I know it leaks gas if you turn it sideways, lol. I think its just a vent, I never bothered figuring it out. I doubt its your problem, make sure you have good gas, fuel pressure, fuel filter, clean carbs, float adjustment, and proper jets. Let us know how it goes.

 

Welcome to the forums man....

Sounds like carb issues. I tiny tiny tiny piece of dirt, and it can clog a jet. Run speaker wire thru the jets when you have them disassembled...Make sure floats are adjusted correctly, and any disassembly of the carbs usually requires resyncing. What kind of gauges did you use for the resync? What are your float measurements at? Did you disassemble the top side of the carbs? How many turns out do you have the af screws set at?

 

Its all clean....did all the regular checks by the book.
Picture this: 5th gear 2000rpm...cruisen fine....foot to the floor and it pulls hard until around 5500rpm and then it kick splutters and breaks up.
My theory is that the main jets are too small as the main jet is responsible for 1/2 to
WOT....Right???
maybe i should just try the next size up on the main jets......what ya think?

 

sounds about right joe555 maybe try up a couple of sizes since they are spendy buggers. Verify with a plug read as well.

 

OK..ive tried 1 size leaner and 2 sizes richer on the main jet with no change.
maybe i need a match......and some fuel!
I need a gas analyser or some way to work out air/fuel ratios without guessing(plug reads are too innacurate)
any ideas anyone?

 

hehehe, forgot you weren't rideing, foot on the floor would give you diferent results

I have had this problem twice on my ride, once because my jets fell out....and then again because of improper fuel delivery. The bike ran fine unless I gunned it and the fuel didnt come fast enough to fill the bowls, so once the bowls drained the engine died (of course by that time I was at speeds where the engine dieing could lead to you dieing so it wasnt fun. But, if you have been through the carbs that many times, maybe you should check elsewhere. How is the spark? coils? pickups? Just throwing ideas out there.