FWIW...The 090 cylinders were used by Dale Herbrandson, builder of the 280 and 289 twin drone engines we use in our race planes.The bottom of the cylinders would break off after about 100 hours on the dyno....About 26 hp in the stock version..The saws had a governor that restricted the rpm to about 7000, we turn the twin 9000+....New cylinders are getting hard to come by, about $350 with a piston...