Yamaha xs650 mikuni setup advice

can any one please assist on carburation advice on a single carb conversion using a round bodied VM36mm Mikuni. My current set up is as follows:
slide 2.5
needle 6FJ6
needle jet n8
needle postion bottom
Mainjet 220
Pilot jet 40

Symptons are as follows, engine dies when giving a quick throttle action. Raising the idle speed helps but not totally. Pilot jet has been changed from 25 to 40 which has helped.

Can any one help?

The bottom line is that a Mikuni carb does not seem to work very well with a single carb conversion. The best thing to do is obtain a Dellorto 38mm pumper - this works a treat. They are often for sale on e-bay.You can then contact Dellorto's UK importer in Reading who can supply the exact jetting for your conversion-they are knowledgable and helpful about this. Another place for good advice is Mark Goodall at Kamar Motorsport on 01420 23325