So you replaced the clutch plates and not it won't start? Did you mess with the sensors in the process? If so, make sure you have all the wire connectors tight. If you're talking about the sensors that signal the igniter when to fire the plugs, you'll likely have two of them and if so, then that isn't the problem. Two don't fail at the same time unless you busted them in the process. If you didn't remove them during disassembly, also forget them being the problem. A shop manual (which I don't have for your bike) will give you the proper resistance and continuity values.
________
Cheap Tractors