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Yeah, I know I should get a parts book, but the engine and front loop are the only stock parts I have. Anyway, I pulled the (scored) rod bearings off today and looked at the number thereon.
The part number is easy enough to read, but is this standard size? I seem to recall there should be a "-.010" stamped on them, no? Or is the oversize contained in the part number code?

R2312M

 

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OVERsize means the rod & cap have been bored. Marking will be "+" (plus) .010, .020, etc. OUTSIDE of the shells are oversized from stock.

UNDERsize means the crank journals have been ground down. Marking will be "-" (minus) .010 .020, etc. INSIDE of the shells are undersized from stock.

Standard will either be marked "STD", or just the factory part number. One of those rare occasions when Triumph accidentally had the parts marked with the actual PART number instead of a casting number or factory code stamping.
 

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Discussion Starter #3
I did write "-" for the .010 above.

The bearing is thicker :)

My Micrometer and Vernier have wandered off somewheres.
 

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Long time ago BUMP, but did you ever find out what size these were? I'm just pulling mine apart, and have found the exact same part number (R2313M) and "logo" on my shells. No "-" or "+" markings...
 

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If there's no undersize marking on the bearing,you can take it as being standard size.
There is no substitute for measuring the crankpin diameter.If it's worn more than 0.002" below the maximum spec,you won't be using the same size bearing.
You'll be grinding the crank and using undersize bearings.
 
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