5/8 shaft with 4g problems

OK. I have been messing with this hs142f 5/8 shaft kit for almost two weeks now. With the 4g setup it was clattering and jerking when engaging. So yesterday I put in a new clutch, seemed to help a little. But really, do these 5/8 shaft kits really rattle, clang and jerk that much when idling and engaging?
I have just put my 3rd tapered shaft kit with 4g trans together today. Went out riding and I have to say the tapered shaft kits are much better. They are quieter at idle and the clutch engages smoothly. How have you guys fixed this with the 5/8 shaft kit? Or have you not compared it to anything else to know the difference.

I just got rid of that bike. Guy wanted it and was ok with the noise and engagement. Let him try the other one to see the difference, but it didn't bother him. Guess some people don't mind. Anyhow, no more 5/8 shaft engines for me with the 4g box. Maybe when I step up to the Qmatic drives then I will consider the 5/8 shaft engines. Thanks for the reply.

I had cut a new flywheel key already to get the best fit possible. I guess there are fixes for certain things, but I would rather not have to go thru all the hassle just to be able to make the 5/8 shaft kit right. I found it simpler to just get the tapered shaft kits, pretty much bolt and go. Unless someone can tell me the benefit of the 5/8 shaft vs tapered shaft other than gearbox upgrades, which the Qmatic already offers an adapter for the tapered shaft, I will just stick with the tapered shaft. My reasons are below.

5/8 shaft with 4g:
1)clangs and rattles at idle
2)tries to engage at idle when clutch gets hot
3)engagement rpm too low, jerks motor real bad till you get some speed going, even with pedal assist (good luck adding washers to raise rpm engagement)
4)Have to remove gearbox to change the oil
5)Need to replace the key immediately

Tapered shaft with 4g:
Opposite of the above!