Clutch problem

Hi all, can anyone help with a problem I have with my clutch, when I return from working away for  a week or 2 when I start my bike let it warm up, I pull the clutch lever and when I engage 1st gear it jerks and stalls? If I then start it again and put it into 1st gear it works fine, is this normal for it sitting for a week or so?  Thanks. Steve. 

Sounds pretty common to me for bikes that have sat a while.  

Yes, it does seem to be a common occurrence .   I wonder why.   I’d have thought that the  oily environment in which the clutch lives would have prevented it, but it doesn’t.
Years ago, I remember the clutch on my XS Eleven was well and truly stuck after being unused for a few weeks. Fortunately, I managed to free it by using a screwdriver through the oil filler hole to pry the plates apart, whilst the clutch lever was held in.

Without knowing the history.... 
A number of things can be contributing to the issue.

First, engine oil. You need to be using an engine oil certified to JASO MA or JASO MA 1 or JASO MA2. All kinds of issues with clutch sticking, hard shifting and also clutches slipping just because of the wrong oil.

Second, improper clutch adjustment technique. 
The clutch rod actuator is a cam style actuator and the mechanics of it are really important. To properly set up the clutch, one must -
first back off the clutch cable.
Take off the cover on the left side of the engine to gain access to the clutch actuator.
Back off the adjuster screw lock nut
Turn in the actuator screw until it starts to firm up.
Back the screw out about 1/2 a turn, then lock it in place with the locknut.
Last, adjust the clutch cable as you normally would.
The whole point of doing this procedure is to give the actuator the maximum linear movement on the clutch rod to disengage the clutch.

Fourth   Clutch plate grime- If the bike sat for a long time, debris particles suspended in the dirty oil can plate out on the fiber and steel plates. Kinda looks like varnish, dull yellow sticky film. Pull the clutch plates out of the basket and clean off the steel plates with a scotchbrute pad. Dont try anything on the fiber pads or youll F*** them up. Then reassemble.

Last but not least, Clutch basket wear. Not too common, but I have seen it where the fiber plates engage with the outer basket half, the fiber plates cut notches in the basket, and this can cause the fiber plates to not disengage with the steel plates causing a clutch that won't fully disengage. Sometimes if the gouging is light, the basket can be cleaned up and reused. In most cases, by the time somebody finally figures it out, the basket is beyond redemption and has to be changed but. I haven't heard of clutch basket problems with the KZ 13's but it's something to watch for.
Hope these thoughts help  
KB

Make sure your clutch is properly adjusted pull the clutch in and put a cable tie on the lever to the handle bars and see what happens in. A few weeks . If the does not stall then you know your clutch plates are sticking

Even if clutch is adjusted properly, always, always, always before starting I put it in first gear, pull clutch in, then rock and back and forth until clutch plates free. Find neutral, start, drop into first nice and easy... no KaKlunk...