There are two small bolts and a big nut, 17 mm I believe, with a slotted screw in the middle of it holding the sprocket to the output shaft. In order to loosen it (the big nut), you must first pry back the little tabs that surround the flats on this nut. The "tabs" are part of a tabbed washer that sits behind the nut. Once the tabs are pryed
away from the nut, loosen the nut, with the transmission in gear (to hold the shaft stationary). The nut is right handed thread. The slotted screw is the adjuster for the automatic chain oiler (I THINK the K3 has one), and will come out with the nut. Then, Remove the two small 10 mm bolts, then turn the sprocket slightly either way to disengage it, and pull it straight off the shaft. If memory serves me, this is the proceedure. Of course you must first remove the engine sprocket cover to gain access to all this. Hope this helps and I haven't left anything out
