How to select main bearing and connecting rod shell sizes

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RempageR1

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Hi,

I am trying to find the correct thicknesses for connecting rod and crankshaft main bearing shells but ran into an issue.

For crankshaft main bearings you need the markings on the crankshaft and the outside of the engine block. The first one no problem, the engine mount where the numbers should be are just some unreadable ingravings. A couple of sixes but not the eight numbers that should be there, two for the balancer shaft and four for the main bearings..... On the bearings themselves the colours are almost gone so it is next to impossible to make them out.

For the connecting rod same story. Numbers on crankshaft are there but the ink on connecting rods is gone. Also the colour of these shells is almost gone.

How can I get around this? Am I missing something here?

Thank you!
 
Take a picture of the numbers on the block. Note that the manual (depending on the year) isn't completely accurate on where the numbers are. You should have 6 numbers on the block (2 for the counterbalancer and 4 for the mains).

Likely your rods are 6 or 7 and crank is likely a 2 or 3.

Sean
 
Attached is a picture of a 1300 Venture 88 block, very similar to the Vmax block.

These were the numbers etched into this block. Not easy to see.

Sean said numbers on left were needed numbers. The 78 were the counter balance & 6776 were the mains.

Gary
 

Attachments

  • lower case front.JPG
    lower case front.JPG
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Hi,

Thanks you both! Indeed the numbers were on the other side of the lower block, on the alternator side. So please verify my findings:
- On main bearing I have: 21 2221
- On the outside of the block I have: 77 and below it 5666

The numbers on the main bearing are in the right order, so journal 1 to 4 is: 2221
The numbers on the outside of the block are in reverse order, so 1 to 4 is 6665
This leads to getting shells with sizes 4444, correct?

If so, on to the connecting rod bearings. Is there an alternative place the markings of the connecting rods are? I did take one of the shells out of the connecting rod and found it has F 780 marked on it (on the outer side). Does this mean anything?

Thank you!
 
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I don't think it will have the right conversion but if I can remember i'll check since I have pretty much all the bearings on hand. may have to email me a reminder at [email protected]

Sean
 
Hi Sean, I`ve dropped you a mail for the rod sizes, if you would check that would be great.

Also, can anyone confirm the crank size calculations i`ve made?

Thanks again!
 
Here's a spread sheet that Damon F put together for calculating those bearings.

I too was a little wary of the "numbering process" of how the numbers on the block and crank are laid out and figuring out EXACTLY which bearing journal they apply to.
With the service manual tho I think it's not too hard.

I can't swear to the correctness of this sheet but Damon is the guy who did the engine assembly video, he does know what he's doing that's for sure; But I didn't use this spreadsheet, I had Sean Morley do all my thinking for me......
 

Attachments

  • Blank_Bearing_Calculator.xls
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Here's a spread sheet that Damon F put together for calculating those bearings.

I too was a little wary of the "numbering process" of how the numbers on the block and crank are laid out and figuring out EXACTLY which bearing journal they apply to.
With the service manual tho I think it's not too hard.

I can't swear to the correctness of this sheet but Damon is the guy who did the engine assembly video, he does know what he's doing that's for sure; But I didn't use this spreadsheet, I had Sean Morley do all my thinking for me......

Hi Rusty,

Thank you for the excel sheet. In my case it seems to do the job but it is in conflict with what is stated in my Haynes manual which states:
- If the numbers on the crankcase are on the right hand (clutch) side, you read them from left to right for J1 to 4
- If the numbers on the crankcase are on the left hand (alternator) side, you read them from right to left for J1 to 4.
The excel sheet does not take the location of the crankcase numbers into account.
As this is quite critical I still would like an expert to confirm my findings.

Thank you!
 
When I replaced my main & big end bearings I did it as per Haynes.

They were checked with Plastiigauge afterwards and were they were spot on.

Suggest that you do likewise?
 
The numbers on the block and crank should read the same direction if I remember correctly (I don't even think about it much anymore.)
 
When I replaced my main & big end bearings I did it as per Haynes.

They were checked with Plastiigauge afterwards and were they were spot on.

Suggest that you do likewise?

+1 on the plastigauge use. It can eliminate a teardown in the near future.
It's well worth having as a final check.
Steve
 
I checked and the marking you noted (the stamping) is the same on all the shells. I can't remember the measurements of thickness but they are only a few tenths different.

Sean
 
There are some conventions that should be cleared up to talk about this clearly.

Yamaha convention is that when they say "left journal" they mean left from the riders point of view (POV) when he is sitting on the bike, This can be seen from the depiction of crank journals showing P1 and J1 to be on the flywheel end of the crank

If you know cylinder 1 is by your left knee then you should be able to remember that J1 and P1 are also on the left end of the crank from riders POV

J5 of the balancer shaft should also be on the left side, from riders POV, but my book doesn't really say clearly and can only be deduced from inference.

The crank stampings are always
P1, P2 left to right. And J1 thru J4 left to right

The picture in my Yamaha manual, having the numbers on the case located on the Generator/flywheel side of the bike, and showing J1 to be on the right and J4 to be on the left , when looking at the case from the front, clearly shows that the journal marking on the case can be interpeted by saying.

"The numbers stamped or engraved in the case geographically line up with the journal location in the case itself"

Journal 1 is physically located on the left (riders POV) inside the case, and is the right most of the numbers stamped on the front. "when looking from the front"

This example is from the yammy manual with the numbers on the generator side of the case.

Are y'all saying that the Haynes manual says if they are on the clutch side of the case that they are also in reverse order of the example above??? And not in geographical alignmnet with the journals themselves????

"Thank you for the excel sheet. In my case it seems to do the job but it is in conflict with what is stated in my Haynes manual which states:
- If the numbers on the crankcase are on the right hand (clutch) side, you read them from left to right for J1 to 4
- If the numbers on the crankcase are on the left hand (alternator) side, you read them from right to left for J1 to 4."




This changes everything and matters alot! I have no idea the answer tho', have never seen a Haynes manual and am trusting Sean on this one; I'm sure I have the right bearings since Sean picked 'em out but I still have to figure out where to put 'em

My stampings are on the Clutch side of the bike, I am going to need to know this myself before to long.
 
Hi,

Here are the relevant parts from the haynes manual:
shellsizes1.JPG

shellsizes2.JPG


I`ve marked where the numbers are in my case. To add to the confusion, my numbers are on the flywheel side with the balancer journal sizes above the main bearing numbers. So that option isn't even described..... The best thing I can do I think is check the current shells with plastigauge because Yamaha really messed this up....
 
I checked and the marking you noted (the stamping) is the same on all the shells. I can't remember the measurements of thickness but they are only a few tenths different.

Sean

Hi Sean,

Thank you for checking. So this leads to a dead end as well. I`ll just do the same thing and check the clearances of the current shells....

Something general:
The connecting rod cap bolts are reusable right? Does this also go for the eight big crank case bolts?

Thank you!
 
We've used all the bolts with no problems. BUT, We are starting to throw away rods that have had spun bearings now (the bolts I think are overstressed and could be replaced and reuse the repaired rod though).

Sean
 
We've used all the bolts with no problems. BUT, We are starting to throw away rods that have had spun bearings now (the bolts I think are overstressed and could be replaced and reuse the repaired rod though).

Sean

Agree as they could be rounded dramaticly - more then 0,1mm somethimes LOL

If no more then 0,02 mm then little honning and they can be usable again.
Need to remember to not recondition high numer rods cuz you will be out of bearings size.
 
Hi,

Here are the relevant parts from the haynes manual:
shellsizes1.JPG

shellsizes2.JPG


I`ve marked where the numbers are in my case. To add to the confusion, my numbers are on the flywheel side with the balancer journal sizes above the main bearing numbers. So that option isn't even described..... The best thing I can do I think is check the current shells with plastigauge because Yamaha really messed this up....

What do you think Sean??

Did Haynes screw this up, or Yamaha?

My case numbers came from the clutch side of the bike.......

I'm going to need to find the answer to this to sort my bearings out I think
 
That is the same as the OEM describes (keep in mind one picture is in the supplement and the other is in the main section).

Sean
 
Thanks Sean,

I had never noticed the pic in the supplemnt before.

My bearing numbers I gave you came from the side depicted in the supplement, the clutch side....I couldn't remember if I had told you which side they came from, and didn't know it was important at the time...
 

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