ok thanks.Plastigauge. It looks a bit goofy but it really works to measure bearing clearance. Mic'ing takes a lot of experience to develop the right touch to be accurate.
Genuine Plastigauge - How It Works
Plastigauge how it works for measuring the clearance of a wide variety of bearings and cylinder heads.www.plastigaugeusa.com
"Live, and Learn"Now that I understand how this works, and re-reading everyones comments, my question of undersized bearings answered itself.
Are you drunk?I would not have thought a Commando engine revs fast enough to ever need a crank regrind. Especially when they always stay at home hiding in their shed, where they are safe from speed cameras.
If you measured with a caliper, get a micrometer. Your measurement are quite undersized for standard shells and if the shell and journals look good that much wear would surprise me. Also, .005" difference in the two sides is huge and very surprising. Any idea how many miles are on the bike?Got the crank separated. Cleaned out some sludge, but nothing too crazy. Journals look great. Just hit them with some polish.
The journals measure 1.739 and 1.744. The bearings I removed were stamped with 23255 lower and 25384 upper. The internet tells me that's standard size. With those journal measurements do I go undersized now? My initial guess is either .010 or .020, but not sure.
Crank Photo
Also got the cylinder torn apart.
Cylinder Photo
Great!Ok. Dropped by an engine shop. He measured 1.7499 on one journal and 1.7487 on the other. I took my used bearings with me. He used plastigauge and torqued to 25 ft-lbs and they showed .001 and .0015 on the strip. Crank was good. No scoring, no oval, and good polish. Advice was given to run a new set of standard bearings, new con rod bolts and nuts, and it will be fine.
Now that I understand how this works, and re-reading everyones comments, my question of undersized bearings answered itself.
On to the cylinder heads now.