Yeah what Jared said because basically you got one bearing with a thin snap ring holding your crankshaft that’s only made for Side thrust loads on only a 2HP engine if that so it can flex Back-and-forth,
When you push the starter clutch the snap rings can flex and crank can move to the mag side, when you accelerate and decelerate it can just go back-and-forth back-and-forth In some cases wearing out the aluminum cases in the bearing areas.
Some people send their cases out to a machine shop to get another snap ring groove machined into it for to use 2 snap ring bearings for more sideways thrust strength and some people like me glue the crank bearings to the case though that’s pretty much only a one shot deal,
Straight cut eliminate side thrust problems and allow all the power to go directly though they are noisy and are not as strong as helical cut gears