I need a piston ring, and bearings for my supertigre G 90. At tower the ring runs $10 and the bearings are $12 and $15 each. Are there any other bearings out there that will work? Perhaps better quality? GMS and "tower engines" also sell replacement parts for their 75 which are significantly cheaper. Is there really that much of a difference in these parts? Supertigre uses the same bearings for their 61-90 and I assume a tower or GMS 75 bearing would also fit. I bet most of these companies order bearings from the same bulk distributor. Any thoughts?