rd1970. Wait till you are finished, because you have work to do on that engine plate of yours and the measurements could change. Once you are ready to go,
the correct way to install a new belt is with both clutches OFF of the kart. Loop
the belt over each one, then separating them ( the belt will sink into the driver, as it is open ) slide them onto the crank and jack shafts at the same time. The belts cost enough money, especially the 40series that it is worth the effort to do it the right way. No prying no stretching and no damage.