I've been recently working on a Cr125 engine and the water pump shaft was in bad shape and didn't seal properly. The gear is a press fit and can be easily removed from the shaft. Two different ways come in mind for repairing the shaft. One is to turn down the diameter of the shaft and press fit or loctite a sleeve with the correct dimensions. Instead, I just tig welded the shaft with stainless wire (ER308 type, don't ask if it's the correct rod, it's the only one I had laying around). Then comes the lathe, turning the shaft diameter to it's correct dimensions. And here is the end result, ready to be installed on the clutch cover and hopefully serve for a few more years. Here are the dimensions, please note that this is for the CR125R 1998 model ONLY!