Rod bearings ----WTF?

[randy]

OK, so I finally got my cases split after waiting for the alt rotor puller to come in, argh!

I figure while I'm in there, I might as well renew the bearings so I never (!) have to open the motor again (fingers crossed). I have full NOS sets so I figure i've got it made WROOONG!!

From everything I've read, the rod bearing sizes are supposed to be marked on the rod 4, 5 or 6. On the crank web I've got all 2's. Now here's my confusion. What the hell do these numbers mean??



All rods have a six digit number, WTF?

[randy]

One more thing, this motor has about 45K on it and the bearings are just beginning to show wear. Just minor scuffing, none have any copper showing. I'm very impressed. And happy,too!

[bikerphil]

3 is the color for brown con rod bearings. Post 22 by 3phase might help...

http://www.xs11.com/forum/showthread...d+color&page=2

[fredintoon]

- - - - I might as well renew the bearings so I never (!) have to open the motor again (fingers crossed). I have full NOS sets so I figure i've got it made WROOONG!!
From everything I've read, the rod bearing sizes are supposed to be marked on the rod 4, 5 or 6. On the crank web I've got all 2's. Now here's my confusion. What the hell do these numbers mean??

Hi Randy,
I have no idea WTF those numbers mean
(FYI, the (presumably a) photo link shows up on this reply panel but not in your post, nor on this reply to the forum; they must simply hate us, eh?)
BUT, plastigage can be your friend here to find out how your shells will fit.

[DGXSER]

Fred,

Not sure what your drinkin/smokin/snortin but share would you!! That is the second post where you do not see the posted pic and I see it perfectly in all post to the thread including the first one.

[Ivan]

I think its in the clymer or Yamaha manuals on how to decode the stampings, I have seen it once. It's been a while too, so I can't remember exactly where

[Incubus]

There's a picture?

[3Phase]

New guy on the line?

From everything I've read, the rod bearing sizes are supposed to be marked on the rod 4, 5 or 6. On the crank web I've got all 2's. Now here's my confusion. What the hell do these numbers mean??

Randy, if all of the numbers on the crank web are "2" that makes it a little easier!

All rods have a six digit number, WTF?

Your linked image doesn't show up in my browser; had to load it manually after I found the link in this reply. Hmm.

Anyway, it looks like those could be three-digit numbers -- new guy on the assembly line double-stamped "383" on the rods?

According to the book of Yamaha you subtract the appropriate number on the end of the crankshaft from first number on the connecting rod to get the number/color of the bearing insert.

If your connecting rod numbers are "383" and the crankshaft numbers are all "2":

3-2=1

You should have number 1/Blue bearing shells in there.


Regards,

Scott

[Ken Talbot]

I wonder if that number is just to help you keep the rod end caps sorted out so you can easily match each cap with its rod in case things get mixed up during tear-down and cleaning. What do the numbers look like on the other rods?

[bikerphil]

If the tolerances are in spec on the shells that are in there now, they can be re-used, or, replaced with the same color shells from your new set. If they're out of spec, go to the next larger size and re-check the clearance. Done it that way on a few bike motors, not yamaha though.

[petejw]

Hi Randy,
From what ive read so far, the numbers only matter
when the crank and bearings are new, with a used crank
theyve been using the thickest bearing which from memory
are the blue ones, you could try the blue ones first and then use plasti -guage
to find the clearance.

[randy]

Thanks, guys. I've got the platigage, but I was looking for a starting point 'cause the colors are gone form the originals. The guy who wrote the bearing selection procedure is laughing.

Ken, all the rods have a six-digit number (or two 3-digit numbers!). Some are fully legible like the one in the photo, some are partially legible.

[fredintoon]

Fred,

Not sure what your drinkin/smokin/snortin but share would you!! That is the second post where you do not see the posted pic and I see it perfectly in all post to the thread including the first one.

Hi DG,
lucky you, all I can say is, they don't show up on my screen.
If an occasional glass of wine with supper will help you, go for it. That's good for you anyway, sez so in the Bible.

[3Phase]

The guy who wrote the bearing selection procedure is laughing.

I know he's laughing because he made his money and retired years ago.

FWIW, The Book of Yamaha doesn't specify which number is considered the 'first number'. I've seen the O.E.M. bearing inserts selected two ways with rod numbers read from right to left and rod numbers read from left to right. Plastiguage showed that both ways had selected the correct bearing inserts and reading the numbers in the other direction wouldn't have worked.

What does all this mean for you with the Plastiguage at the ready and a full set of new O.E.M. bearing inserts from which to choose? It doesn't matter!

Your crankshaft numbers are all "2" and, as a palindrome, even if you use the the entire six-digit rod number or chop it in half and use either of the resulting three-digit numbers the first number is always a "3" however you read it so: 3-2=1

As everyone else has suggested in this thread, start with the thickest inserts, the number 1/Blue inserts, and check the clearances with Plastiguage.


Regards,

Scott

[blue giant]

I wonder if that number is just to help you keep the rod end caps sorted out so you can easily match each cap with its rod in case things get mixed up during tear-down and cleaning. What do the numbers look like on the other rods?

Ken is right, look at the other side for the correct numbers. I was stumped on the same thing when I rebuilt my engine 2 years ago!