Topic: Crank Bearings and connecting rod markings

[BoneDigger]

Hi Everyone,

I am looking over my crank bearings and find that all five have the same stamp on them (pic 1).  Do all bearings have the same stamp?  After checking the case and crank numbering system I know that it should take two yellow and three green bearings.  I would have imagined that these two different bearings have different stamps.  Pic 2 shows some scoring on the point side bearings, so I will likely go ahead and replace all, but I wanted to check with you guys about the stamps.

A second thing I found was an interesting combination of stamps on the connecting rods.  Rather than providing a number on one side and a weight on the other like the two manuals I have indicate, my rods have both on the same side (pic 3).  The weight is a very clear "H" while below that is an etched "1" in the photo.  However, on the reverse side of the rods is etched what looks like "7/19" (photo 4).  Can anyone explain what this refers to?  All my rods have this additional etching.

[Davez134]

Is there a color marking on the sides of the bearings?

[BoneDigger]

Color on the side of the bearing? Not that I recall. I'm away from home at the moment, but will check when I get back.

[Bodi]

It looks like the mains spun in the past (can't think of anything else that would score the case journals) and were replaced, those shells don't look like OEM to me: I think whoever rebuilt the engine used USA made aftermarket parts.
Tough call now. Best approach may be to use the OEM shells suggested by the case and crank markings then plastigauge them, great if in spec but not so good if way out. There is a chance the crank was reground because of damage from the bearing seizure, and the shells are thicker than any you can get from Honda. Maybe someone here can measure the stock shell thickness and you can compare them to yours?

[BoneDigger]

So I checked for any color on the bearings and came up with none.  As suggested I plan on purchasing a full set and see how everything goes together with some plastigage.  I'll measure the thickness of the current ones against the new ones to see what the difference is as well.

Anyone know what the marks on the connecting rods mean?  Don't think they matter much at this point since the weight and the number are inscribed on one side.  I am just curious.

[Davez134]

It looks like the mains spun in the past (can't think of anything else that would score the case journals)

Just out of curiosity, why do you think the bearings were spun? The scoring in his pics looks to be on the bearing surface, not on case journal. Was just wondering if there was something I'm not seeing.

Also, curious myself about the inscribed markings on the rods .

[kmb69]

Ditto. Pretty sure if the bearings spun in the cases, they would still be stuck to the crankshaft. Do not appear to have spun to me - just the bearing surfaces are scored. You can probably measure some crank wear in the scored areas.

Your rod picture appears to me to be a 2 for the rod size under the H. Look at the rod, big end up. Pretty sure the markings on the other side are date codes. What year model is this?

[Garage_guy_chris]

heres the way a set of rods were marked in one of my engines. It seems from time to time they did some odd things during production

[BoneDigger]

Garage Guy, yeah it's pretty interesting the marks on you rods as well.  All very curious. 

As for the scoring, it is on the bearing. The cases are fine.

[BoneDigger]

Ok, so almost a year later I'm getting back to this. The bearings were the only thing scored. The case and journal surfaces were fine. I could not detect any difference in the diameter of the journal surfaces.

As for the odd etchings (7/19), I still don't know what those are. The bike is a 1972 CB750.  None of the shop books I have say what these are.