the only Zenoah engine that could be lightened was the first model that was produced, big flywheel and big fins. remember this engine was designed by Komatsu for the use of cutting grass then all of a sudden someone cottoned onto the size of the internal ports etc and started to mod these for R/C use, actually BH. Hanson was one of the first to do this with R/C Power boats. i must say they are a great engine and do have heaps of power and even alot more with mods done to suit needs, available mods include H/P head kits, Full Circle Cranks, Bigger Bore Walbro Carbs, etc. the Zenoah Engine is made in Japan which as we know is good stuff compared to some other country manufacturers and spare parts are quite cheap if you go to Komatsu spares.