Connecting rod play/slop

[gergstuff]

Hello,

I have a 1973 850 Eldorado LAPD that developed a knock in the right cylinder. I pulled the head and cylinder and found an excessive amount of play with the connecting rod on the big end, it will wiggle a visible amount in any direction and that ain't right. The left side seems to be fine.

I took the rod out and the bearings showed some scratches in the center but not much wear elsewhere. The bike has 88,000 miles on it. I do not know if someone has been in there previously.

It would appear I found the cause of the knock but not sure how to go about fixing it.

The crank journal doesn't appear to be damaged.

The bearing shell is stamped with 4473 and what looks like a "T" stamped over an "R" followed by 20 on one end and the other end looks like 000RA. Would these be original bearings?

Does the 20 reference 20 thousandths?

I guess I will have to measure the crank journal and bearings to see if I can go one size up to take up the play?

I will check the big end of the rod for roundness as soon as I can find my tools to do so.

Any advise for trying to make it all better short of tearing the whole engine apart and starting from scratch?

Thank you in advance!

Craig

 

[john zibell]

As you said you need to use a micrometer to get the dimension of the crankshaft journal. Then call a Guzzi dealer to get the correct size insert bearings. I do recommend using a ling time dealer that is familiar with the older models. Also I suggest renewing bot big ends at the same time, and it wouldn't hurt to do the rings too. To me that insert looks pretty well shot. Can you provide pictures of the journal?

 

[scottmastrocinque]

That plain bearing is toast to my eyes.

I’m with John and am really interested in the crank journal condition photo.

If there is this much traumatic scoring on the plain bearing surface, what is there on the crankshaft journal itself?

You did state that there was motion in all directions on the right hand rod…right?

What I am most troubled by is what happened on this end of the bearing carrier?

 

[Amboman]

The Eldorado and others of that era have no oil filter, but do have a sludge trap in the crank. Mostly likely your sludge trap is at least 1/4 full which is enough to block the oil feed holes to the rod bearings. To clean the sludge trap requires the engine be torn completely down. If you plan to keep this bike and ride it, then it's in your own best interest to do the job right and disassemble it to inspect everything.

If the engine still has the original chrome-plated cylinder bores, then you'll definitely want to do a full tear-down. Flakes from the chrome bores can destroy just about everything - crank, bearings, oil pump - even the camshaft and engine case if left go long enough.

 

[gergstuff]

Well, none of that is good news...I was actually planning on selling the bike and this will kinda put a dent in value. My initial assessment of the crank journal was wrong. See attached photos, not sure if a polish will get the job done or if it needs to be turned or I need a new crank-I'm not an expert in any of this. The cylinders do not appear to have chromed bores unless all the chrome is already gone. If anyone had to guess, how much in parts am I looking at here to make it all right? I can do the labor on tear down and re-assembly. Would have to find a machine shop that can handle the crank if I don't need a new one.

 

[gergstuff]

That plain bearing is toast to my eyes.

I’m with John and am really interested in the crank journal condition photo.

If there is this much traumatic scoring on the plain bearing surface, what is there on the crankshaft journal itself?

You did state that there was motion in all directions on the right hand rod…right?

What I am most troubled by is what happened on this end of the bearing carrier?

View attachment 24781

View attachment 24782

Scott, what are you seeing there that is distressing you? Looks like maybe someone did some grinding on that end? Or maybe someone hit it with a hammer? (was not me I swear!)

 

[john zibell]

Well, none of that is good news...I was actually planning on selling the bike and this will kinda put a dent in value. My initial assessment of the crank journal was wrong. See attached photos, not sure if a polish will get the job done or if it needs to be turned or I need a new crank-I'm not an expert in any of this. The cylinders do not appear to have chromed bores unless all the chrome is already gone. If anyone had to guess, how much in parts am I looking at here to make it all right? I can do the labor on tear down and re-assembly. Would have to find a machine shop that can handle the crank if I don't need a new one.

Looks like you need to go to the full tear down. A machine shop is needed just to polish the crank if that is all it takes. Do get a new plug for the crankshaft and remember to stake it after you clean everything out and install the new plug. You aren't that far from Houston as the guys at MPH can help you as needed.

 

[scottmastrocinque]

Scott, what are you seeing there that is distressing you? Looks like maybe someone did some grinding on that end? Or maybe someone hit it with a hammer? (was not me I swear!)

I wasn’t sure but those large imperfections should not be there. I was hoping the the big end bolt hadn’t pulled loose on that side and somehow caused that.

You’ve got the best guys available (Ambomann and John Zibell) for this old stuff and I would follow their advice with 100% confidence.

 

[gergstuff]

Uff da (Norwegian expression of dismay)...now I have to figure out the cost benefit analysis of tearing it apart and fixing it and selling it versus just selling it as a parts bike. I see some nicely restored examples of this selling for big money but this is far from that. It was a well patinaed rider. Sounds like I will have to throw a few thousand at it to make it right to sell for? Versus trying to sell as a parts bike for $1000ish? Any wisdom anyone can impart here? Thanks for all the input it is appreciated.
Craig

 

[scottmastrocinque]

Everybody thinks what they have is worth $$$$$. A tiny few might be but most are not.

This “VERY CLEAN AND LOW MILEAGE” one sold for less than 6k just a couple years ago.

Most people shopping for this era motorcycle, understand or they should, that unless these have been fully restored, then you are looking at thousands upon thousands of dollars in restoration expenses.

Sight unseen, if it is good and clean otherwise, “As Is”, I think you’ve probably got a $2,500 - $3,500 project bike but that’s my estimation. Others may be different.

If it is ROUGH. Then $1,500 - $2,500.

Hope this helps you out someway.

 

[gergstuff]

Everybody thinks what they have is worth $$$$$. A tiny few might be busy most are not.

This “VERY CLEAN AND LOW MILEAGE” one sold for less than 6k just a couple years ago.

Most people shopping for this era motorcycle, understand of they should, that unless these have been fully restored, then you are looking at thousands upon thousands of dollars in restoration expenses.

Sight unseen, if it is good and clean otherwise, “As Is”, I think you’ve probably got a $2,500 - $3,500 project bike but that’s my estimation. Others may be different.

If it is ROUGH. Then $1,500 - $2,500.

Hope this helps you out someway.


View attachment 24794

Thanks Scott, this one is not rough but it certainly isn't very clean and low mileage either. I guess this gives me a rough idea. I will have to price the items I think I will need to tear it down and fix it versus just letting it go. I, like many others really don't need any more projects to add to my to do list.

 

[john zibell]

Pair of Gilardoni cylinders and pistons are $816.00 plus shipping from MG cycle. Add to that the crank work machining and your labor to start to base you expense. A running bike will bring more money that a parts bike, but you have to consider return on investment.

 

[gergstuff]

I don't think the economics on it work in my favor no matter which way I go. Will have to mull it over, maybe just keep it since it was my dream bike since I was 10 years old I can find time to work on it when I retire next year.

 

[john zibell]

I don't think the economics on it work in my favor no matter which way I go. Will have to mull it over, maybe just keep it since it was my dream bike since I was 10 years old I can find time to work on it when I retire next year.

If you are going to keep it and ride it then the investment will be worth it. I restored a Model T Ford some years ago. I can never get out monetarily what I put into it, but I've been enjoying it for the last 10 years and will continue to do so for as long as I can.

 

[scottmastrocinque]

I don't think the economics on it work in my favor no matter which way I go. Will have to mull it over, maybe just keep it since it was my dream bike since I was 10 years old I can find time to work on it when I retire next year.

Vintage motorcycles are never a “make money” type situation in my experience. They are always a labor of love and an investment in your happiness.

That being said…

The money I have spent in my lifetime, on vintage equipment, has always been offset entirely by the joy and satisfaction I experienced from the use of the motorcycle as well as the peace of mind about its running condition.

When I sold the motorcycle, I recouped most of what I had spent and the rest I chalked up to the price I paid for the “E-ticket” ride! (Old Disneyland a long long time ago reference)

Fix her. You’ll be so much better for the experience and you will grow very close to her for it.

Good Luck!

 

[Amboman]

It's easy to determine what cylinders you have: remove a spark plug, make sure the piston is down away from TDC, insert a "pencil magnet" (the stronger the better) in through the spark plug hole and touch the cylinder wall. Zero magnetic attraction = chrome, very slight = Nikasil, strong = iron liners. Even easier than that - look near the bottom outer side of the cylinders to see if the name "GILARDONI" is cast into them.

 

[gergstuff]

Thanks everyone! I appreciate the input. I will go check the cylinder I pulled off, I want to say that it is stamped GILARDONI but cannot recall off the top of my head.

 

[JasonC]

Vintage motorcycles are never a “make money” type situation in my experience. They are always a labor of love and an investment in your happiness.

This is exactly the way I feel.

I've never come close to recouping the money I've spent restoring old, mostly British, bikes. But I've thoroughly enjoyed the process and there's certainly a value associated with that enjoyment. So in my mind the restoration process was well worth it.

Jason