How-to make a Tecumseh adjustable main jet
 

Here's a simple mod that will make the stock or modded 6.5 hp Powersports Tec motor easier to get dialed in fuel wise.
There doesn't seem to be an ample, if any at all, supply of main jets for the Tec engines, most of the older ones use an adjustable main jet (carb bowl nut).
Using Oregon carb rebuild kit UPC# 0 32488 49840 6 I was able to make one that works.
The jet in the kit has the same 2 supply holes and the smaller angled hole one finds in the stock 166 jet, all in the same locations as the 166. With that verified, I ground down the top set of threads on the new jet on my belt sander then milled it down to the same height as the 166 in the same manner.
I followed that with a fine file to get it as close as possible to the stock diameter.
A light beveling of the inside diameter was accomplished by gently twisting a 3/16th drill bit in the top. Blew it all out with compressed air and assembled the needle with the spring, brass washer and o-ring supplied in the kit.
My spark plug is now showing a much better burn coloration on the ceramic.
Pics are comparisons of before and after.:biggthumpup:

This is the GY6 section

Sorry, my bad; initially i had a hard time figuring out where the correct small engine tech area is, just realized it after you posted. feel free to move to correct location mods.