I don't know if this will work with the 1800 but I've used pvc to drive seals on other bike forks, equipment cylinders, and gear shafts. Schedule 40 PVC softens surprisingly easy with just a little heat, if split it conforms to a new diameter larger or smaller and stays that way when cool. Take a piece of pvc and split it or cut a strip out so it can be reduced, I run it down my table saw. Warm it with a heat gun, I think a hair dryer would be hot enough. Press it over the end of the shaft to make it bigger or slide it down over and squeeze it shut with your hand to make it smaller. Cools in a few seconds and stays that way forever, a perfect fit. Make it long enough and tap it with a mallet.
05 1300R -sadly sold 04 BMW K1200LT - Luxury Tourer, smooth efficient quiet power,sporty mile eater 05 BMW F650GS - rugged and elegant adventure tourer, does it all well, high speedcruising to rough dirt roads
IBA: SS1000,SS2000, SS3000, BBG1500, 50CC, UCC, LGL1000, 4 Corners