Does anyone know anything about the various VHM head inserts that are out there? It seems like every RS125 motor (w/ VHM head) I've peeked inside has a different insert installed. I've seen numbers like #50-68, 50-69, 50-3, 50-136, etc etc.) I've been in touch with VHM and they've been happy to tell me what these numbers translate to spec-wise, but aren't able to offer much insight beyond that. My very rudimentary understanding is that VHM inserts ending with a number are 'custom made' for various retailers and teams while inserts ending with a letter are 'off the shelf' production ones (thus can be found in VHM's product listings). Also, it seems 10.Xcc inserts are for leaded fuel while 11.Xcc inserts are for unleaded fuel. So I wonder why some VHM inserts will list the exact same specs except for squish? In other words, two different inserts will list 10.2cc volume, +2mm piston height, yet one will list .60mm squish and the other .65mm squish. I thought squish was set by base gasket thickness? Is VHM saying that these particular inserts should be set to these squish specs to work as designed? What happens if you are in between base gasket sizes? Err on the side of larger squish? Just trying to further my understanding of VHM head inserts. Also, what do people like to run?
RScycles site has info. https://www.rscycles.com/category_s/130.htm VHM site has info https://www.vhm.nl/en/partsfinder/honda/rs125-nx4/vhm-head-inserts/groups/ma+mo+a+view
