1979 KZ 1000 St Shaftie

After a very long hiatus, this bike is running! I cleaned to carbs, lined the tank, changed the oil and added a new battery. The bike started right up. Now the problem is when I put it in to gear it wont move. The bike rolls freely and feels like it wants to go but it wont get going. Where do I start? Clutch plates? Shaft drive? Transmission? Any ideas?

What grade/type of oil used? Some of the car oils contain a friction modifier not compatable with wet plate clutches. Do you have a centerstand? If so put it up, start the engine & put into 1st gear looking for clutch slipping.

Also what tank liner did you use? Some will disolve in the gas/alcohol fuel, so be careful. This fuel mix is very nasty on rubber fuel line bits(petcock diaphrams,fuel lines & O rings).

Nice bike!

I would be more inclined to go with the clutch and wrong oil at some point in it's life.

Drain it again (including removing the filter to dump what's in there) unless you know it isn't got the friction additive in it and then put it back together and fill with something like Rotella T and a bottle of Sea Foam. Follow the instruction on the can of Sea Foam then drain, refill and see if it is any better. If so then you may need to try and decontaminate the friction discs, if not then start taking the shaft drive apart from the wheel towards the primary, inspect for proper action as you go, hopefully it won't be in the any further than that as those can be found on eBay most any day and is just a bolt on fix.

Oh and you have your 79 ST listed as 1978...

EDIT:

That bike didn't have evidence of a trailer hookup on the rear did it? If so then you might want to go straight into the clutch first.

The FSM covering '77-'79 KZ1000's includes a periodic maintenance chart requiring clutch adjustment at 5000 km intervals:

Clutch plate wear also causes the clutch to go out of adjustment. This wear causes the play between the push rod and the adjusting screw to gradually diminish until the push rod touches the adjusting screw. When this play is lost, the clutch will not engage fully, causing the clutch to slip.
NOTE: Even though the proper amount of play exists at the clutch lever, clutch lever play alone cannot be used to determine whether or not the clutch requires adjustment.

While the clutch may indeed be worn out with plates needing replacement, it isn't uncommon to overlook or be unaware of the clutch pushrod adjustment feature, especially without a manual.

Where both (1) clutch cable slack adjustment is perfect, and (2) clutch pushrod adjustment is perfect, and the clutch still slips, more suspicion is cast toward the plates being worn and needing replacement. But other things can also cause slippage, even with proper adjustments and good plates, such as glazed plates or improper oil being used in the crankcase.

Good Fortune!