Here are some documents and images to provide you with more technical information.

Ossa Service Bulletins

Clearance Chart

Gear Transmission Information

Ignition Timing Settings

Trasmission / Fork Oil Capacities

Ossa Bolt Size

OSSA Port maps/ Schematics

(Click image to enlarge)	Case Screw Lengths and Position on Large Clutch Covers
(Click image to enlarge)	Case Screw Lengths and Position on Large Mag Covers
(Click image to enlarge)	Case Screw Lengths and Position on Small Clutch Covers
(Click image to enlarge)	Case Screw Lengths and Position on Small Mag Covers
(Click image to enlarge)	How to Measure a Case or Cover Screw