Found the problem for the slipping clutch, it was weak springs, luckaly the local Honda shop sells extra strength clutch springs for a C50 clutch that will also fit the C110 unit. You only need to buy 2 sets as a C50 has only 4 springs.
When compressed to 12mm these gave 9kg's of pressure, compared to the 5kg's I had from the stoch C110 springs.
Also something was found for the gearbox problem, it turns out the old C65 casings have a higher hump inside from the footrest mounting holes. This caused my shifting arm to hit against it and not being able to give the full movement to the shiftdrum.
The piece marked in black marker was cut away and now it shifts like a dream.