Did you do the 18K service at 36,000? If not, change all plugs. Also do the rest of the service and give the rad a good thorough clean inside and out. Look for the fouled spark plug. If you have a bad coil, the cylinder with the fouled plug is the one with the bad coil. If you did the 18,000 mile service, keet riding until your engine light goes on. Coils can work intermittently. It is rare that during a failure, you won’t get an engine light or a code thrown. If your situation is intermittent, at one fail or another, you will get the light and the code maybe not every time but sometimes. If you never get either, the vast likelihood is that you have a problem other than a bad coil-maybe a fouled injector or bad gas. Try injector cleaner and octane boost before you rip your bike apart for nothing.