My option is to fix thread by using Helicoil spring thread inserts. There is so many variations like Recoil, Baercoil and many others. Here is what you need:
-Helicoil or other spring thread insert (STI) kit. You need the kit, because there is non-standard STI metric tap and drill bit.
Here is mine, since the heat switch is M8x1,25 metric coarse thread. Bought it for approximately 10 dollars.
-Hand drill
-Some screwdrivers, wrenches, pliers
-Rags and bottle to drain the carburetor
Here we go:
1. Safety is a first priority, so disconnect the negative terminal from the battery.
2. Remove the gas tank, there is plenty infomation on how to do it.
3. In my case i can separate the float cover without carburetor assy removal, so i just put plenty of rags underneath the fourth carburetor and drained the float camera into the some kind of bottle.
4. Remove the float cover, disconnecting the oil hoses (if equipped) and thermo switch terminals.
5. Flush down the cover of any remaining petrol and get ready to rumble!
6. Unscrew the thermo switch and drill a hole through the faulty thread using the drill bit that came with the STI kit, it is 8.3 millimeter in diameter for the aluminium.
7. Using the provided STI tap, make new thread in cover body
8. Put your appropriate lenght M8 STI in special tool provided
9. Drive it in so there is no thread pointing out the hole
10. And you pretty much done, just snap of the Helicoil STI tang with tool provided, or using the pliers. No need to use sealant, i suppose.
11. Assemble in backwards. Dont forget the copper washer for the thermoswitch/
Now you have, as manufacturer claims, a stronger and better thread that it was before, but no need to rush down and use too much force, the float cover is still aluminium and switch still brass, so you have plenty of things to break.