Not sure what happened to my previous post on this, but for some reason I can't call it up anymore.  Thanks for the replies on this topic so far.   I made a mistake describing the issue initially.  The issue is what I believe is a leak on the left side of the drive axle.   I recently replaced all the oil seals/gaskets and the leak is not coming from the side cover gaskets or transmission case from what I can tell.

On the transmission parts diagram the leak appears to be is coming from the #26/27 area.   

Yamaha Motorcycle 1972 OEM Parts Diagram for TRANSMISSION | Partzilla.com

As I tried to pin the location down, I notice that I did not set the lock washer, which make me think I may not have torqued the nut on this side as well.   Unlike the crank right side which has an o’ring under the collar bushing this left side drive axle side collar does not.   As well MarkT pointed our that the crank side oring is more a precautionary piece as the oil would simply flow to the clutch side anyway and not leak out of the engine. Is it possible that the leak is coming from between the drive axle #13 and the collar #27?  Unless I damage the oil seal on assembly the current seal is a new one.   Also, would not torquing #30 properly possibly be the problem?  in addition, I used the old lock washer which is a bit beat up and is it possible that need to be replaced?  When you torque nut #30 it would essentially make the drive axle, bearing inner brace, oil seal collar, sprocket, lock washer and nut a complete solid piece.  

I plan to take the cover off on this side and have a closer look as was previously suggested.  I will wipe it off and try to make sure I have the exact spot, but these are my initial findings.  Any thoughts to help me narrow this down or what I might have missed would be appreciated.

Thanks  Luke

Sorry again.  In the previous post I refer to "o'ring" and I meant oil seal may have been damaged on assembly. 

Another question for those who are more tech savvy on this site, how do I insert a picture of the parts diagram I am referring to versus a link?   I tried to do a screen scrap and that may have been why my previous post failed....  Not sure.

I'm not sure what you're quoting me on but the the crank collar o-ring is very important not just a "precaution" as a leak "would just end up in the transmission"!

Crankcase only has the oil mixed with the gas.  Crankcase must be pressure and vaccum sealed and a crankshaft seal leak (or collar o-ring leak) is not an annoyance, it's very bad for the engine.

Perhaps someone else said something?  Or what I said was misunderstood?  I can't see your other threads either and can't find what you're quoting in my post history.

To post a diagram you must save the diagram (or screenshot) to your device as a photo and then attach the photo.

Posting pictures of your leak would be helpful too...  and first thing to always check on a trans leak in my experience is make sure the transmission vent hose is not plugged up.

If you've ridden it without torquing nut #30 at least a little bit, it'll leak. You can guess how I know...

Boy I feel like I really messed up this post.   You are correct MarkT I was not quoting you and I did not get the quote right rather it was "it won't be from that Oring if number 18. 18 is just a precautionary Oring to stop the possibility of oil creeping from the trans into the crankcase".   

I think the thing to do next for me is take the cover off have a better look at it and if not torqued, do that (thanks Darinm for sharing your experience) and check the vent hose is not plugged and see where that goes.

Great to have this discussion and everytime I venture out with a question I learn at least two or three other things I didnt know before.  Will be great if one day I know enough to actually be able to help others like some of the more seasoned folks out there.  This site is such a great thing to have for anyone who really likes these bikes.

Thanks again to everyone....Cheers Luke.

So you are saying you learn what it is you didn't know that you don't know? Me, too! Still...after ten years here.

Yupp!  If I knew it, then I couldn't learn it so it's only what didnt know that I am learning.   

As a follow-up to one of these things I didn't know regarding the minor leak I found out that I forgot to put the gasket on the plastic cover for the shifting cam.  I think that is were the oil leak was coming from.   Also, I torqued the drive axle nut and that may have helped as well.    

Discovered a new issue and I think the thread on the drive axle is stripping so not sure if I can have that rethreaded to a different size?  May have to get a machine shop to help me with that one.  I think it is OK for now, but it looks like it will need to be rescued sometime soon.

Two CT2s came to me in a series of bins totally apart and a couple of frames.  The guy was going to take it all to the landfill!  Lucky I convinced him to take it to me instead and I paid him for his trouble.  I have to admit I was not sure I made a good move as I wasn't sure I could get at least one up and running.  Never done anything like this before.  Got it to run the other day and today and it sounds very clean.  Hope it lasts.   I started out having no clue how to put it together, but between this site and all the great answers to my questions, the shop manual I managed to get one up and running.  I wanted to make sure I got at least one running before rebuilt the rest of it.   Looks like now I can finish it off with some paint, cables and a new seat.  So stoked to be able to do this!!

Thanks again for all the help and I am going to try to help others with what I have learned and be honest with what I don't know, which is still a lot....  

Luke 

As well MarkT pointed out that the crank side oring is more a precautionary piece. Wasn't MarkT--was 'me' i think.

Ok, i'd better admit to being the "Baddy". I did say 'that' up there somewhere but better 'withdraw that 'comment'. I still stand by the fact that 'nothing' theoretically should get along under the spacer 'providing' surfaces are flat & crank nut tight. Bearing sits square against crank web & spacer against the bearing. Ok Bad call & theoretical only. I've never left an Oring out but don't think i've replaced one either but the ones i've had in bits have had tension on it when sliding the spacer on.

I can't say that I've ever replaced a crank sleeve o-ring either...  if I'm concerned I smear a little Yamabond on the end of the sleeve hoping it will seal to the crank...  but don't do what I do...  if you get sealer inside the spacer it will be almost impossible to remove next time... and you don't want sealer to get inside the new seal either so I install seal after sleeve if using sealer...  again, not worth trying.