Temporarily not accelerating

Hello,

I have an 04 VFR800 Vtec (first bike after passing test) and today on a ride I had a couple problems. First one was when on the motorway, I was about to move from inside lane into the overtaking lane to get past a lorry and when I went to apply a bit of throttle the bike didn't gain any speed, the revs went up but speed didn't.
I quickly change down gear and applied throttle and it accelerated.
After overtaking the lorry a service was coming up so pulled in there, when bike was put into neutral the engine cut out completely. Has anyone had anything like this happen before? (I'm not mechanically minded so sorry if it's an obvious thing)
Bike did start up and make it back home without any further issues.
Thanks
Alex

 

What RPM range were you running at the time you wanted to wfo pass the truck?

 

could be signs of a failing clutch if revs go up but speed doesnt

 

I was between 4,500 and 5,000 revs

 

Then I like the slipping clutch suggestion.