Originally Posted by Triton Thrasher
Kickstart easy to press down but sometimes not turning the engine is usually breakage of the thin wide spring behind the kickstart ratchet pinion. You reach it by removing the gearbox outer cover with both pedals still on it, removing the nut on the mainshaft (check that it was tight) and pulling off the outer ratchet piece, then the ratchet pinion.
When removing the cover, keep a little downward pressure on the kickstart and try to keep the big clock spring in place.
I've had no personal experience with this, but looking at the parts diagram I tend to agree with Triton here. The thin wide springr he is talking about is actually a flat wound spring called a thackeray washer. It is probably broken or weak and when the oil is cold and thick, it is not sufficient to engage the ratchet.
I suppose the nut could have backed off, but not sure why that would only make work when warm.
Try putting the bike in gear on the center stand and turning the rear wheel to turn the tranny a bit. It might make the ratchet engage.
Check your parts book or the parts book on-line and you will see the spring. You'll have to go in there regardless so might as well pick up the required spring and have it ready.