the main seal i beleive is what keeps the transmission oil from leaking into the crankcase. it was so much the seal, but the labor costs which was a lot. I consider myself highly skillled when it comes to working on mopeds, but i did not know where to get transmission parts, and i wasnt about to fool around with it, because there were so many little broken parts in it when i took it apart. The kit also managed to completely tear up my clutch pads. I t was proabaly only $50 in parts. The labor costs where close to $225. I probably should have just done it myself. I weled my pipe cause that clamp does jack shit. You can use a special steel epoxy that you can get at any hardware store. It is like a clay that you smoosh up, and when it dries, it is (suppossedly) as hard, and heat resistent as steal. Works great for me so far on other parts of my ped.I dont think the kit could do anything to the studs. The most costly thing that can happen is tearing up the cylinder head, by not breaking in the kit properly, and not using a high quality 2-stroke oil.