Office of Steam Forum for Model & Toy Steam Gas & Hot Air Engines

Hi Gil,.thx for your very detailed & informative modification descriptions. Although not running near as smooth & slow as yours video attachment does & aside my simple "loosened" governor springs, my Stock M90 starts & runs amazing well ! When I do tear it down & get in there, from your Experience, What is the Max Optimum piston top Cut would you do ? On the cylinder Bore Finish issue, I feel the Optimum Cylinder Bore Finish would be a "delicate" conflicting Quandary, being Very smooth so Not to Abrade the delicate O-ring + having a finely Plateaued Hone or Micro Fine polished Shot-peened (orange peel dimpled) oil Retaining pockets finish to help keep cylinder/O-ring lubed despite O-ring Wiping clean action. Thx again for any info you can spare,.....tom.