Motorcycle Repair: stripped oil pan threads, time serts, honda rancher

Question
HI,
I have a 2000 honda rancher 2wd four wheeler.
I stripped the threads on my oil pan hole by overtightening the oil plug. The factory oil plug dimenstions are 12mm diam/ 1.5pitch/ 1.5 cm long.  I went to napa and he gave me an oil plug with a higher pitch (1.75mm) but that didn't work.  

Somebody mentioned using an oversize oil plug.  Also I heard a helicoil is a good option?  What is my best option to fix this?  None of the auto parts stores have a helicoil or oversize plug bigger than 12 mm so where would i get one? Do you think a 13 mm or 14 mm would be best since i did go to a higher pitch (1.75mm)I don't know if a 13 mm would hold?  Do you use the same size drill bit as the oil plug you are going to use or a size smaller?  If you suggest a helicoil set then could you give me the dimensions of the helicoil set i need because i looked at some in the autoparts store and the sizes they gave didn't make sense to me or the guy that worked there?  Thanks

Answer
Hi Joe,

That's seven questions if I counted accurately. You're getting your moneys worth. lol

My advice is for you to have a local machince shop repair (restore) the damaged threads. It will cost you less overall. If you have to ask those questions, then you shouldn't be attempting the repair, honestly.

One option a machinist could do is weld (fill) the hole and make a new hole that will use the original drain plug. A machinist has more options than what is available to you. "You can pay them now, or you can pay them later." Later is usually more expensive.

To learn more about Heli-coil repairs, type keyword heli-coil, thread repair, or other related keywords. Time-serts are a better product. Find them online in the same manner.

Respectfully,
Mark Shively