short of fuel starting Sr500

Hi Raggy and welcome to the forum!

The vacuum line from tap to inlet manifold should definitely not have fuel in it but if you have checked the diaphragm then you should be fine. Use a clear tube in its place to check for presence of fuel in the vac line. That line uses the pulses from the piston to operate the petrol tap.  (Safety feature.)

If you can be sure the tap is not the issue then maybe the carb is the next place to look. Maybe you could give us a quick run down of what carb/air filter/exhaust set up you have. That would guide some hopefully useful responses for you.  

One thought occurs: If the inlet manifold hasn't been renewed in a while it's likely the culprit and you're getting too much air. They live a tough life bolted to the cylinder and replacement every few years is the norm but often overlooked. The metal parts company with the rubber.

Japanese imports (if fitted with original carb, usually a BST34 CV) are set to run very lean so the set up of the carb is critical. Anything else that messes with that, like a manky inlet manifold, will cause issues  similar to yours.

Thanks for the advice, the pipe to the inlet manifold is clear with no sight of fuel in it, i will check to see the make of carb, it has standard air filter but a short silencer from webike  Japan. The bike seems to smell of fuel but when i take the plug out its only just wet slightly, certainly not flooded. Thanks again. Raggy

Sorry to spam you with replies, but your situation sounds like mine when I first got my bike. Given the JDM models are set to run lean, the apparent lack of fuel on the plug may be a red herring. More likely some other factor(s). 

Already mentioned pilot fuel screw, tank cap vent, inlet manifold and float. Have you checked the pulse coil air gap? A critical setting for reliable easy starting. Also your shorty silencer is probably not helping as you won't be getting the same back pressure you would be with the standard silencer (assuming everything else is standard.)

I had a stainless downpipe that was effectively a big bore pipe compared to the twin skinned original and I needed to add a torque cone to achieve the right back pressure. Once I'd done that (and got all the other settings right) my starting woes were all in the past.

Again, sorry to bombard you but hopefully your solution lies somewhere in the above info. (My bike was an import too and needed going right through to get sorted. But once sorted has never failed me.)

Pics needed then at this point.....