Before you even think about working on it, you’ll have to go out and buy, borrow, or steal some Metric tools.

A 1/4" drive socket set with both Metric and SAE sockets will become your best friend, especially around smaller fasteners as found on carb and ignition components. A 3/8 drive socket set and a full set of spanners or box end wrenches should handle the rest. Deep sockets can be purchased as needed. At least your Phillips and slotted impact driver bits can still be used on the Yam.