Let's talk about the 4 basic types of Briggs engines that we deal with in kart racing.
 The most sought after would be the double bearing cool bore, an aluminum bore motor with a roller bearing on both sides of the crankshaft. Hard to find.
 Next is the double bearing IC (steel bore). Both of these are very popular and both have won a lot of races.
 The other group includes the single bearing cool bore and the single bearing IC. These have a roller bearing on the power takeoff side and have either a plain bearing or a DU bushing (teflon impregnated bronze) on the flywheel side.
 Any of these 4 types of motors can be fast and win, if properly blueprinted and maintained.
 Now, let's build a competitive motor piece by piece.