This is my writeup of polishing/sanding your crank. this helps remove minor flaws in the crank from the journals so there is less chance of contact between the bearings and journals. which will lead to more efficiency from your motor.

note: i in no way take responsibility for you messing up your crankshaft. attempt at your own risk.

the tools needed for the job:
a very long shoelace (the bigger the better)
2000 grit sandpaper ( and if you can find finer sandpaper at a local parts store, get some of that too)
measuring calipers
brake cleaner of carb cleaner,
a crankshaft,
and a razor.

first clean off your crankshaft Very, Very well with brake parts cleaner or carb and choke cleaner. this is VERY essential to getting a smooth finish.

then measure your crankshaft journals width while you let the crank dry. this will tell you how wide you want your sandpaper should be. i went about 2mm over to make sure i got had contact with the whole crank journal


once you have your sandpaper cut like so, put it face down on the crank journal. try to have sandpaper covering the whole journal. this will make it easier to get all the flaws off the crank.
then take your shoelace and wrap it around the sandpaper in a fashion like so...


pull back and forth on the showlace keeping tension on the shoelace at all times. you might feel less tension after cleaning tugging for a couple minutes. this means it's doing its job.

Before:


After:


and you've done. make sure you check and doublecheck your clearances on your block and plastigage your journal clearances, it should be very very minute but better safe than sorry..

 

nice write up essential tip thankyou i will try this procedure soon ! !

 

you can use even finer grit, i see no need tho.