Thanks to Butch Lottman for sending in this email with photos about rebuilding his friend’s 503 top end. (Click photos to view them full-size.)
Rebuilding a friend’s 503 top end. Boring cylinders, larger pistons, rings, wrist pins, and bearings. This is what happens when you don’t adhere to Rotax’s maintenance schedule. Pistons had over .040†carbon buildup on them. The piston on the PTO end #1 had the crap beat out of it as well as the head. Areas of the top ring land were broke off. Deep scratches in the shirt and cylinder wall. This is about a $1500.00 repair. My labor is free to friends. Please do your inspections per Rotax.
11/12 – Additional Photos
Thanks to Butch for sending in a few additional photos. These photos have been added below and are of the wrist pin extractor he fabricated, photos of it in use, as well as the pistons removed. Photos are also of a device that he made to capture the cage less needle bearings that are used on the connecting rods.
