SOHC.co.uk Forums > CB500/550
Crank not rotating
Oddjob:
Looks like Brown, Brown, Brown, Green to me. You can still see the colour on the side of the shell. Looking at them I suspect something wrong with the oil, loads of really small score marks like the oil had little bits in suspension. Probably not changed for ages.
Still useable though.
K2-K6:
--- Quote from: Oddjob on May 08, 2022, 08:40:19 PM ---Looks like Brown, Brown, Brown, Green to me. You can still see the colour on the side of the shell. Looking at them I suspect something wrong with the oil, loads of really small score marks like the oil had little bits in suspension. Probably not changed for ages.
Still useable though.
--- End quote ---
Yes Ken, I'd agree with your oil observations and Bryan also pointed out earlier in thread. To split it down further though, it looks like oil film breaking down and causing small parts of the shell material to stick to the crankshaft, suppose you could call that "micro seizure" with the waste going round to give score lines.
Stray particle from elsewhere in the engine or more abrasive in nature usually would get stuck in the soft shell material and cause the crankshaft itself to be scored.
So, oil film (shearing quality/consistency) below a level that can support competent bearing spacing to crankshaft. Doesn't look too drastic as you note, but a good warning to ensure oil condition/quality is high enough not to let further deterioration happen.
alexdecker:
Hey all
Alright, I have plastigauged both the crank journals and the connecting rod journals. My mind is getting slightly confused with all the numbers in relation to used bearings shells, and I was hoping to get your guidance as to how to proceed from here.
All measurements are in inches. For the crank journals, I got this (color of the existing bearing + plastigauge measurement):
1 (brown): .0019
2 (green): .0019
3 (grown): .0017
4 (green): .0019
5 (black): .0017
For the connecting rods, I got this:
1 (brown): .001
2 (brown): .0013
3: (brown): .0015
4: (green): .0013
As you can see, some of them fell in between sizes on the included measuring tape of the plastigauge, but I did my best to estimate where in between it fell.
Can anyone make sense of this math?
Seabeowner:
According to the manual, fine, but I expect someone will be along later to say they are not keen on the Honda specs.
Crank and big ends: New 0.00079 - 0.00181 Service limits 0.0031 (in inches)
Bryanj:
Sizes are just about within spec but markings on shells wory me.
I suspect fitting new of same colour would give tighter tolerance
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