I haven't been on for a while, so sorry if you've heard some of this before.
Make sure your clutch lever is the correct one. The original should be a Doherty with 7/8" c to c distance between the pivot bolt and cable end. a lot of replacement levers are 1" to 1-1/8". It does make a difference. A nice Venhill cable makes a difference, too.
Adjusting the cable length, so the actuator cam in the gearbox is positioned right helps, as is adjusting the proper gap on the actuator rod. If all is right, lever should have just a little freeplay, and clutch should be a strong two-finger pull.
Also, I had a bad experience with a Renold chain on my P11Ranger. A plate (not the master link) popped off at 80 MPH and blew a chunk out of my primary. Less than 300 miles on the chain. Luckily, nothing else was damaged and I have a great welder. My P11, G15 and G80 all have D.I.D. chains - cheaper and nearly twice the strength.
If you use a Renold, check EVERY link to make sure the pins are properly punched.