I don`t have access to accurate measuring gear for the clutch pack measurement. I have measured the depth though from the clutch hub to the front of the "fingers" and the dimension is way below the recommended figure of 17mm. Mine is only 14mm!

I believe that the difference can be brought down by the use of thinner steel clutch plates/shims but how do you know what size to get? I don't see a note of the size of the existing ones anywhere. Is there a "rule of thumb" (e.g. a 0.1 mm thinner plate will give 2mm to the overall dimension therefore I would need to replace 2 plates).

If you don't know the original size then how do you know what size to get the new ones (other than buying a set of the thinnest ones and try replacing one at a time).

I had a problem recently with a slipping clutch on an '04 250. When I dismantled the clutch the friction plates were pretty worn so I got three new ones. After fitting these with the original steel plates the best measurement I could get was about 15mm from hub to fingers. I got some different thickness steel plates and by juggling various combinations ended up with 17mm. It meant having to refit the best of the old friction plates but the clutch works fine, no slip-no drag.

If in doubt speak to Kev at John Shirts.