Treewk, I also have a Tecumseh TC200 21220 B 6092G that came with a Viper TC3 friction kit I bought several months ago. I never even took a look at the clutch size but from the mounting bolt spacing, it also appears to be a 54MM clutch!
motorbikemike45 & augidog, there is a metal shroud that is covering up the clutch drum assembly and is roughly about 65MM. I will not be able to remove it until Sunday (if I dare). Honestly, the whole unit has been running well and i'm just a little afraid of messing around with the current setup. You know the old saying... why mess with it when it ain't broken. you would think another member would know the clutch type/size of the GZ25N since it's been around for awhile!! I guess these engines really never break down for anyone to even want to open it up and see. my wife has told me to get rid of some of my other motorize bikes so i plan on keeping my Staton with the Mitsubishi TLE43 and this GEBE with the GZ25N. With the extra cash i plan on buying a spare GZ25N engine just in case i ever go on that cross state bike ride i've always wanted to do.