Vario, yes, clutch pads... unless it is slipping, no.
A couple of questions...
Does it get up to its (current) top speed relatively quickly?
Yes, Its pulls off very cleanly and feels strong
Does it do it in one smooth action or does it feel like it is having a couple of bites at the cherry? i.e. does it smoothly accelerate at the same 'rate' as the revs climb?
As far as I can feel, yes.
Does it hit peak revs quickly? and then the speed increases as the vario catches up?
Not sure on this one, I would suspect it's something I'd notice so i don't suppose so.
Does it feel like it is at peak power or is it struggling?
It feels like it's going well. although as I said it could be rich as it's a little "wooly" but then I'm used to fast revving big bikes. It'll hold the same 27.5 mph at 3/4 throttle., Opening the throttle further on the flat achieves nothing.
On trailing throttle from top speed, are there any vibrations or juddering coming from the transmission or is it all as smooth as silk and revs smoothly reduce in line with road speed?
No vibrations. it just feels like someone is holding it back. It feels like it's "electronically" limited to 27.5mph Like there is something reducing power instead of restricting it (unlikely, I know). . I'm struggling to explain it (I'm a chemical engineer and ex bike racer so I know my two and four stroke engines and general mechanical principles.)
The reason 27.5 is strange is that going up hill, down hill into or with the wind it still does 27.5 mph. Surely if it were a power issue it would drop into the wind and up hill. And I'd expect it to run away down hill but it doesn't it's like it's trailing the brakes without you doing so.
Can you weigh the weights? Or are they marked with a weight?
I've not had them out but could take it apart at the weekend.
And 60mph is fairly optimistic of your mechanic... it
is possible, but it will take a bit of work... 45+ is eminently achievable, though. Are you sure it is a 1991? How many miles... it may just be very tired...
It is a 1991 and has aledgedly done 4000 miles although this is probably a "little" off. It feels fresh and it feels like there's a lot of go left in it yet. The plug will be out at the weekend so i can see what's going on with the mixture.