Honda-SOHC
SOHC.co.uk Forums => CB500/550 => Topic started by: Colonial-Clive (yindi) on August 10, 2016, 06:04:59 PM
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Hi all I am about to embark on rebuilding my 1975 k1 USA 550 engine I am in need of the big end and crank bearing color codes. The letters on the case are, AABAA and on the crank AE. If anyone can help decipher the code table for me it would be greatly appreciated. I have tried but it just Herts me brain! Cheers folks
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Ok the number on the con rods are 2 on all 4 of them.
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I should make myself clear, I need con rod and crank main bearing and have been led to believe that the letters on the cases are what defines the main bearings.
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Unless it is a very early Honda (NOT 500 or 550) the con rod weight will be in Japanese ;)
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Thanks for that explanation odd job it will sink in slowly. Now to find them elusive numbers on the crank! :-\
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Well oddjob I have just spent a hour or so with a can of brake cleaner scrubbing and cleaning the crank in the glorious sunshine and do you think I can find them there numbers can I heck so maybe I can go for brown shells and hope it all doesn't end in tears!
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Sorry but guessing isn't the way forward I had the same problem what I did was get 1 set and some plastigauge and measure them out other wise your just asking for trouble
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If you need black and can't get them the next size is brown so whilst it would not be ideal, according to Honda, it will run for a long time.
I have built with all black shells before now and given strict instructions to run in carefully for 2-3,000 miles with frequent oil changes and all has been OK.
You have to remember that Honda built these bikes with clearances as if they had already been run in and only needed a bit of final bedding in before thrashing mercilessly.
By the same token measuring the pins does not really work as Honda used highly accurate air gauges and if you check out the manual sizes there are several grades over a small dimension
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Buy a micrometer off eBay and measure them. Then get out the table in the workshop manual and "Bingo". Don't guess you will need to be lucky to get away with it. The markings on the crank are extremely hard to see, best way I found was to wash the crank with petrol and get it under an extremely bright light and move the crank around until you spot them (a bright sunny day is best, but you will probably have to move to Spain). It's hard but you usually end up finding them. But keep in mind the markings were the size when new, I prefer to measure them as that's the size now, including wear etc. But as Bryan says they were measured very accurately so unless your used to micrometers then stick with the markings or take it to an engineering shop for them to measure them. Good luck.
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So today I got the crank measured and it goes thus,
From the stater 1.300
1.2985
1.3035
1.2995
1.2980
Bearing in mind (no pun intended) that the cases are stamped AABAA and black (A) do not exist anymore, where would you point me for the right bearings? Any help from your vast knowledge bank would be greatly appreciated.
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Can I just ask how the crank was measured as a .005" variation is unheard of on a Honda crank. The differences are usually way less than that?
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That's what the mechanic gave me. I just gather it's imperial! But could be metric? I have just found letters on the crank though which are 60117 if that means any thing. Man this is getting beyond me if my old ones weren't so knackered I would reuse them!!!
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Got you with the mechanic thing. He's probably measured them with callipers. This is precision engineering you need a machine shop/engineering company to measure it accurately. It's no coincidence they call verniers "very nears".
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That's what the mechanic gave me. I just gather it's imperial! But could be metric? I have just found letters on the crank though which are 60117 if that means any thing. Man this is getting beyond me if my old ones weren't so knackered I would reuse them!!!
Its imperial but at Bryan said it is very hard to measure unless you are a dab hand with a really good micrometer and they used 'air gauging' at the factory. Best thing is to run your finger nail across the width of the journals, any significant wear like that will show up as a ridge, even without a micrometer.
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Ok royall just as a matter of interest if the only shells we can get are color 'brown or green' what difference is knowing the crank size going to make. As I have a set of cases that are stamped BBBBB which according too DS are brown shells?
So confused now :-\ :-\ :-\
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The letters on the crankcase denote the size of the hole that the bearings sit in within the crankcase (outside of shell). You also need the size of the crank journals (inside of shell). Then you go to the table in the workshop manual and read off the colour you need. Without both sizes you cannot get the size (colour) of the shells you require. You only have half of the sizes. The etching on the crank webs denotes the size of the journals. Hope you understand, seems complicated but Its simple once you get your head round it.
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Trouble is the only numbers I can find are stencilled in ink and are 60117 on the points side of the crank?
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The letters are always there but can be very difficult to find
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The letters are always there but can be very difficult to find
Try taking a shot with a digital camera and then fiddle with the contrast/brightness settings in a photo programme. I learned this from Oddjob on here. They often become clear doing that. They will be there but hard to spot. There is also other info there too in addition to the codes you need for the 5 mains and 4 big ends, well there is on the 750 anyway..
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Photo trick not work. Has anyone got a photo of wat I am looking for?
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Sorry I was confusing marks on the webs of 750 cranks
here is a photo of my 500K0 crank .. Bryan, Oddjob and Trigger are the 500 experts on here .Mine is a very early crank but the Clymer manual shows similar.
[attachimg=1]
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Ashimoto thanks for that pic I can say without any doubt that there is nothing like that that I can find but tomorrow I will be getting the nail brush out and giving it a good old scrub, one last try.
If no luck it's off to SEP at Kegworth, may have to sell my body or the VZ 800 get more for the latter come to think of it!!
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Ashimoto thanks for that pic I can say without any doubt that there is nothing like that that I can find but tomorrow I will be getting the nail brush out and giving it a good old scrub, one last try.
If no luck it's off to SEP at Kegworth, may have to sell my body or the VZ 800 get more for the latter come to think of it!!
I remember trying to see the markings on my '69 750K0 in vain. Then someone (Oddjob or Bryan on here) said they are definitely there just keep searching and lo and behold they appeared. Dunno what Honda used to mark them but it sure doesn't come off easily. If its any consolation, its much harder to see on the 750 than my 500. On the early 750 it was done without a stamp i.e freehand and in what looks like lipstick, but obviously not.
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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.
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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
[attachimg=1]
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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.
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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
"
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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!!
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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.
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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.
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I agree OddJob, money money.