The cork washers are a pain, and have to be grind to correkt thickness. So I convert to use a spring to held the breather in place. Running in seval engine since thousands of miles with no problems.
cheers Klaus
Klaus is correct of course, but amusing people still using cork washers, along with other Colonial pursuits. However,,,,
If you wish to truly master proper end float, shimming and use of proper materials than nothing can compare to shop notes from the Hurley Pugh collective, especially those shims & washers!.....to wit:
" With the crankshaft in the correct position, remove the six bolts that secure the magneto to the top side of the crankcases. You will notice that all of the bolts are different lengths - it is crucial that these are replaced in the correct holes otherwise you will lock the gearbox solid. Underneath the magneto you will almost certainly find one or more thin shims, fitted by previous owners. Hurley-Pugh itself did not actually shim the magnetos when the engines were originally manufactured. Instead, Bill "Masher" Stubbings precisely adjusted the magneto's mounting points by the careful application of a large hammer. If you look closely, you'll probably still be able to see the dents in the top of the crankcase where "Masher" skilfully wielded his scarred hammer. As Hurley-Pugh did not shim the magneto it didn't produce any shims; again, the Hurley-Pugh Enthusiasts Club can oblige with a set of paper shims for a reasonable 280 pounds complete.
Inspection
With the magneto removed, examine the teeth on both the gearwheel and the conrod for signs of distress. Any evidence of chipping, bending, burring or missing teeth will require replacement of both the magneto gear and the conrod, as well as a complete engine strip to remove the debris.
The leather friction washer can be found between the gearwheel and the magneto. To inspect this, use a blowtorch to heat the gearwheel to cherry red and use a 400lb press to ease it off the shaft. The heating process usually destroys the leather washer so it will need to be replaced regardless. Note that the washer is made from treated rabbit skin; some unscrupulous suppliers are selling washers made from inferior cow leather but these parts will not impart the correct amount of friction so should be avoided. The easiest way to test if a washer is from cow or rabbit leather is to send it off for DNA testing.
Adjustment of Friction Washer
The precise amount of friction that the washer imparts on the magneto shaft is crucial to ensuring correct alignment of the gear teeth in operation. Adjustment is obtained by moving the gearwheel slightly in or out on the shaft. The friction is at the correct setting if, with the magneto at operating temperature (60 degrees centigrade for European models, 70 degrees for Empire models - pad the magneto in clean towels and put it in the family tumble dryer until it is at the correct temperature) you should be able to ease the ungummed edge of a Rizla Green King Size cigarette paper - note, NOT Rizla Red - between the magneto body and the washer. If there is insufficient clearance, allow the magneto to cool then prise the gearwheel away from the magneto with a large tyre iron. If there is excessive clearance, tap the gear with a hammer.