Topic: Camshaft holders logic and a Honda enigma

[caller]

As for a CB 750 K4
1. As far as I know, its important that the camshaft got the same bearing when reassembled. So I got two identical camshaft holders and they are indexed, RH, GH and RZ, YR. All pairs indexed from left to right. Are there any logic that makes me figure out which camshaft holder should be assembled to the alternator- or contact breakers side?

2. Why is there a special bolt  to hold one of two attachments for the oil pipe hose B, from crankcase to oil tank? On the crankcase there are four bolts that holds hose A and B. One special 90040-300-000 6x25mm and 3 regular 92000-06025 6x25mm. It looks as the special bolt got a loose washer fixed on it. The part list tells that the four bolts needs four washers.
Engineers are very accurate so there must be a good reason for the special bolt.

[evanphi]

As for a CB 750 K4
1. As far as I know, its important that the camshaft got the same bearing when reassembled. So I got two identical camshaft holders and they are indexed, RH, GH and RZ, YR. All pairs indexed from left to right. Are there any logic that makes me figure out which camshaft holder should be assembled to the alternator- or contact breakers side?

They should go in as they came out because they would be seated to the camshaft. If you put them in opposite they will just create more wear on the bearing surfaces. You should have marked them when you took them out!

[HondaMan]

If you didn't mark them at disassembly, there is a way on the post-K2 bikes to figure out which way they go: the inside bearings on the post-K3 bikes have more bearing clearance over the cam than the outer ones, by several thousandths of an inch. Typically, the outer bearings (new) had 0.0024" or so clearance while the inner ones were twice that. As the cam wears in, and due to the downward flex in the middle of the camshaft at engine speeds over 6000 RPM, the inner bearings wear more.

You will have to use either some really thick Plastigage, or bore gages and micrometers to measure this clearance. If the engine has more than, say, 20k miles on it, this clearance can be over 0.008" (like mine, at 0.010"!), but this will not hurt anything but an all-out racing engine. It was part of this engine's design, to let the center wear in over time and the forward edges of these bearings to wear in a slight egg-shape. Not to worry.

[PeWe]

Do not forget the 4 small o-rings under the cam holders. 2 of them seal the end of the oil line. Std o-rings can be too slim and almost no rubber over the head where it has contact with the cam holder.

[754]

 Actually you dont need a mic to find bigger side...  but you wont get a recordable measurement.
Use a telescoping guage to check each end, after clamping together.
 if you measure loose first, the guauge will have clearance in the other side.
 if you measure bigger first, guage will simply not go in other side..

 I tell people all the time.. measuring is not always about a number, sometime you can tell by feel.. or go..no go..

[caller]

Thx for all the answers.

I got the engine in parts  and it wasn't marked.
The O-rings are on place 

I think I solved the problem. On the left side of the camshaft a washer is mounted. This washer marked one camshaft holder I think. Only one of them got marks that could correspond with the washer.

[PeWe]

I check the inner cam bearings that has more wear as Hondaman wrote. Take photos before and under the restoration is a good idea. If the bike has been restored by a pre-owner it is not shure that the assembly was absolutely correct.

[HondaMan]

Thx for all the answers.

I got the engine in parts  and it wasn't marked.
The O-rings are on place 

I think I solved the problem. On the left side of the camshaft a washer is mounted. This washer marked one camshaft holder I think. Only one of them got marks that could correspond with the washer.

The O-rings are 1.9x5.8 size from Honda, or you can use the more common 2x6mm size as well. Once they get hard, they leak a bit.