I am getting a bit of clutch slip at full throttle. For example when in 6th at 5000 RPM, if I open up the throttle, it revs up by 500 RPM then jumps 1000RPM and holds at that speed until the car catches up, then it will continue reving normally.

I have fitted new clutch plates 400 miles ago plus a barnet pressure plate and springs. It has always behaved as described, since new and will occur as described at whatever engine speed you happen to be going at.

The clutch action is fine when pulling away or changing gear and is fine at part throttle.

Is this normal for a BEC or is mine misbehaving?

are you using car oil in the engine

No. Bought oil that said Bike Oil on it. Castrol I think. Halfords had that or Halfords Bike Oil.

Certainly sounds like clutch slip. Are you using fully synthetic or part synthetic oil.

Is the oil level right, some bikes can suffer clutch slip on overfilling.

Buy cheaper tyres, less grip!

Mike

Definitely sounds like clutch slip. I do not know what frictions you are using but I have found that Yamaha frictions are much better than Barnett Kevlar ones for example.

To get a bit more pressure on the clutch plate, one trick (told to me by a sidecar racer) is to put a sump washer under the spring to compress it a little more. Since I did this I've not experienced any clutch slip at all including using both synthetic and semi synth oils.

Hope that helps

Paul

Also make sure your clutch cable is disengaging properly with a few mm slack and no sticking points, and also make sure you're not subconciously resting your foot on the clutch (easily done)!

Foot not on clutch pedal at all so it isn't techneque!
I drained my oil and poured back into the original container. 3.1 litres is a bit much. I poured 3.7 litres back in as per Sir Haynes. This has eliminated slip at accelerations starting at 4000 RPM in 6th and reduced the amount of slip when accelerating from 5000 in 6th. Still a bit more improvement needed.

My clutch cable is adjusted so that there is a bit of slack when the clutch pedal is pulled back. The clutch springs pull the pedal back but the clutch release arm spring doesn't. Is this OK?