I’m pleased to report that a rather pretty box containing a small batch of low-compression Sunbeam pistons arrived this morning. Like the 7.5 :1 CR Model 90 versions produced earlier, these are a lightweight forged item but will give around 6.5 : 1 CR depending on the head and barrel combination in use. Targeted at the Model 9 it is suitable for late 20’s early 30’s 500cc OHV bikes and we have limited availability of both +0.020″ and +0.040″ over-sizes.
Our research showed that the weight of Model 9 pistons varies surprisingly depending on both year and manufacture. After collecting and checking pistons from Marston, Heplex and Specialloid a target weight of 400g was achieved for the new item – including rings, pin and clips.
Once we have given the new arrivals a good look-over we’ll be making contact with those who have already reserved their pistons. So be quick if you don’t want to miss out!