Bottom end question

[jcor]

Cheers mates,
can someone educate me on how the Silk bottom end is sealed? I think there are o-rings used on the inside and outside of the main bearings, correct? Not sure that's correct or how the outer main bearings are sealed to preserve primary compression within the crankcase.  My goal is to obtain the bits needed for a bottom end re-seal and ideally new main bearings while I'm doing this.  Any direction on information and where I can source the necessary parts would be appreciated.

[hendred]

The outer seals are lip seals.  Look in the technical data -bearings section on this site and under crankshaft you will find the reference numbers for the two seals. You may have to search for a cross reference table to get modern equivalent numbers - found one on Google for UK numbers - may be different in the US. The bearings should be available from bearing suppliers - in the UK somebody like Simply Bearings or Bearing Boys.

Hope this helps.

Jon

[gasman]

No, your not correct, as Jon says the outer are lip seals,  the inners are two piston rings each side which fit onto the center sprocket arrangement.







If you pull the crank apart you WILL have to have new crank pins made as they will loose their interference fit. Also the crank will have to be aligned to within 1 thou on reassembly.

It is possible to split the crank by making a special tool, a short bit of allen key welded onto a strip of steel which fits between the webs and if your lucky , you can remove the center bolt. I have done this more than once as you can see by the photo. If it does not come out you will have to split the right hand web and remove the conrod. The photo shows the conversion to the 3/8 duplex chain.  Kev