When his motor is already running, the clutch acts normally. The clutch starts to disengage when the lever is pulled in a small amount. It is completely disengaged well before the lever reaches the hand grips. I'm thinking that's not the problem since I had Iso-Grips on my Sportster (much larger diameter) and never had any problems like my son is having.
Here's what I'm thinking. Let's see how well I do explaining my thoughts.
Fact: When the engine is running on my son's bike the clutch acts normally.
Fact: Many Harleys (most?) give a small lurch if you try to start them cold in first gear with just the clutch pulled in.
Assumption: If all else is correct (clutch adjustment, proper oil level, etc) The clutch needs to be spinning at some minimum rpm before it truly disengages when the clutch lever is pulled in. I.E. The clutch does not
completely disengage when the lever is pulled in when the motor is not running. Picture a disk brake. The pads are always in contact with the rotor. It takes some minimal amount of power from the engine to break the contact between the pad and rotor.
It seems to me, if my above assumption is correct, that the springs in the clutch and the condition of the clutch itself will determine what the minimum rpm for complete clutch disengagement will be. His clutch does not want to completely disengage until the motor has reached a higher rpm.
If all that is true, his clutch needs to be replaced. Now I just have to sell that to the dealer.
Any comments? Am I making this more difficult that it needs to be?