loss of power at 6000 and then 10000 rpm

[multiplicity]

Basically, in 1st gear when I hit roughly 6000 rpm the [size=100%][/size][size=inherit]engine[/size][size=100%][/size]/exhaust starts making a 'duel noise'  - the engine sounds like it's starting to strain. Then at 10000 rpm the bike loses [size=100%][/color][/size][size=inherit]power[/size][size=100%][/size] and actually starts to slow down!! It feels like a massive dip in power. Anyone any ideas please?
 
 Ta

[Fazerider]

Assuming this is the same in all gears, I'd check the air filter and that nothing is obstructing the airbox. After that, sparks.
If it really only does this in first gear... erm.. does the drive sprocket still have teeth on it?

[Grahamm]

The FZ6 does have a notorious hole in its power curve, around 5-6000 rpm. AIUI that's where emissions testing is done, so Yamaha detuned it a bit around there.

You can see details here

[fazerboy1969]

Airbox appateur blocked..happend me..

[Gnasher]

Airbox appateur blocked..happend me..

 Good place to start, failing that it could be a sensor/fuelling problem run a diagnostic check.  .