’81 SRX’s are notorious for burning down because of their piston/porting design. The ports are so large in volume and the piston skirts are so small that the pistons can rock in the cylinder at TDC. I had one of these sleds and ended up having to have Forest Lake Motorsports put new sleeves in the jugs that had bridges in the exhaust ports. After that we put so many miles on the sled that it damn near fell apart without burning down again that is until dad got the oil breather tube iced up and starved the engine for oil.