the con rods, like I said for ovalness (ovality?) on both ends, straight and trueness, ring gap, piston to cylinder clearance, insert the interference fit at the wrist pin, measure the NEW shell bearings, and assemble the whole mess for me but leaving the bottom off of the con rod.

Just make sure you keep the orientation marks on the piston pointing correctly. Ask me how I know…

This is sooooooo much easier to assemble than struggling with the rod attached first

I used a machine shop that rebuilds CAT diesel motors. He looks at my guzzi stuff and says, “How cute..” it was great to have him available, and I think he liked having something different to do. Side note, he had a machine that could cut the running surfaces on an 8ft crank from bulldozers…

[guzziart]

With the bottom of the con rod off, position base gasket and orings, then slide the con rod/piston/cylinder handful into the engine case. Push the piston down into the cylinder to expose the needed space to attach the bottom of the con rod. Very carefully torque the NEW con rod bolts. They stretch when torqued

So much easier than attaching writ pins and pushing the cylinder over the piston and rings with the conrod attached to the crank

I wish I woulda seen this a decade ago when I did my Eldo.  I was so used to doing it the other way with my Asian bikes that I didn't think outside of the box.

[n3303j]

I never want to disturb the relationship between the rings and the mating bore on an engine thats been run so I got comfortable pulling the wrist pin while leaving the piston in running position, then just sliding the piston/jug assembly free of the mounting studs (BMW, Ural & Guzzi).

So I ended up assembling new units with the piston in the cylinder. Easy, peasy. No need to drop oil pan or open big end bearings. Far less stuff to get confused at reassembly.

Meanwhile I'm surprised you involved a stand on the project. Bike on a center stand and you perched on an inverted 5 gallon pail puts the two of you in a perfect relationship to rebuild the top end (and parts have less distance to fall and bounce making retrieval easier).

[Dave Swanson]

25 years ago when I bought my first Guzzi, a V7 Sport, I returned home from gathering it with a flattened wallet.  My first posts on WG revolved around getting that bike on the road. 

Pete Roper immediately pinned my ears back and told me to get Gilardonis in there right away.  I knew even as a newbie back then his words carried weight, but I was broke and didn't want to spend the $600 on a set. 

Since the bike only had 900 original miles I was doubly conflicted.  I pulled the heads and saw beautiful "flawless" bores.  But when I pulled the barrels I looked at the bores under magnification and could see micro-pits.  The oil also had more of a shimmer than it should have. 

The old adage - it's not IF they will fail, but WHEN should guide you.  Good job on replacing them. 

[Moparnut72]

I am picking up an 850 T on Tuesday for not much money. It has some nice parts on it so the plan is to use the best of it and the T3 I have been resurrecting. The owner says it has chrome bores which were in good shape when he installed them a short time ago. The T3 has a supposedly rebuilt motor in it but without opening it up I am somewhat concerned as to how well. Looking in exhaust ports etc I wonder. The T3 has a 1,000 motor with steel cylinders which I think may have come from a Convert but that is not verified. It did have the heads off when I got it and everything looked ok. So since the T is a running and driving bike I may take the upper ends off the T3 and put them on the T.
kk

[n3303j]

I'd be tempted to run a compression and leak down on the T3 to verify the current components. I'd keep the ferrous bores, if serviceable, long before I put old chrome bores into a currently serviceable engine.

[Moparnut72]

Good point, easy to do. The starter is installed as well as a battery. I don't have it running yet but it cranks with what seems to be good compression. I don't have a leak down tester but I do have a compression gauge. I haven't thought too far ahead yet, need to get the other bike first. Another consideration is both bikes will have past DMV fees so I need to figure out which will be the worst. I know the T is pretty bad, the T3 is from Nevada so it is an unknown at this point. Neither has been registered for years and money grubbing California gouges pretty heavily past unpaid registrations.
kk

[Dave Swanson]

I was just looking at the starting point on my T3 California from 6 years ago today.

[frozengoose]

Thanks to all those who commented and answered my questions or had other suggestions, this place is a great source of Guzzi info. Here's a few replies, but all useful comments are appreciated.

Differing amount of shims under the valve springs is normal...you have to shim to get the exact measurement as in the workshop book.This means that the amount of shims used can vary. Often overlooked when rebuilding engines.

Seems kind of odd to have different number of shims for each valve, never saw that working on Triumphs. You'd think the spring tension would take up any slight difference in spring length, those shims are pretty thin. Does the washer go next to the head or the spring, they all fell off before I got a good look.

After checking the con rod big and small ends for oval, and straight, (likely doing this at a machine shop) have them insert the wrist pin with the correct interference fit. Attach rings..

On the bench insert pistons with con rod into cylinders, (previously wash cylinders in soapy hot water several times) careful to retain the correct orientation. Easy peasy on the bench

With the bottom of the con rod off, position base gasket and orings, then slide the con rod/piston/cylinder handful into the engine case. Push the piston down into the cylinder to expose the needed space to attach the bottom of the con rod. Very carefully torque the NEW con rod bolts. They stretch when torqued

So much easier than attaching writ pins and pushing the cylinder over the piston and rings with the conrod attached to the crank

Sounds like a good method IF the rods are off the crank. Since I didn't plan on redoing the crank and rods, they are still attached. I think I'll try the method in Benders, if it doesn't work and I can do it like in Haynes.

I never want to disturb the relationship between the rings and the mating bore on an engine thats been run so I got comfortable pulling the wrist pin while leaving the piston in running position, then just sliding the piston/jug assembly free of the mounting studs (BMW, Ural & Guzzi).

So I ended up assembling new units with the piston in the cylinder. Easy, peasy. No need to drop oil pan or open big end bearings. Far less stuff to get confused at reassembly.

Meanwhile I'm surprised you involved a stand on the project. Bike on a center stand and you perched on an inverted 5 gallon pail puts the two of you in a perfect relationship to rebuild the top end (and parts have less distance to fall and bounce making retrieval easier).

That's the way I'll do it, with the piston in the cylinder. I made some thin wood shims to hold rod centered in the spigot will cut a block of wood to hold the cylinder up while centering the piston over the con rod small end opening. Hopefully it'll slide right in.

I don't get the comment about needing a bucket to stand on. Unless you're really short, the table is adjustable to the proper working height. Here's photo the wife took when I was working on an old Triumph, no bucket needed!

25 years ago when I bought my first Guzzi, a V7 Sport, I returned home from gathering it with a flattened wallet.  My first posts on WG revolved around getting that bike on the road. 

Pete Roper immediately pinned my ears back and told me to get Gilardonis in there right away.  I knew even as a newbie back then his words carried weight, but I was broke and didn't want to spend the $600 on a set. 

Since the bike only had 900 original miles I was doubly conflicted.  I pulled the heads and saw beautiful "flawless" bores.  But when I pulled the barrels I looked at the bores under magnification and could see micro-pits.  The oil also had more of a shimmer than it should have. 

The old adage - it's not IF they will fail, but WHEN should guide you.  Good job on replacing them. 

Thanks for the atta boy. Most of the Guzzi owners that I talked to up here think it's a waste of time, especially now that the bores looked so good. I guess we'll all find out!

[n3303j]

Bucket is for sitting on, not standing on. With the Guzzi on its center stand on the floor youcan do the top end rebuild without a lift table. Cylinders are at the perfect height.

The valve spring pressure does have a specified number. The shims are installed to get the spring preload to that number.

[frozengoose]

Bucket is for sitting on, not standing on. With the Guzzi on its center stand on the floor youcan do the top end rebuild without a lift table. Cylinders are at the perfect height.

The valve spring pressure does have a specified number. The shims are installed to get the spring preload to that number.

Sitting on a bucket is really uncomfortable. The wife, bless her heart, bought me the table years ago, surprise birthday present if I remember right. At the height it's set now, I can work either standing or sitting on an adjustable stool. I prefer to stand for much of the work. I spent many years working bent over on bikes, tractors, and trucks that were parked on the floor and my bad back is at least partially due to that experience.
Thanks for the useful comment on the springs. Do the shims or washer go first against the springs? I would think washer, then shims next to the head. They fell off before I got a good look when disassembling.

[Antietam Classic Cycle]

Thanks for the useful comment on the springs. Do the shims or washer go first against the springs? I would think washer, then shims next to the head. They fell off before I got a good look when disassembling.

I'm not sure what you mean by "washer" as there is only shims and the spring seat for the inner (small) spring. Shims go on, then the seat for the inner spring, then the springs, spring retainer (compress) and then the collets.

A friend once bought new-old-stock chrome-bore cylinders and pistons from a former dealer that was selling his leftover stock at Vintage M/C Days. Perfect bores... for about 1000 miles, then flakes started showing up in the oil.

[frozengoose]

I'm not sure what you mean by "washer" as there is only shims and the spring seat for the inner (small) spring. Shims go on, then the seat for the inner spring, then the springs, spring retainer (compress) and then the collets. 

The confusion with the shims comes from the parts manual and their appearance, one is noticeably thicker, like a washer, the others wafer thin, like a shim. Also, the parts manual I have shows 2 kinds in the picture: #3 washer (13037200) and #4 shim (14037300). Looks like the washer's on the bottom, then the shim(s).

What's your method to instal the piston on the con rod, inside the cylinder first then slide it down and connect the piston to the rod or put the piston on the rod and then slide the cylinder down over it. With the studs sticking up as far as they do, it seems it might be hard to get your fingers in there to compress the rings. I don't have a ring compressor but could make one.

[chuck peterson]

The bottom of guzzi cylinders are chamfered to help you wiggle and squeeze the rings one at a time as you slide the cylinder over them…built in ring compressor. A little oil spread around will guarantee you a good time as you press the rings and they wiggle back out on the opposite side…it’s a bit of a tongue sticking between teeth affair. Orient the 3x (?) ring gaps at 120 degrees from each other

Interference fit on the pin and new clips

Don’t forget ring gap measurement and adjust. Some hot rodders will buy the next size up rings and file the gap open. No experience myself

[Antietam Classic Cycle]

The confusion with the shims comes from the parts manual and their appearance, one is noticeably thicker, like a washer, the others wafer thin, like a shim. Also, the parts manual I have shows 2 kinds in the picture: #3 washer (13037200) and #4 shim (14037300). Looks like the washer's on the bottom, then the shim(s).

What's your method to instal the piston on the con rod, inside the cylinder first then slide it down and connect the piston to the rod or put the piston on the rod and then slide the cylinder down over it. With the studs sticking up as far as they do, it seems it might be hard to get your fingers in there to compress the rings. I don't have a ring compressor but could make one.

The 1 mm thick "washer" is still a shim. https://www.mgcycle.com/index.php?main_page=product_info&products_id=346 I always install the thickest shim first. Here's an illustration from the factory manual showing spring height when installed.





I am firmly in the "install the piston into the cylinder first" camp. Install one circlip and the pin part of the way before inserting it into the cylinder. With the pistons supplied with Gilardoni kits, one can usually slide the pin the rest of the way by hand, if not, warming the piston with a heat gun will make it slide easier.

[Stretch]

Some hot rodders will buy the next size up rings and file the gap open.

If you're just honing the bores - pistons and bores are within spec - this works well.
Make sure gap is square to the bore and any resulting burrs are carefully dressed off.

Sometimes a bore is very slightly barrel-shaped, but still usable. Set the minimum ring
gap at the tightest point the ring will encounter to avoid breaking a ring.

                                                      -Stretch

[Tom H]

I use a hose clamp to compress the rings. Make sure you have all the rings covered by the hose clamp. Also the clamp should be firm against the piston, bit you can still rotate the clamp fairly easily. Then I slide the cylinder down to the clamp and then give it a good quick shove down past the rings. Undo hose clamp all the way and rotate it out between the studs.

One think that does help when you do it this way, but not required. Take 2 like 1/4" plywood blocks and fit them between the piston and the engine case on each side of the piston to hold the piston straight out of the case. Much easier to get the cylinder to slide on when the piston is held. Also, if you do it like this, you need to rotate the crank a bit to get the piston down to the block. Once cylinder is pushed down past the rings, rotate the crank back and then work the hose clamp out.

Hope this helps,
Tom

[frozengoose]

I use a hose clamp to compress the rings. Make sure you have all the rings covered by the hose clamp. Also the clamp should be firm against the piston, bit you can still rotate the clamp fairly easily. Then I slide the cylinder down to the clamp and then give it a good quick shove down past the rings. Undo hose clamp all the way and rotate it out between the studs.

One think that does help when you do it this way, but not required. Take 2 like 1/4" plywood blocks and fit them between the piston and the engine case on each side of the piston to hold the piston straight out of the case. Much easier to get the cylinder to slide on when the piston is held. Also, if you do it like this, you need to rotate the crank a bit to get the piston down to the block. Once cylinder is pushed down past the rings, rotate the crank back and then work the hose clamp out.

Hope this helps,
Tom

A while back I made a ring compressor with a hose clam and some sheet metal (press plates). All I have to do is find it! I made a couple of wood shims to hold the rod in place when I removed the original pistons. I figure to cut some blocks to hold the cylinder up while fitting piston/rod pin. Thanks for the suggestions.

[frozengoose]

So today I made the shims to hold the cylinders up. Put the piston on the rod using a 1/2" extended socket, then slid the cylinder on until it was just short of the con rod pin and it measured 2 3/8". So cut a a couple of 1/2" plywood pieces 5" long to fit between the studs and the base of the cylinder, but only one fit, so had to cut another from 3/8" to fit between the studs. I'd previously made two long thin shims to hold the con rod in place when removing the piston. Now it's ready to install the piston and cylinder. Here's a couple of photos.

Also a couple of questions:

Most of the assembly instructions say to oil the parts first. Not wanting to start an oil thread, but back in the day, I used an "assembly grease" when I rebuilt the old 650 Triumphs. What's the consensus here to use?

As far as gaskets go, again they say to use grease instead of Permatex. What do the expert rebuilders use?

[Tom H]

I'm not sure of why your using all the shims, but...Assembly lube will do just fine on the rod bearings and bushings. Generally the gaskets do not need Permatex #2 type products, though some do use it and Permatex Right Stuff. Some WD40 sprayed on the gaskets or grease is just fine. The HEAD GASKET, I would leave dry, but WD40 would be a very good choice if you want to use it.

Tom

[frozengoose]

I'm not sure of why your using all the shims, but...Assembly lube will do just fine on the rod bearings and bushings. Generally the gaskets do not need Permatex #2 type products, though some do use it and Permatex Right Stuff. Some WD40 sprayed on the gaskets or grease is just fine. The HEAD GASKET, I would leave dry, but WD40 would be a very good choice if you want to use it.

Tom

I put the long, thin shims on either side of the con rod to hold it steady when I removed the old wrist pin and piston. Just left it like that, cause I figured it'd steady the rod for replacing the new piston and cylinders. The vertical plywood shims hold the cylinder just above the opening in the piston, so you can slide the wrist pin into the piston and con rod. This is using the method that puts the piston and rings inside the cylinder before you slide it down to connect with the con rod. I guess I'll find out how it works this weekend!

[Antietam Classic Cycle]

After having one "serial leaker", I started using a light coating of Permatex Aviation on both mating surfaces at the base and head gaskets.

[Moparnut72]

When I worked on radials we would smear a very light coat of Permatex Ultra Copper on both sides of a gasket just prior to assembly. Even though radials were famous for oil leaks none of ours never left the shop with even a seep. The only parts we ever had to redo were valve covers which would be slightly warped. A quick run on the surface plate with a light grit wet and dry paper would solve the problem.
kk