Crank bearings good or bad

[Acro1985]

The crank journals look fine no wear ridges that I can see or feel just a darker line in middle of them all which matches up with the oil channel in the middle of the bearings.

The crank journals measure 33.48mm if I have read the micrometer correctly

[McCabe-Thiele (Ted)]

Are you talking mains or big ends with your measurement?
I don't have the tables to hand.
Posting your crankcase codes will help.

PS If you can only measure to 0.01 mm you will definitely need to use Plastigauge or have the crank professionally measured.

[Acro1985]

The code on the back of the case is BBBBB

The mains measure 33.48
The big end measure 35.48

I think I will look to get it professionally measured just in case I have done it wrong

[McCabe-Thiele (Ted)]

Honda work in Microns for crank clearances, have you managed to find any colour codes?

Good news is that BBBBB should mean you can find the right shells easily enough provided there is not much mains journals wear.
It's worth hunting down the shell side colour marks - out of ten shell edges you are in with a chance.

[Acro1985]

What can I clean the shell edges with, as they are dirty and don't want to damage them or wipe off any slight colour mark

[McCabe-Thiele (Ted)]

I would use Meths though petrol might be okay using a small paint brush rather than a cloth.

[Bryanj]

I doubt after this long you will get a colour from them
For new try Yamiya in Japan

[Laverda Dave]

And try using a very powerful magnifying glass, you may be lucky and see a fragment of paint colour on the edge of the shell. I have a jeweler's eye glass and it's pretty good.

[Acro1985]

I am going to take it to a machine shop and get it all measured properly as I am not confident I am doing it right and the last thing I want to do is install the wrong ones and cause more problems.

Plus from my measurements and very limited understanding of the bearing charts both the crank and big end measurements are outside of spec. Even though despite obvious wear on the big end bearings there was no obvious play in them when bolted to the crank 🤷

Thanks again for all the advice

[McCabe-Thiele (Ted)]

To compensate for wear you effectively fit thicker bearing shells.
Black is the thickest shell that is made for these old Hondas..
Assuming for the moment you crank mains are within specification.
For your mains as all the casing codes are B it probably had Green or Brown shells fitted originally in the mains.(my B coded mains were brown shells)
Finding a trace of colour would make the starting point much easier.


This photo shows a green colour code on one of my old 400 shells.
 
Main bearing shell by Macabe Thiele, on Flickr

[Murf]

Plastigauging is very easy I am sure you can do it yourself and make a good job of it. Buy a set of plastigauge, about £13, for the mains you lay the crank back in the half shells in the crank case. Then lay a strip of plastigauge across each crank journal, not around the journal. Then carefully replace each bearing cap with its half shell bearing. Torque bolts to specified torque in stages evenly across all bolts.  Remove bolts, carefully remove bearing caps, you will see a flattened piece of plastigauge on each journal, match width to those shown on plastigauge instructions. This will equate to the clearance in the bearing, check this with specifications given in workshop manual.  If in spec and bearings are visually ok, no nicks, grooving or scouring then bearings should be ok to reuse.  If not then change.  I forgot to say wipe crank journal before putting plastigauge on it but do put a thin smear of oil on half shell to stop it sticking to plastigauge strip.

If you do resort to using a machine shop to do your engine, ensure you use someone that knows what they are doing, many say they do but many haven’t got a clue.

I am just looking up the bearings for the primary shaft for when I do my engine , sizes are 22x56x16.   25x52x15, needle roller is 25x29x17, I am going to check to see if they are normal or c3 spec. Will get back on that.

[Acro1985]

The shop I am thinking of taking it to I have used before many years ago in fairness that was on a mini engine, but they have been going since the 50s and have a good reputation.

I will give the plastigauge a first though.

Let me know how you get on with the bearings

[Acro1985]

Sorry another question.

My rocker cover appears to have a piece missing near the holes for the breather. I can only seem to find ones of earlier engines will they fit mine

[McCabe-Thiele (Ted)]

That damage looks really nasty on the cam cover - have you found any of the debris anywhere yet?

I assume you are going to the machine shop to have the crank measured accurately in thousands of a mm - good move.
You will need to buy Plastigauge of the right range o.025-0.076 mm.
Quite a few videos on U-tube on the process.

[Acro1985]

No bits in the engine so I can only assume some one has run it like that 😱