Honda CB400four crankcase roller bearing wear

[McCabe-Thiele (Ted)]

There are only 1 set of markings for mains size

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.

[eem46]

Dear All, that is the tricky parts of buying a empty set of crankcase, I dont know and I cant prove they are/were a matching set. Looking at other crankcases the marks are always in the lower crankcase. By the forces?

[eem46]

Can you ever found out if a set of crankcases are matching? No secret Honda stamp?

[Bryanj]

Nope, but over many years you usually find if they aint a pair at least one of the many machined holes you will find you can feel a step at the join

[McCabe-Thiele (Ted)]

Can you ever found out if a set of crankcases are matching? No secret Honda stamp?

You raise an interesting point - Honda did a nice big clear lettering stamp on the lower crank case with no alpha/numerical marks to say this crank case top matches the crank case bottom.

In my head I find it difficult to see how a rotating bearing would not mark both halves of the crank case in a similar though not necessarily identical manner - then again you mention the forces at work - rotational from the gearbox but with the down forces at the same time from the pistons on the crank maybe that explains why the marks are mainly on the bottom half - that makes sense.

If you have seen other cases where the marks seem to be always on the bottom half then that supports your explaination.

[Bryanj]

Rod shells are always more worn on rod side not cap, it takes 3 of the 4 strokes load, never really noticed any difference on mains and as ball/roller casings are not supposed to totate in housing i have no idea

[eem46]

My 50cc Kreidler moped has special code to see of both halfs are matching. Strange that Honda leaves that ‘option’ open. Even on the picture of Julie you can see that the rollerbearing makes a mark. But ofcourse a mark or moving slighty material is different.