twowheeldreams
Cam chain change
I didn't replace the camchain, but on the RS engine and of course the XL250/500S and all similar engines to replace the camchain you just need to remove the head cover, lock the tensioner, take out the camshaft and sprocket. At the bottom end clutch cover off, lock the clutch with a screwdriver blade wrapped in rag between the primary gear and the gear on the clutch basket, undo the big nut on the end of the crankshaft. Slide off the advancer and the primary gear, then ease out the oil gallery that goes through the camchain tunnel. All is clear then to drop the old chain through and then tie a wire or something to the new one, so that you can hold it while you drop it through the top of the tunnel, get it around that bottom sprocket and you're away. Assembly being the reverse of disassembly, as the saying goes.
Cam chain change
I didn't replace the camchain, but on the RS engine and of course the XL250/500S and all similar engines to replace the camchain you just need to remove the head cover, lock the tensioner, take out the camshaft and sprocket. At the bottom end clutch cover off, lock the clutch with a screwdriver blade wrapped in rag between the primary gear and the gear on the clutch basket, undo the big nut on the end of the crankshaft. Slide off the advancer and the primary gear, then ease out the oil gallery that goes through the camchain tunnel. All is clear then to drop the old chain through and then tie a wire or something to the new one, so that you can hold it while you drop it through the top of the tunnel, get it around that bottom sprocket and you're away. Assembly being the reverse of disassembly, as the saying goes.