Recommend Rod Bearings?

[neetones]

1969 Ambassador. Crank is still within original spec, existing bearings are standard.

What do you recommend purchasing? I'm seeing a lot of generic bearings out there. Are they any good?

[Antietam Classic Cycle]

These are the only ones I use.
https://www.mgcycle.com/index.php?main_page=product_info&cPath=68_126&products_id=1159

[John A]

1969 Ambassador. Crank is still within original spec, existing bearings are standard.

What do you recommend purchasing? I'm seeing a lot of generic bearings out there. Are they any good?

Looks like chrome specks embedded in the bearing. I’d say you caught it in time. I’d pull the crank to clean out the sludge trap and with a magnifying glass pick out any visible chrome bits from the mains and cam bearing surfaces. I use a needle . It’s a ’ feature’ of chrome plated aluminum cylinders. It eventually comes off and it’s hard so when it embeds in bearings, it grinds away. One of the reasons is that the expansion rate between the chrome and the aluminum is different so it loses its bond.

[neetones]

This engine is such a puzzle. Horribly filthy oil, pitted lifters, cam needs resurfacing, etc...but then the sludge trap is completely empty. Gilardoni cylinders.

So someone did some work in here, but they didn't go all the way.

Looks like chrome specks embedded in the bearing. I’d say you caught it in time. I’d pull the crank to clean out the sludge trap and with a magnifying glass pick out any visible chrome bits from the mains and cam bearing surfaces. I use a needle . It’s a ’ feature’ of chrome plated aluminum cylinders. It eventually comes off and it’s hard so when it embeds in bearings, it grinds away. One of the reasons is that the expansion rate between the chrome and the aluminum is different so it loses its bond.

[neetones]

So it looks like I need a crank regrind and 1st undersize bearings (rod and mains).

Anyone have a recommendation for someone who can properly grind Guzzi cranks and check clearances, etc?

Thanks!

[Antietam Classic Cycle]

So it looks like I need a crank regrind and 1st undersize bearings (rod and mains).

Anyone have a recommendation for someone who can properly grind Guzzi cranks and check clearances, etc?

Thanks!

Grind the crank to the specs. published in the factory manual, yes. It would be up to you to check clearances.
https://www.facebook.com/Griffithprecision/

https://www.thisoldtractor.com/mg_manuals/workshop_manual_700_750.pdf

[Turin]

I sent my crank to these guys for polish and balancing for lighter pistons and rods. I also used standard guzzi crank bearings.
He's a one man shop with his wife working the phones.

 https://marinecrankshaftinc.com/

 

[cliffrod]

This engine is such a puzzle. Horribly filthy oil, pitted lifters, cam needs resurfacing, etc...but then the sludge trap is completely empty. Gilardoni cylinders.

So someone did some work in here, but they didn't go all the way.

Decades ago when I was young & knew no better (and when many people thought worrying about failing chrome was overreacting)  I only did new girladoni cylinders & pistons on my bike and hit the road.    It wasn’t long before the entire engine had to be completely rebuilt, exactly like your engine needs to be rebuilt.

My btdt $.02 of advice- If you plan to keep the bike, it doesn’t matter what someone before you did or didn’t do.  Do it $$$$ all and do it right this time or don’t waste the time & money to do anything at all.

[neetones]

So it looks like I have 83mm Gilardoni cylinders but original Guzzi pistons!?

Am I good running these or do I need to source new pistons/rings?

It looks like the rings are steel/chrome and probably incorrect for the Nikasil cylinders.

[Antietam Classic Cycle]

So it looks like I have 83mm Gilardoni cylinders but original Guzzi pistons!?

Am I good running these or do I need to source new pistons/rings?

It looks like the rings are steel/chrome and probably incorrect for the Nikasil cylinders.

Is the Gilardoni name cast into them? If not, then they're likely original cylinders that have been replated.

Probably best to replace the rings.

[neetones]

Is the Gilardoni name cast into them? If not, then they're likely original cylinders that have been replated.

Probably best to replace the rings.

Gilardoni name is cast into the cylinders. Nikasil looks to be in great shape.

[Antietam Classic Cycle]

Gilardoni name is cast into the cylinders. Nikasil looks to be in great shape.

Original pistons were "Mondial", Gilardoni pistons aren't usually marked. Any name cast into the underside of yours?

[neetones]

Original pistons were "Mondial", Gilardoni pistons aren't usually marked. Any name cast into the underside of yours?

Ah, yes, the pistons are marked Mondial and Guzzi.

[Antietam Classic Cycle]

Ah, yes, the pistons are marked Mondial and Guzzi.

Odd that someone mixed o.e. pistons with aftermarket cylinders. I guessing probably because Ambassador sets haven't been available for quite some time, so they used cylinders from Eldo kits and their o.e. pistons. As long as the piston-to-cylinder clearances are correct that shouldn't be a problem.