What color bearing do I need?

[Colonial-Clive (yindi)]

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

[Colonial-Clive (yindi)]

Ok the number on the con rods are 2 on all 4 of them.

[Colonial-Clive (yindi)]

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.

[Trigger]

Unless it is a very early Honda (NOT 500 or 550) the con rod weight will be in Japanese

[Colonial-Clive (yindi)]

Thanks for that explanation odd job it will sink in slowly. Now to find them elusive numbers on the crank! 

[Colonial-Clive (yindi)]

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!

[Mattdgray10]

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

[Bryanj]

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

[royhall]

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.

[Colonial-Clive (yindi)]

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.

[royhall]

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?

[Colonial-Clive (yindi)]

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!!!

[royhall]

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".

[AshimotoK0]

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. 

[Colonial-Clive (yindi)]

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