triumph unit clutch

hi have enybody have broblems with triumph clutch" and how much"
i have 63 triumph trophy and i have mysterious problem...
it starts ok if i don´t have to kick several times oter way the clutch does not keep so it seems like the clutch is on base (it usually starts at first) so thats not so disturbing.
but the second broblem is when im riding about 1500-2000 rpm and twist full throttle the clutch does not work bike does not escaled only rpm go higer .i have change my 650 to 750 and front gear wheel 19 to 22 .. well thats all if u have some tips.... i thx.