Motorcycle Repair: cb 750 seal, cb 750, chamfer

Question
I have a 74 cb 750K, do I have to split the cases to replace the primary drive sproket seal?

Answer
Bill,

if you are careful you should be able to replace it from
the outside.
Drive a pointed object into the seal to pry it out.
It may have one or two seals.

Pay attention to the way the seals are
positioned, are they flush with the case?
and watch which side of the seal is to the outside.

If the case edges are sharp you may have to
chamfer or taper the edge slightly so the seal
doesn't get damaged when inserting it.
Use a small knife and gently smooth the case
edges around where the seal goes in.
Make sure it is smooth.

Lubricate the new seal on its sealing lip with motor oil and install it with a piece of pvc plastic pipe that will slide over the shaft leaving enough length sticking out to tap against, gently tap the new seal into place. The pvc should be the same size as the
outside of the seal to prevent damage.
Try to drive it in as straight as possible.
You can even try starting the seal by hand
before using the driving tool (pvc) on it.

Here is a link to a seal install
on a Yamaha but is similar:
http://www.650motorcycles.com/XSseals.html