Clunk, click...gearbox

[Blimp]

I've been trying to improve the clutch action on my TRX because the gearbox seems excessively clunky (and I've ridden a Sportster). I have a spare clutch from the engine I destroyed after re-shimming the valves a few years ago, and a comparison of both clutches revealed everthing to be normal. There was no warping of the plain plates and the friction plates seemed fine. The springs from both clutches were of the same length, but I decided to buy new ones. I bought the only ones that weren't descibed as heavy duty but they were no different in length, though they were stiffer. Whatever,they made no difference to the gearbox, so the old springs went back in. Someone suggested that the old cable might be compressing and thereby failing to move the actuating arm on the clutch cover fully. Seemed a bit unlikely, but for less than a tenner from M&P delivered it was worth a try...
Unsurprisingly, that didn't work either. The same person also suggested polishing the plain plates with wet & dry, and as many of the plates were discoloured with what I assume was an oily residue, I spent about an hour rubbing away and becoming less convinced by the minute that what I was doing was going to be worth the effort.
However, on trying the bike out there did seem to be an improvement, and I was able to change up the 'box without the usual sickening bang. I suspect that the problem is that the plates don't seperate very much when operating the clutch. I discovered during a previous clutch strip-down that with the oil wiped off the plates and everything re-assembled, the back wheel rotated more easily in first gear and the clutch lever pulled back; but once I started the engine and the oil was able to coat the plates again, the back wheel was harder to rotate. This suggests (to me, at any rate) that the oil is too thick, but I've always used 10W/40...
Blimp