SOHC.co.uk Forums > CB350/400

Crank Half Shell Bearing Size

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AshimotoK0:
The stamped codes on the shells  are production codes only and the coloured marks fade in a hot engine to a browny colour ( well they did on engines I have stripped). Anyway the crank markings  codes are only for an unworn crank so you need to select the correct colour codes from the charts cross referenced with the crankcase stampings and the crank markings, then Plastigage the bearing clearances after bolting everything together temporarily. Bryan or Graham etc. may be able to tell you just to use a certain colour code and run in carefully I don't know... they have built lots of engines between them. Bryan tells me you can't mike up the crank you need air gauging but on my 1st 400/4 I had the crank miked up and used the measurements  to select the shells and the clearances were spot on, when I used Plastigage. Needs a pretty good measuring man though and you need to check for ovality in the journals and measure very accurately.

We did have air gauges where I work part time but someone chucked the whole system in the skip, not knowing what the kit was used for   :(

Hope this helps ... Ash

Bryanj:
I have never seen anywhere codes that relate to the stampings on the back of the shells.

We were told way back when that Hondas were built with the clearances expected after running in and i have built several engines using all tightest tolerance shells and told the owners to "Run It In Carefully" for a couple of thousand with multiple oil /filter changes without ever having one back. When you consider that the spec to 0.01 of a mill which is less than half a thou you have to be damned good and consistent with the mic

Mr-Gear:
Well ok, Thanks for clearing it up guys. Really helped me out.

Thanks, Ryan

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