Oil Gallery Blocked, Damaged Case and Main Bearings (pictures)

[3Phase]

I bought some used engine parts that came from a low-mileage (~14K miles) 1981 XS1100LH Midnight Special that, other than disassembly for sale, has not been touched since it was made back in 1981.

I am attempting to repair the damage but cleaning and careful inspection have revealed an un-Godly amount of general stupidity and carelessness in evidence.

Main Oil Gallery Blocked Since 1981

The main oil gallery is partially blocked by a piece of metal protruding into the middle of it from the oil filter gallery.



The metal blocking the oil gallery is the lower threaded part of the casting for the Union Bolt (oil filter housing bolt). It was left there at the time of manufacture back in 1981 and no one has touched it since. Fortunately it didn't break off!




Lower Engine Case Damage During Assembly In 1981

A large, deeply scratched line goes all the way across all five main bearing cutouts in the lower half of the engine case. The scratch damaged all five lower main bearing shells. Main bearing cutout #4, the lower half of the thrust bearing, is shown.





Lower Main Bearing Shells Damaged

The ten common bearing shells.



The damage to the back side of all five main bearing shells caused by the large scratch across all five bearing cutouts in the lower engine case.



The shiny spots in a line between the black marks show that the damage penetrated through the entire bearing and raised the bearing surface enough to wear against the crankshaft journals.




Regards,

Scott

[GARTHXS]

let me know

Hey Scott I have a 80g parts bike and you are welcome to the case , this bike did run until the po bent the valves

[trbig]

Ya know... I was reading motorcycle words.. and looking at motorcycle parts... but for some reason, I felt like I was just mugged on my own computer by the Jehova Witnesses?


Tod

[dbeardslee]

Tod - at first I couldn't figure out what you were talking about (as usual ), then I went back and looked at the pictures. That's some pretty sneaky subliminal advertising 3phase.

[3Phase]

Ya know... I was reading motorcycle words.. and looking at motorcycle parts... but for some reason, I felt like I was just mugged on my own computer by the Jehova Witnesses?

Tod, Dan: No mugging intended!

Garth, thank you, I'll keep it in mind!

I'm not a Witness but their literature is on my desk. It helped support the point of view and the light to a tee. So, do you have any suggestions about how to get rid of the deep scratch across the bearing saddles? As you can see it did a real number on the lower main bearing inserts and they're in an abominable state.

FWIW I have a Yamaha connecting rod bearing kit and I've been trying to measure the bearing shells with a cheap, Chinese, 0.0001" micrometer. None of the shells appear to change by more than one half of a ten-thousandth of an inch, if that, for all the colors except Yellow. I can't imagine the main bearing shells being too much different by color and thickness from the connecting rod bearings and it appears that however much dust was in the room or how much saki Mr. Fuji drank the night before putting together this kit determined the color dabbed onto the inserts. Perhaps I need a $1,000.00 0.00001" domestically produced micrometer and not the $30.00 0.0001" micrometer from Harbor Freight? <chuckling>

I can check the main bearing oil clearance with Plastiguage but that's about it and I am at a complete and total loss as to what the different bearing colors mean in real life so, at this time, I'm going to clean and re-measure my old engine cases.

The numbers stamped on both the 'new' and old engine cases for all five main bearing saddles is #4. I am praying that I can use the 'new' crankshaft that does not have hammered connecting rod journals in my old engine case.

What all this blathering babble really means is that I can get rid of the scratch in the 'new' engine case but it will make the lower main bearing saddle microscopically larger and possibly require milling the case halves and align-honing the bearing saddles to bring them back into alignment to better than one ten-thousandth of an inch to avoid grenading the engine or having to split the case to change the main bearings every couple of hundred miles.

On the supporting literature in the photos I'll nail my colors to the mast: I don't belong to a proselytizing faith but I've done Bible study with the Witnesses, Mormons and many other denominations. I like most of them and I enjoy their company and their ideas without feeling that I or my faith is in any way endangered. Any time someone wants to discuss God and the Bible my door is open and the table clear. I try to let Matthew 15:15-20 govern my lips and my actions without regard to youth, skill, experience, longevity, faith or lack thereof. That doesn't end after Bible study.


Regards,

Scott

[TopCatGr58]

Hey Scott,

I'm a simpleton with regards to the engine bearings and such, have not had any experience splitting the cases or replacing said bearings. I have only rebuilt an old Pontiac 350 engine, put in OEM sized crank bearings, and it ran for another 20K miles before I "lost" the car!

I'm assuming that this scratch is a RAISED scratch, hence why it pressed into the bearing shells. I understand that the bearings are not very hard metal, and so you apparently need a pristine matching curved shape in the bearing case portions, so I guess just sanding it down smooth would not necessary be adequate/accurate enough??

Someone recently posted about the bearing shells and their thickness according to the color codes.
T.C.

[3Phase]

Hey Scott,

I'm a simpleton with regards to the engine bearings and such, have not had any experience splitting the cases or replacing said bearings. I have only rebuilt an old Pontiac 350 engine, put in OEM sized crank bearings, and it ran for another 20K miles before I "lost" the car!

You're not a simpleton, T.C.! I've done the same and sometimes it worked good, sometimes... not so good.

As you can see from the pictures, parts 'run in' and conform/deform to fit to one another under heat and under load. Putting in new bearings can work for a while, maybe. Putting a used crankshaft in a different block than the one in which it was run without doing the matching machine work is a risky proposition at best even with new bearings. There are no shops around here that I would trust, or could afford, to regrind a crankshaft and match the cases.

I'm assuming that this scratch is a RAISED scratch, hence why it pressed into the bearing shells. I understand that the bearings are not very hard metal, and so you apparently need a pristine matching curved shape in the bearing case portions, so I guess just sanding it down smooth would not necessary be adequate/accurate enough??

Someone set or dropped this lower case half onto a thin, raised metal edge of some kind or something with an edge was dropped onto it, like refilling the parts bin or something was dragged across it (there's a squiggle on the #2 bearing saddle, not a dent). Whatever it was, it made a valley with two slightly raised edges. Without some serious professional-type measuring tools I can't tell if it's out of round at all right now but the scratch is deep enough that if I sand it down it will definitely be out of round.

It didn't appear to be too bad when I first looked at it but because it's in the lower case half where most of the force is transmitted every time a piston fires, every minute detail is press-formed into the back of the shell and vice versa. Ink on the lower main bearing saddle can leave a mark on the back of a bearing shell and vice versa.

Someone recently posted about the bearing shells and their thickness according to the color codes.
T.C.

I've read all of them, including the ones from our friends across the pond that seem to have come to the same conclusion I have reached. Someone measured the bearing shells and found almost no measurable difference.

I did not believe it. It was not possible. Needing my own assortment of new bearing shells, I found a partial bearing kit and measured some shells.

The kit didn't have any Green shells and only one Brown but there is almost no measurable difference. The Yellow shells are the thinnest so they'd be used for the thickest crankshafts. In an even more bizarre turn of events it seems that the thinnest bearing shells, the Yellow ones, are the most popular and the most difficult to find. I don't know what's up with that.

It makes absolutely no sense that several metric boatloads of crankshafts would get larger over time so the only thing I can think of that makes any sense is that bunches of them are or were being welded up and reground back down to Yellow bearing spec!


Regards,

Scott

[petejw]

Hey Scott,
The only real accurate way of checking bearing clearances
is by installing the crank and using plastiguage to get an accurate reading.
From memory the different colours were only relevant with a new engine, being new crank and bearings, with a used crank the thickest bearing needed to be used to keep in spec and i cant remember of hand which one that is. But use plastiguage to get yourself an accurate reading of clearnces.
hope this helps.

[trbig]

Theoretically, you take the numbers stamped on the engine case and subtract the numbers stamped on the outside lobe of the crank and come up with a number. Each bearing has a number and you match these with the numbers you come up with. In this way, it wouldn't matter if you swapped cranks.

I say theoretically, because after an engine is used, there is wear to the metal parts and these original stock thicknesses go out the window. As you've found out, since there is very little difference between the bearings, get a set of blue ones (Thickest), throw them in and go. Same for the rod as the crank bearings.


Tod

[3Phase]

Hey Scott,
The only real accurate way of checking bearing clearances
is by installing the crank and using plastiguage to get an accurate reading.
From memory the different colours were only relevant with a new engine, being new crank and bearings, with a used crank the thickest bearing needed to be used to keep in spec and i cant remember of hand which one that is. But use plastiguage to get yourself an accurate reading of clearnces.
hope this helps.

Thanks, Pete!

I have 8 sets of Black main bearings and two sets of Brown to play with. It'll work or it won't; should be spectacular either way.... Tomorrow I have to get the cylinder base gasket removed, again, and get everything cleaned up, again, before I can Plastigauge.

Today I've had fun reading, writing, relaxing and planning. I am most certainly, definitely, not, not! even thinking about taking a sledgehammer to the bike and its bits and building a cheery Spring bonfire out of it in the driveway.


Regards,

Scott

[3Phase]

Dialup [HQ] Video Link Warning

I say theoretically, because after an engine is used, there is wear to the metal parts and these original stock thicknesses go out the window. As you've found out, since there is very little difference between the bearings, get a set of blue ones (Thickest), throw them in and go. Same for the rod as the crank bearings.

Yep, you know it; it'll work or it won't. I'm restarting again tomorrow -- back to zero! I don't have any Blues but... but... but I found some Three Dog Night!

Shambala




Regards,

Scott

[oseaghdha]

It almost looks like a tool drag out mark to me.

Blue it up and hone it, you wont take that much material out.

Hopefully, you are using a ball mic to measure the shells.

[petejw]

Id be carefully in honing it out, even tho not much material
is taken out, there are no oversize bearings available for these bikes and as youve already noted theres not much differences in the shell size so even taking a little off could mean the difference with it staying in spec. I cant really tell by the pics but it might be worthwhile taking it to a machine shop where they can take accurate measurements and give advise.

[BigDick]

Rather than trying to remove the entire scratch, I'd just remove the raised shoulders, the high points and try to pretend the valley of the scratch doesn't exist. Like you said, if you remove it you'll be way out of round, so remove the high point which would cause the most wear. Just one more opinion *shrug*

[petejw]

I was thinking the same thing as BigDick, with a very sharp knife you could carefully scrape away the raised area til it was flush, the alloy is fairly soft, i was able to scrape away some of the castings on the outer case when i was polishing the engine.
A closer look at the pic tho, if that scratch is deep enuff and allows oil to escape past it it could cause a loss in oil pressure especially if its the same on all journals. JAT