piaggio nrg rev problem

hi there
iv got a bit of a problem , right i hit top speed and i drop the revs but then i try to open right up it will not let me rev up but after 5secs i can then open it up and revs are back
sound like there no spark as such
it only does it at top speed
help ! :beg:
thx

 

is the bike standard or has it had any bits and bobs done to it ???

 

yer its had a TT exhaust
but im changing it tomorrow to a dolpper s3r and rollers
thx

 

in that case you want to try dropping your roller weight and see if that improves things...

also could be your idle mixture not set up properly...