I did this on the transmission plug and transfer case plug on my old 800. Get a tap, drill bit and appropriate plug to fit. Just go the next size up. The oil in the pan will help lube your tap, go in and out every thread, this should take you about an hr and a half to make your threads. Use lots of q tips to pull out the shavings every time you pull the tap out. Use teflon tape on your new plug, for good measure.
I do not recommend using a heli coil, my experience with them is that if you dont fit it just right, the coil will stretch out.
You can use a rubber grommet stop but if anyrhing catches the locking clip, the plug could come out while your riding and lose oil and your engine.
Best bet. Tap it
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