I tested 2 of my C-case 40's (lapped iron piston/steel sleeve) this past weekend after replacing the bearings. One engine put out 13500 rpm but the second engine maxed out at 12300 rpm's only. The only thing I can attribute the difference to is piston wear. Both engines have the same exact cylinder measurements but the slower piston is 0.03 mm smaller due to wear. Although I expect loss of compression due to wear, does 0.03 mm make that much difference in performance?
I guess it would be nice to get a new piston and circlips for it. I found circlips at the MECOA site for this engine, but not pistons.
Last edited by hsukaria; 04-15-2019 at 10:36 AM.