| The key to proper clutch engagement behavior is having the proper clutch plate stack height, that in turn, establishes the point where you get full engagement - and the proper clutch spring preload.
The higher the stack height, the greater the preload on the springs, and consequently the greater the force pushing the plates together when you release the lever. Since you say that the clutch doesn’t sufficiently engage until the lever is fully released, this tells us that the plate stack is a little low, such that there’s insufficient force to prevent plate slippage (and sometimes judder) until you reach full lever extension.
Like Ducati does for the OEM clutches, the manufacturer of the slipper clutch gives specific instructions on the stacking order, plate type, spring plate positions, spring plate orientation (convex side out) and stack height (38mm.) In doing so, they establish the point where the the slipper clutch begins to slip under a reverse torque condition.
You can change this recommended slip point, however, if you raise or lower the stack height. The shorter the clutch pack, the earlier it slips. Race teams do this all the time to suit a rider’s preference.
However in doing so, you’ll also change the behavior of the clutch during it’s initial engagement. On the track, it’s more important to the rider to have the slipper-function engage at the right time, so the behavior at initial launch becomes a secondary consideration.
On the street however, (and in your case,) the recommended pack height is causing objectionable behavior at launch, so the cure is to use a 0.5mm or-so thicker plain plate to change the “friction zone” on the clutch lever. But, then the slipper will need a higher reverse-torque to actuate.
So when you hear “they all do that,” what they’re telling you is that the slipper has been properly set-up for the track according to the manufacturer’s instructions.
The bottom line here is that slipper clutches are primarily track equipment because of this trade-off between road and track behavior. Some manufacturer’s slippers are better behaved than others in this regard.  |