If my memory serves me, even the pre-production P11A provided by the factory for the press to test was plagued by the clutch to slip ..... I believe this was a common problem with all Atlas-powered hybrids. The clutch torque capacity is marginal for this engine. Have you tried Surflex or Barnett plates? Barnett claims their friction plates are better with ATF than others. Wetting them before fitting is recommended. You don't say who was the supplier of parts was. Please beware of buying cheap parts not up to spec.
Correct friction plates for the P11 have p/n 043192.
As for the dragging problem, you need to check your plain plates for flatness. I trust you have fitted dimpled plates with tangs not dragging in the clutch housing?
I don't understand why there should be any significant cable slack once the clutch is hot. I mean, how hot can it become? Maybe you have an abnormal amount of heat generated due to ongoing clutch slip? If so, your clutch springs (
040358) may be the culprit. Did you replace those with OEM quality replacements? Have you verified that your pressure plate (
043362) lifts squarely?
Is your clutch operating lever (inside the cover), p/n 040029 the correct one? The one used on the Commando is different and gives an unfavourable lifting ramp.
Did you fit a 1/4" bearing ball and a two piece clutch pushrod? It's an old trick to improve clutch action.
http://forum.ozvmx.com/index.php?topic=33926.0
Fitting a clutch mainshaft seal (Dynodave's invention) to prevent ingress of gearbox oil contaminating your clutch friction plates is a very good improvement. Look up "Atlantic Green Norton" in your browser if you want to order one.
Pls. read this thread as the poster seems to suffer similar problems to yours:
http://www.jampot.com/forum/viewtopic.php?f=20&t=5522&sid=7f6f9efa20aa0da019f4e5d1de2e203b&start=10
Beware of the danger of mixing new and old parts of unknown origin. For instance, the pressure plate changed over the years.
If all this doesn't help, you should try to reduce the gearing by fitting a larger crankshaft sprocket - go from 21 teeth upwards. The taller the gearing (42/19, 42/17, etc.) the more load on the clutch.
-Knut