Hello, Every now and then when I start the bike up sometimes when its warm but mostly when the engine is cold, there is a lot of bluey smoke out of the exhaust and takes a mile or two to clear. Im not to sure if it could be the valve stem seals or something else. Also the bike bike stutters through the gears at lowish revs and seems lazy to respond could this be linked. It's had recent plugs fuel and air filters and I've tried different plug leads and coils and checked for air leaks of which there is none. Also I,ve re shimmed the exhaust valves but have one slightly loose on number 4 inlet. 
Any suggestions would be welcome please. Thanks, Steve.

First off, do a search of this forum and google.

If you are leaving it on the side-stand then this is normal behaviour.

If you are leaving it on the centre stand then it is something different.

Before you get too worried, as I said, have a search. It has been covered numerous times.

These engines are pretty bulletproof.

And the answer to stumbling - don't run at low revs.  They like to be kept above 4k - it ain't a car engine 

Regarding the smoke, wot he says.
Stumbling? Check that the three blanking plugs on the throttle bodies are where they should be.
It has been known to put one on a linkage adjuster instead of the vacuum take off.  
On that subject, did you sync the TB's after shimming the valves?
Try it with the TPS unplugged. They've been known to fill with water and give strange behaviour. It'll not do any harm to the engine unplugged.
It should pull cleanly from tick over.