Topic: Seal behind points plate - how do I get to it?

[tlbranth]

1970 CB750 K0:  I'm getting some oil in my points compartment. When I was changing points assembly I took a look at how to replace the seal back there (there has to be one). Unfortunately I don't remember what I ran into but I wasn't able to get back to where there's a seal. I seem to remember it looked like I needed to remove the skinny shaft the advancer rides on and chickened out because I could just see me bending or busting it. My shop manual shows nothing. Could someone who's done this give me a step-by-step on how to get to the seal? Thanks

[bjbuchanan]

Its a fat o-ring on the point shaft. Lock it in gear, get some vice grips and a rag around the shaft and it should come loose. I use the vice grips so I can get closer to the base, haven't sheared one yet

[flybox1]

Terry, there are two seals back there.  Remove everything and your advancer.
Might want to dry everything off in there to determine which it is.
There is one oring on your advancer shaft.  You'd have to double nut the shaft to remove it to get to the oring.
There is also a seal ON the crank. 

[kmb69]

If it is not the advancer shaft o-ring, you have to split the cases to replace the crankshaft seal. It has a lip that fits in a groove on the inside edge. This seal has to hold crank bearing pressure as the right main journal feeds the #4 rod journal.

[flybox1]

If it is not the advancer shaft o-ring, you have to split the cases to replace the crankshaft seal. It has a lip that fits in a groove on the inside edge. This seal has to hold crank bearing pressure as the right main journal feeds the #4 rod journal.

Absolutely correct.
picture above revised.

[tlbranth]

Thanks guys. So the skinny shaft unscrews? Is it a right hand thread? I won't be splitting the cases unless there's a gusher that becomes unworkable - but I'll probably replace the o-ring.

[flybox1]

yes, its right-handed.
here's a photo of it from the Yamiya site.
o-ring (6x2.3 #91301-300-000) goes there between the two ribs. 

http://www.yamiya750.com/index.php?main_page=product_info&products_id=55

[Jerry Rxman Griffin aka MuthaF'er]

Try to determine where the oil is coming from first. I'm hoping it is the o-ring but I have my doubts. That shaft will be tighter than expected.