What color bearing do I need?

[AshimotoK0]

I have been following this thread to see how Yindi gets on in his search for the elusive markings.
Yindi, have you looked at the CB500 / 550 F SHOP MANUAL to be found in Ashimoto's Dropbox? (http://www.sohc.co.uk/index.php/topic,8884.0.html)
Around page 49 there is an explanation of the procedure; it may be of help.

Looked at that Chris and they are telling you to disregard  the code's on the crank & cases & use Plastigage, which I suppose is correct as the codes were only true at manufacture. My crank is a less than 1k VIN so may be slightly different, having said that though the manual was photod using a very early crankcase VIN . No wonder Yindi is getting confused. Sure Bryan, Oddjob or Trigger will put us right though 

I have the Haynes and Clymer manuals too but they tell you little about the markings. Different in the Cb750 manual though where they referred to the marking.

There is the MCM CB500 engine strip at the Honda service School here: but they just tell you to check that the surfaces are not scored.

http://www.sohc.co.uk/index.php/topic,10163.0.html


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[Chris400F]

You are more diligent than me Ash, I couldn't be bothered to do the screen shot of the manual!
It could be a useful one for Yindi to look at though.
His engine is a 550 and as you say the manual was put together using a 500 engine, but I can't see anything in it that says there is any difference for the 550.
Let's hope it perhaps gives Yindi some pointers in the right direction.

[AshimotoK0]

Don't want to confuse you more Yindi but here is what the 'Oracles' said in 2008 on the USA / UK SOHC forums. Bryan's is straight and to the point !

Hondaman in 2008

"Honda's clearance specs were .0008" to .0012" for new (.001" nominal), with a service limit at .0032". The bearing "clearance" from their stated charts is supposed to be based on "0", which corresponds to the nominal 0.001" clearance. If you have, for example, a .0022" physical clearance in the journal-bearing assembly, then according to Honda's method you have a [.0022" - .001" = +.0012"] "extra" clearance, which is supposed to be "0" clearance.  So, when you select a bearing from their charts, you're looking for a "0" leftover, which is an "invisible" .001". Which they accept as being .0008" to .0012".

After that's been digested.....

The "colors" of the bearing shells refer to the thickness of the shell material itself. Nominal is 1.5mm (0.05905"), but the length of the "crush zone" is varied slightly in manufacture, to make the seated bearing come out pretty close to [the ID desired + .001"], if at least close to round....

One of the things that's neglected in Honda's manuals (and I only gleaned it from a Yosh rep) was the .01mm extra case-to-case clearance "spec" for the Hondabond-like goo between the cases. What he told me, in 1973, was that Honda used 0.01mm shims between the cases to represent this clearance, then bored the cases. (This came up when my friend Jim "Chambo" Chamberlain align-bored his 130,000 mile K0 cases for his first rebuild...).

If you add the "missing" .01mm (.0004") to your case bore dimensions, things look just about right :(1.4171 + .0004) = 1.4175, for example. So, if you take:

1.4175" - (.05905" * 2) = 1.2994", and, in this instance, deduct the .0004" for goo you didn't have when you measured the cases, becomes 1.2990", just like the journals. That's the "0" number, which is supposed to leave you with "standard" clearance of .001".

The BLACK bearings will take you down .0004" on the ID size, from your present clearances, it appears. If I were doing it (like I'm about to do to my 750, next time it's apart), I'd use the BLACK at your #1 and #5, and leave the rest at the BROWN where you have them. And, break the engine in under 5000 RPM for the first 1000 miles. The outer 2 bearings on all of these engines suffer the most from torsional harmonics, making their bearings wear more. On CB750, for some reason, rod #3 often follows the same wear pattern as the crank's ends, never figured out why.   

I don't know if I've explained it very well, but this all has to do with Japanese manufacturing techniques. They all seem to accept the "tolerance" of their fitups, or processes, or whatever, as the "0" or "target" value. Then, they only speak in terms of controlling their "deviances", which are those numbers outside of the "normal" tolerances. It's a little different way of looking at the world, but once you get used to it, it's not so strange. Just don't rebuild an American engine with the Japanese tolerances....you might need some really good oil to make it turn, if you did.... "

Our own Bryan Jones in 2008

"To be honest mate i always re-build with a full set of black shells throughout and run in carefully for a couple of thousand with oil changes every 500. Honda seemed to be precise in clearances so that the motor had the clearances of an already run in motor and just needed "bedding in" before thrashing. I do know Kawasaki had a problem with Z1000 being run too carefully and burning oil---reconned they needed thrashing from new
"

[Colonial-Clive (yindi)]

Hi all and thanks for all the input this morning I used a nail brush degreaser and flushe with brake cleaner I've used higher power touch and 10x magnifier in bright sunlight and still no marks to be seen. I will keep looking but I am going too S.E.P in Kegworth. For head and bore work so will get them to measure it all up even if I find the marks on the crank just too be safe. Once again guys thanks for all the help if I crake it I will post!!

[royhall]

That's the best idea, get SEP to accurately measure them as they are now not 40 years ago, then cross reference the chart for the best shells. It really is as simple as that, your over thinking this. Simples.

[royhall]

Good point about just using black shells Oddjob wouldn't do that myself.

I usually don't measure the cases as the sizes of the bores are clearly marked on the cases and unless a shell has spun they are not going to change as they are not subject to wear. On the other hand the crank journals are subject to years of wear making the original marks irrelevant. Even Honda themselves say not to use them, as in Ash's earlier post.

They should be carefully measured for size, ovality, and uniformity across the whole journal as well as checking for surface finish and scoring.

It is possible for an experienced precision engineer to use a micrometer and slip gauges to measure the crank to one tenth of a thou as long as it's at room temperature (and you don't use a digital micrometer). It's important to use the size it actually is now, rather than a note of what it was 40 years ago.

I was able to find the marks on my last two cranks (350F & CB750K4) and, although they were close, neither of the cranks exactly matched the actual sizes to the markings.

[royhall]

I agree OddJob, money money.