Topic: Crank Journal Polishing ? What to use? Crocus Cloth?

[seebee750]

I want to polish my crankshaft journals before reinstalling with new bearings.
What is every one using.
I heard that Crocus cloth workes well?Does it come in different grades of fineness?
When would you use this? The journels are in quite nice shape.

I have done a few jornals as an experiment with jewelers rouge and a cotton cloth. Very shiny now.

[bryanj]

nothing, do not polish

[dusterdude]

nothing, do not polish

uh,why not?

[mattcb350f]

+1, I thought this was common practice.

I don't know what material he used, but my engine builder polished my crank with a hand held machine with an emery cloth like belt on it. He put the crank in the lathe and used the machine to polish the crank.

Then, shortly there after told me I need oversize bearings   
 Matt.

[Big Jay]

+1, I thought this was common practice.

I don't know what material he used, but my engine builder polished my crank with a hand held machine with an emery cloth like belt on it. He put the crank in the lathe and used the machine to polish the crank.

Then, shortly there after told me I need oversize bearings   
 Matt.

Yep.... That's what we use.

Jay

[bryanj]

If there is material on the journals or score marks they are junk and as Matt has probably found oversize (actualy called undersize as that is what the pin is) dont exist.

pollishing on cars/trucks is common practice where the grind tollerance is 1 thou but the honda total tollerance on the pin is 0.4 thou and in that are two tolerance sizes so any material removed is bad news

Now the biggest gap for shells (big hole,small pin) is 3.036 mm and the smallest is 3.008 mm so the variation is 0.028mm or 1.12 thou in which there are 4 different shell thicknesses So again ANY material removed is BAD news

[Jerry Rxman Griffin aka MuthaF'er]

Jay,

How much do you reckon you removed on mine and everyone else's when you lightened and balanced the crank and installed the Carrillo rods? Sure can't be enough to trash a crank.

Please explain the procedure to everyone so we'll all understand.

Jerry

[JLeather]

Are there really not any .010 or .020 under bearings for the crank for a CB750?  I can't believe that with all the aftermarket stuff no one makes bearings for a turned crank.

[754]

Micropolishing take almost nothing off.. it uses a fine belt., and it should be done after fluting the oil holes.

 You guys want to go fast and have stock engine life?...aint gonna happen!.. everything is a trade-off..

Re poishing with Crocus cloth.
 If you think you are going change the size of a crank by poishing yourself with this, you better have a spare lifetime.

[seebee750]

Does crocus cloth come in different grades of fineness?
 

[Jerry Rxman Griffin aka MuthaF'er]

Does crocus cloth come in different grades of fineness?
 

Yes

[mattcb350f]

If there is material on the journals or score marks they are junk and as Matt has probably found oversize (actualy called undersize as that is what the pin is) dont exist.

Ya, I'm working on a 350F.... my machinist said I would be better off if I had the crank turned with (under) sized bearings. He IS picky, or rather very good    not that I'm beyond tolerence but while I'm in there, why not do it right.

I just checked bikebandit and DSS and they both show bearings available for me... not sure about other models though  I hope there not lying or I'm up a creek! 

cheers, Matt.

[Big Jay]

754 beat me to it. Micro polishing removes nothing.

Byranj is comfusing micro polishing with sanding on the journal.


Jay