I appreciate this is not quite the same thing, but some of it may be of use.

I have an Enfield Electra. On any bike I switch off the fuel about 1/4 mile from any intended long stop. Reason is the most volatile parts of the fuel evaporate first, leaving the more difficult to ignite residue. If you leave the fuel on it works like a still evaporating the easily burnable bits and gradually thickening and leaving you with a carb full of residue. With the tap closed, all it can do is eventually empty the carb body which means when you turn on the fuel gain you get mostly fresh fuel in your carb.
There is another thing, If you are using a thin modern oil, it tends to drain from the rings. I can tell on my bike because I free the clutch up using the kickstart. After the clutch is free I like to turn the motor over 2-3 times to charge the cylinder with fuel. it will then start first go either off the starter motor or kickstart. As I turn the motor over TDC a couple of times I can feel the compression increase, I think because the rings are picking oil film off the bore.

I would suggest you turn off the fuel to the carb if you can. also just drip 3-4 drops of oil down the spark plug hole before attempting to start . It could save running the battery flat.

Not sure what you can do if you have a mechanical pump, as the motor will have to turn a few times to fill the carb. Try giving it full choke if you have that control just to fire the motor, it will only need it for a few seconds.

Get a can of easy start and make sure you have a good battery..

Spray the air filter with easy start then crank it.

If it runs then it's your fueling. My DRZ had the same problem. It was down to a bad angle in the fuel line and/or a restrictive fuel filter.

It may be starting easily after you've used it because there is still residual fuel in the carbs and once it's fired a few times the suction gets it moving again.

Adding a dash of Auto "Injection cleaner" to each tankful works for me., keeps the carbs clean and seems to stop the build up of crap when the bikes are standing.

I had the same problem.
Now before I try to start it, I turn off both taps,pull the fuel line off one of them and give the pipe a good blow,pressurise the fuel pump.
Pop the line back onto the tap,turn both taps on and hit the button.
Starts first time.
Not sure if this is pointing to a problem with my pump but it sure helps starting.
Mightn't work for all but worth a try.

They all do it
 

They all seam to do it , its just the time frame thats differant, it is caused by the fuel pump becoming vapor locked and failing to prime, the fix is easy , just take the fuel pump out of the system ( it only sucks the last 1ltr out anyway) bined mine straight after coming back from the stans no problems since.

zebb

www.motoloco.eu

Sounds like you may need more battery cranking power? How old is the fitted battery?

cranking it
 

giving youself more cranking power can give you more oomff to get rid of the vapour lock. but does not get rid of the underlying problem !

Hi kentfallen just been on your web site, how do i get permission to put a link to the UKNDA i wish to support our lads

zebb

www.motoloco.eu

Quick update on this folks, I haven't been on this forum for a while.

I now turn off my fuel tap every time I park up for longer than a day or so and the issue is completely resolved, the bike fires first time every time.

Thanks everyone for your input.

Yep same as Ralph's last post.

Good to know an old dinosaur can still be helpful and sometimes the 'old' fixes still work :)