Hmmmmm... now I'm getting frustrated!

Sounds like you've been fairly thorough on the fuel side of things. Now I'm thinking electrical. A simple test for spark is to remove each plug and ground it to the head by holding the outside hex section of the plug against the head (keep plug wire attached) and hitting the starter button. You're looking for spark on the plug from the electrode. Do you get spark from both plugs?

Thumper26

 

Actually, I still can't get this being a fuel problem out of my head! What size jets have you got, and are they CLEAN and unobstructed?

Thumper26

 

hi lollypop in SOUTH YORKSHIRE U/K here,just athaught,have you tryed a jump start from a GOOD BATTERY??SOME TIMES THE BATTERY SEEMS GOOD UNTILL YOU PUT AHEAVY LOAD ON IT,hope this helps .tara for now lollypop.

 

Hi Jasper here,
Good sparks,damp plugs - also tried jumping bike from car (Sportster battery going flat) still same symptoms - start - run for a few secounds - then stop,no pops or bangs, as Thumper says seems like a fuel problem, but what ?

 

Well, now it sounds as if maybe you're getting too much fuel. If the plugs were wet. Do you have to crank a little while before it fires up, and quits? Turn the petcock off, and see if it runs a little while longer, before it quits, than with it on. Be sure to let us know what it is, when you figger it out.

 

Jasper here,
Tried fuel of/on etc - the same. Tried swapping coil, new plugs & HT leads, looks like I'm going to have to bite the bullet and visit a dealer soon.
Jasper ;-(