LRP .30 Spec II; LRP32810_engine.pdf
LRP .32 Spec IV: Nitro Motor ZR.32 Spec.4 Pullstart | Product | LRP Home
Dynamite .31 Gas: https://www.horizonhobby.com/31-gas-...xxl-2-dyne0505

LRP .30 - 19.2mm bore/17mm stroke
.32 - 19.8mm bore/17mm stroke
.31Gas - 19.2mm bore/17.6mm stroke

Unless you have an engine with a different piston/liner than it’s supposed to have, you don’t go by what is stamped on the piston. You work with measurements. The published information on these three engines (that are ALL made by GoldenLion/SH Engines) is posted above. Not arguing, just stating the facts. Measure your piston and get a button to fit that bore.