Good day everyone. Ok , 73 ct3 last time ran was 2012. I've replaced about everything, tank ,carb ,points, motor runs great. I drained oil and replaced with Spectro 4 10w40 has a MA2 on back. Now clutch is slipping. I did ride bike before oil change. Only slipping under medium acceleration.

Some basic questions:
1. Was it slipping before you changed the oil?
2. Did you adjust the clutch cable?
3. Do you have any free play at the lever?

I use type F atf cos all the MA oils have ever done for me with old clutches is cause them to slip in my experience especially because my bike is ported. I ended up putting new frictions in with type F atf

i'd buy new frictions, and throw out the rubber cushion rings in between the plates, also consider shimming the springs as they loosen, of course only do this AFTER you've adjusted the clutch lever free play etc

Nothing wrong with that oil. If the clutch is adjusted properly then the plates are toasted.

Something I see quite often in these old bikes is water in the gearbox. They get parked, the steel plates rust up and tear the hell out of the fibers next time the bike gets run. This reduces the life of a set of fiber plates to less than a tank of gas.

I would pull the side cover and take a look. On a 47 year old bike it never hurts to dig in and take stock of things.

Going to have to go in there & have a look--replace frictions. Throw out those 5 rubber rings that fit under the plates too as only make a bad situation worse. But first --i forgot-- be sure the operating bits are free & fully returning so you have clearance when lever is released.

I'd certainly check the spring measurements too, the original ones that were in my '72 CT2 were out of spec and causing the clutch to slip, even with new plates.

second the springs issue