Topic: Cb 550 crankshaft bearings.

[ClewisEMFD]

Hey all the SOHC gurus out there. I have a donor motor for my Cb project and I have completely torn this sucker down. Split the cases took the crank out and now after cleaning everything up I am ready to rebuild this thing. I need some info about the crank bearings. I made a huge boo boo when I was taking the bearings out I didnt bother to label them because I was going to replace them. I found out today that the specific Size i need (Green, Or C size according to my manual) is pretty much non-existent.

So my question is: Did I completely screw myself by not marking my original bearings? Should I have my case milled out to accommodate a larger but more readily available bearing size? Or does anyone have some spare C sized bearing out there. (I will do horrible, horrible things to get this bike running...) or can I just wedge some black sized bearing in there and just promise to be really careful while braking them in...LOL!

I am plastigaugin the bearing tonight to see if I can figure out what got where and if I even need to replace them.

[nancy]

Black? Why not? I did and many do. My K1 engine had toasted bearing shells - so I had the crank mic measured at a machine shop - empty cases, bolt bare crank down in the cases complete with (new) shells, dowels inserted - so they can measure tolerance/wear. I just bought black shells. Diff between green/yellow..black is so minor anyhow - except for a new engine I guess. I kept my crank - but machinist should mic measure journals for tolerance and advise you whether to bin it or not. Reason I went black - you have to have new shells BEFORE you can measure them in situ on the crank - using plastigauge - so I bought ONE set of two shells (black) and moved them around measuring - took a while..but proved that black was it. So bought 3 more sets. Then took it in as mentioned above - for crank checking in the cases.
Plenty of previous threads on this subject here.

Regards
Mark

[lucky]

Make sure you clean those oil passages in your crankshaft.
See the photos in the Tech Tips section of the Cycle-X website.

[ClewisEMFD]

Well the motor has long been put together....but there tech tips were not very helpful. Just showed them drilling a hole?

[bryanj]

All black shells and run it in for 1500 miles not just a 500 mile break in

[Oddjob]

Whilst I agree with the black shell advise why not just source the right shells if they available, depending on how many you need this place should help

http://www.hondarestoration.com/nosResults.asp?models=CB500-K1%2CCB500+K1-500+Four-1972

Somewhere I have a bag of shells I bought many years ago, there are approx 50 shells in the bag, mainly crank but also some rod ones, no idea where the bag is now, can't seem to locate it, just imagine how much that bag is worth today. As far as I can remember the vast majority were green and browns, the most commonly used shells.

Also some here, if 7 isn't enough http://www.cmsnl.com/ and 8 here http://www.davidsilverspares.co.uk/parts/by-part-number/partnumber_310/

[nancy]

Oddjob,
The main reason I went black was to avoid buying green, brown or yellow only to find I still had a little too much play...meaning I had to buy black anyhow.  I reasoned that the diffs between Black,....down to yellow etc were so small,..it was unlikely that black would be too fat on a well used crank and conrod. Fortunately it worked for me.
If I had access to lesser shells - I'd have used them. Here in NZ, I had to pay NZ$21 per each HALF shell.
Mark

[Oddjob]

I have to be honest here and say in all my time as a Honda mechanic I've never had to fit larger shells, the crankcase doesn't wear and the crank unless you totally abused the engine didn't show any wear.

But no harm no foul as they say, if it worked for you that's great.