SOHC.co.uk Forums > CB350/400
Honda CB400four crankcase roller bearing wear
McCabe-Thiele (Ted):
--- Quote from: Bryanj on November 11, 2021, 08:19:02 AM ---There are only 1 set of markings for mains size
--- End quote ---
So the outside diameter of all main bearings are the same the bearing colour codes just refer to the thickness / inside size /clearance of the shells.
If the crankcase is not paired with the original crank then you have to ignore the crank case codes and work off measurements only. (Edited to include case)
Bryanj:
No Ted, each crank is sized and marked, every rod is sized and marked for both hole diameter and weight the cases are measured on each hole for size anf cases marked.
I have yet to find anybody, including myself, who can measure the pins or holes with micrometers to the accuracy Honda called for.
Honda used air gauges which feed a known air pressure into a perfect sized plug or ring with holes and the amount of pressure drop is related to size of pin or hole. This method is accurat to 3rd decimal place in metric.
The shells are sized for thickness simlarly and selected to give the correct oil clearance, remember Hondas were builtwith clearances such that running in was not required, just a "bedding in" of running surfaces as Kawasaki found with the Z1000 having to rebore under warantee as people treated them too easy and bores glazed
K2-K6:
"If the crankcase is not paired with the original crank then you have to ignore the crank codes and work off measurements only."
As Bryan noted, that's not the case.
Concept is that all the bores and pins are measured at finish of production and remain valid (unless obviously worn) from then on. Those codes stay with those components for ever in the letter or numerical form Honda give them.
The compensating factor is the shells changing thickness to accommodate the different dimensions originally given. Cross reference the two components in their table and it'll give you a shell code to make up the difference in tolerances.
Scenario of using crankcase and replacing crankshaft would only change shell's designated if the original (non shell) codes changed.
McCabe-Thiele (Ted):
I am obviously getting lost here so to clarify - I thought the crank case codes were to help identify one measurement in the shell tables for the size of the mains - got that - the other axis in the tables is for the crank journal size.
If a crank case is coded say CBBC then this code is based on the main bearing holes in the crankcase being slightlt different?
If that's a yes then crankcase halves should match YES or NO?
McCabe-Thiele (Ted):
Going back to the original post I asked if there were any rotation marks on the upper half of the crankcase as this would help support that they were a matching pair.
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