Should have a nice, light pull. [that's what she said]
Check that the clutch push rod (through the centre of the gearbox input shaft) is set up right. There's a rod, a loose ball bearing, and then the rod that's effectively part of the clutch cover. They should all be a loose, sliding fit in the shaft.
The wrong length rod(s), or missing ball-bearing will have the rod pushing on the wrong part of the ramp, and this can cause a very heavy clutch.
Also check that all of the spacers around the clutch basket are right, because they can cause this sort of hassle too.
Does the lever snap back away from the bars if you let go of it suddenly?
Make sure you've got the right lever . Yamaha levers obviously work very well, but some of the older aftermarket levers have whacko leverage ratios.
