The clutch spring bolts must be tight or they will back out and cut a 6" diameter hole in the clutch cover.
 

A clutch that does not fully release (still transmits a little power when the clutch lever is pulled in) is usually due to one or a combination of the following:

1.  Warped clutch plates, steel or fiber.

2.  The inner basket does not rotate freely after the clutch shaft nut is tightened and before the clutch plates are installed.  (bearing sleeve is too short or the heavy washers on each side are worn)

3.  The clutch plates are not moving far enough from each other when the clutch is fully released.  This is usually caused by using any of the easy pull mechanisms or some of the aftermarket clutch levers that do not have the same geometry as the OEM lever. 

4.  Putting a short arm on the clutch actuator.

5. Missing one clutch spring or using one wrong spring on one post.

6.  Using a clutch cable that does not move freely.

7.  Using transmission oil that is too thick.