Bearing

[racerrad8]

Yes, that is correct.

Your case bearings if the case is all 5, should be green bearings.

Randy - RPM

[millosman]

Yes, that is correct.

Your case bearings if the case is all 5, should be green bearings.

Randy - RPM

Hi Randy
Thanks for your reply. I am trying to establish whether the first five digits stamped on the crank relate to the Main shells and the last four digits to the con-rod shells is correct or not?
The interpretation of these markings is described differently earlier in this thread.
What does the official Yamaha manual say?

My data:is-
Crank number 11111 1123
Con rods all stamped 4
Con rod shells I bought are 3321
IE 4-1, 4-1, 4-2, and 4-3
Brown brown black blue

Hope someone can clear this up for me. Thank you.
Andy

[CutterBill]

...posted the pic to show the text that accompanies it saying to use the first 5 digits of the crank number for Mains and the last 4 digits are for the con-rods which is contrary to the other posts in this thread.

The same info is in both my Haynes and Clymer manuals. I'd love to see what the official Yamaha manual says but I haven't been able to find it anywhere in the Yam books I've got....

From the Yamaha FSM, page 3-33: "The first 5 {A} are rod bearing journal numbers, starting with the left journal. The 4 {B} main bearing journal numbers follow in the same sequence."

However... THIS IS WRONG.

Obviously, the engine has 5 main bearings and 4 rod bearings, so the above quote doesn't make any sense. Also, the accompanying diagram shows the 5 {A} numbers going to the main journals and the 4 {B} numbers going to the rod journals. Which does make sense.

So the upshot of all of this thrashing is yes... the first 5 numbers on the crank are for the main bearings, and the last 4 numbers are for the rod bearings.

Another note: forget about trying to measure the bearing halves and determine what size they are. The difference between color codes is so small (0.0002") that you can't measure it. I'm a pretty good machinist, and even I don't have micrometers capable of measuring to that resolution. A pair of dial calipers won't do it; you would need an outside micrometer with ball ends AND capable of measuring down to that level. So if the color codes on the bearings have been wiped off, you can't tell what size they are.

One more note: It may not be obvious that you can't read the number on the crank, or the case, and just pick that size bearing. It doesn't work like that. You have to start with the case number and SUBTRACT the journal number to arrive at the proper bearing size (color code.)  Hope this helps.
Bill

[Motofun]

It's a bit of a pain but plastigage is your friend...if only for confidence.

[ZOA NOM]

Hope someone can clear this up for me. Thank you.
Andy

Where's Noel when you need him?

[CutterBill]

Where's Noel when you need him?

Excuse me?     And I thought we were friends...   

[millosman]

Thanks very much for your advice everybody. Much appreciated.


Looks like I bought the right bearings thankfully!


Onwards and Upwards. 

Cheers
Andy

[JMR]

This is actually a very accurate system Yamaha uses for sizing the bearings. The difference between bearing sizes is something like .0002"  Yeah, it's very close.
The bearings are sized from tightest (thickest) to loosest. So the #1 crank bearing and the #0 rod bearing will have the smallest clearances. The #5 crank and #4 rod will have the largest clearance on the crankshaft.
Had a Yamaha rep tell me years ago you could use the brown bearings to build every engine adn probably be OK.
I built one engine with brown crank bearings and pink rod bearings. This was a Legends car engine that recieved thorough abuse and ran fabulous.
Best bet is to go with the numbers calculated from off the case, crank, and rods. You can't go wrong. Be sure to coat them with some kind of assembly lube and oil the rod bolts before torqueing the nuts.

Mike C 

I was told the same thing years ago by a person in their race department.

[Bezmozek]

WRONG is also Clymer manual:

On top of page 153 shows for con rods same color chart as for main journals starting on pos.1
Compared to chart Arnie posted here, different colours and starting on pos.0




Luckily you can check partzilla for colour codes available and for sure Arnie is right.

[millosman]

It's a bit of a pain but plastigage is your friend...if only for confidence.

I'm struggling with this somewhat.

I've measured the con rod bearing clearances with the new shells in and they are larger than with the old ones in!
I have double-checked them.

Something is wrong. Either I am not measuring well enough which I doubt as I have repeated measurements with consistent results, or I have got the wrong size shells, so I have been going over how I selected them.

The colour stripes were not visible on the old shells except on cylinder 3 which was black.

Without colour codes on 3 of the old shells, I had to determine the correct shell sizes from the crank number which ends in 1123 and each con-rod is stamped with a 4 (amongst other characters - see photos).
So taking 1123 from 4444 gave 3321 which gives brown, brown, black, blue. Notice the black on cylinder 3 does tie up with the only old shell that had a visible colour stripe on it which was cylinder 3.

So why are my clearances no better with new shells, and are larger than the specified maximum?
My readings with new shells are close to or greater than the maximum 0.040mm. Cylinder 1 is nearer 0.050mm.
See photos.

This is not making sense to me!

The motor has 60k miles on it and has not been stripped before as far as I can tell.

Can anyone suggest what I may be doing wrong or otherwise how to proceed from here?
Many thanks,
Andy

[racerrad8]

Your numbers appear to be correct in reference to the bearing selection. Here are few points to consider.

Send a photo of the crankshaft and case numbers please. Another set of eyes can't hurt at this point.

1) I do see you have added grease to the journal. That grease is going to take up space and will compress the plasti-gage more and offer erroneous readings. The journal and bearing should be dry when using plasti-gage.
2) The FJ rods are notorious for not being round on the big end. Have you checked to ensure they are round? I never install a rod without cutting the cap & rod and honing them back to round.
3) I always align my plasti-gage at the top of the rod, inline with the beam. That way if there is any taper in the bearing at the parting edges, I don't get erroneous readings.
4) If the clearances are too great after that, then the crank is worn and requires replacement.

I too have a ball end micrometer for measuring bearings. But as Bill mentioned, it is not graduated fine enough to be able to measure the difference in the Yamaha bearings.

Randy - RPM

[millosman]

Your numbers appear to be correct in reference to the bearing selection. Here are few points to consider.

Send a photo of the crankshaft and case numbers please. Another set of eyes can't hurt at this point.

1) I do see you have added grease to the journal. That grease is going to take up space and will compress the plasti-gage more and offer erroneous readings. The journal and bearing should be dry when using plasti-gage.
2) The FJ rods are notorious for not being round on the big end. Have you checked to ensure they are round? I never install a rod without cutting the cap & rod and honing them back to round.
3) I always align my plasti-gage at the top of the rod, inline with the beam. That way if there is any taper in the bearing at the parting edges, I don't get erroneous readings.
4) If the clearances are too great after that, then the crank is worn and requires replacement.

I too have a ball end micrometer for measuring bearings. But as Bill mentioned, it is not graduated fine enough to be able to measure the difference in the Yamaha bearings.

Randy - RPM

Hi Randy, thank you so much for taking the time to offer your advice once again.
Regards your comments :-
1. My plastigage instructions say to use a blob of grease to hold it in position only. I had cleaned the journal first.
2. I haven't the means to accurately measure for roundness so I will have to get help on that one.
3. I placed the plastigage at the top of the journal with the journal at its "highest" point, ie as if at TDC.
4. Sincerely hope not!

I've attached two pics showing the vital numbers - crankcase upside down but clearly shows 55555. It certainly may benefit having another pair of eyes to check them thank you.

Are you happy that the con-rod marking photo yesterday is definitely a four? There may be room for confusion as there appear to be other digits or letters present too so I hope I picked the right one. I can't see a three anywhere so think I'm safe!

Looks like I need expert help now. Unfortunately I'm nowhere near you as I'm in the uk otherwise I would be knocking on your door!
Thanks again for all that you do to keep these fab bikes on the road.
Andy.

[JMR]

 Would have been nice if Yamaha listed the thickness of the bearings and the ID of rods and case main bores (like every other major Japanese manufacturers factory workshop manuals). Then (having the tools and ability) you could actually measure conrod/main pins and actually come up with real #'s.
I agree with what was said about the rod big ends being out of round. I have only worked with 3 sets of OEM rods but every set required a good amount of cap cutting and resizing. I run Carrillo A beams in my FJ. Plenty strong and lighter than the H beams.....best of both worlds.

[racerrad8]

Are there any numbers on the other side of the rods?

If not, then those are considered #4.


55555 4444
11111 1123
44444 3321

#4 Green main bearings are what were installed new for the main bearings

2 #3 Brown
1 #2 Black
1 #1 Blue Rod bearings are what was installed new.

When I use plastigage, everything is clean. Try eliminating the grease and see what you get.

Keep us posted on the progress.

Randy - RPM

[millosman]

Thanks everyone for your advice.

Repeated measurements with plastigage give consistent results showing conrod clearances towards the top of the permitted range.

I borrowed a bore gauge to measure the ID of the conrods to get an idea of their roundness. In the main the readings showed little deviation when compared at different positions. The maximum difference I found was 0.04mm on one rod. Two other rods showed max of 0.03m in one area. The last rod showed no discernible difference at all.

The question is, how significant are these readings? Do the rods need machining or are these readings within working tolerances?

Thanks

Andy