A reliability and safety concern when using CRF50-type pit bike engines on a racing kart is drive sprocket alignment. This first mockup is the extension shaft, which will be supported by a bracket and a bearing. Products already on the market extend the shaft for pit bikes, but they are not long enough, and a multiple pieces bolted together style of bracket is unlikely to stand up to shifter kart abuse. Because the engine drive sprocket sits inward of the ignition, it does not line up with the keyed and reinforced part of the rear axle, so a new keyway has to be drilled, which is not for everyone. In some cases the third bearing carrier also has to come off the chassis. After that change the axle is driven through an unreinforced area that is now further weakened, with a real risk of shearing the axle. That risk is very real with higher powered engines such as the Daytona Anima, ZS190, ZS212, and the Yx (KLX) based engines shown here.