Oil leak///breather?

Have a 73 commando 750 with fresh rebuild (200) miles on it. After I returned home from a run of about 60 miles, I noticed oil leaking pretty good from the lower left side. At the beginning of the day, I drained the oil due to some wet sumping and then started Bike up. I always check for oil flow and breathing and have all that...seems like good breathing...air blowing into tank from crank breather and tank breathes to atmosphere. I then changed my oil and filter and the oil level is a “fuzz” above half between L-H. When I discovered the leak , I noticed it coming from the FELT seal in rear primary. I thought...shit! I blew a crank seal? So I drained the primary and about 10oz came out! I refilled it and started the bike and no leaking sitting at Idle which it did before. Now after more reading!,,,,‍ I don’t know if this is a fluke of some sort or an actual crank seal or maybe a clogged breather? I still have the factory unit with the foam and was wondering if that’s plugged up now...do you need the foam? I don’t want to make any drastic$$$$$ changes at this time. the bike runs great otherwise. Any ideas?

PS. crank seal looks easy to get out?...and tips on pulling it out?

TWO things you need: reed valve breather, Dyno Dave clutch rod seal.

I pulled my crank seal last week 850 mk2. I screwed a self tapping screw into the metal case of the seal, then a swift tug with some pliers and it was out. Cleaned up the crankcase and round the crank, a bit of engine oil onto the seal and then carefully pushed into position with a large tube. Much easier than it seems.

Sounds like you need to keep watching that situation. Might be a fluke.

The normal or recommended quantity of oil in the primary is 7 oz. Any chance you over filled it initially? It seems unlikely a new crank seal would leak 3 oz into the primary in 60 miles.

+1 With gortnipper.

I do not think the felt washer and sliding discs at the transmission mainshaft are oil tight. Either suffer an oil drip or take more drastic action such as installing a lip seal. There is another thread going on that subject now:


Slick

thanks For the replies As for over filling no. It does wet sump and maybe the oil overtime seeped in to the primary and finally filled up enough to leak out? I will pull cover and check the three bolts as read ina previous thread and pull breather hose and check the foam and screens for blockage. Any brand of Seal you recommend? Thanks much.

Yes the three inner cover bolts can leak and also come out completely even if new locking tabs are used. I now fit with red locktite as insurance. Bit of heat from propane flame if needed when removing next time.
My main seal blew in half from wet sumping and oil poured out felt seal to let me know.

I will look into the CNW breather. Until I save a little money, do I need that foam filter in the breather line? I also have access to a one way valve for a brake booster. Thanks.

XS650 breather. Very inexpensive, a bit more robust than a vacuum booster check valve.

Change out the crankshaft seal each and every time the primary is apart.
Yes it's usually to replace the countershaft sprocket but do it.

Did any of you gents put a bead of sealant around the out lip of the seal to help hold in place ? I’ve read on other chats some did this? It seams to me that pressing it in would be good enough.


Thanks.

@Motown1 I always use a smear of JB Weld on the end of my finger (just the original one, not the rapid set)

It's always worked for me.

Yamabond/Threebond #3

Thanks gents!