Just looked at an engine today identical shape to the 'Redfin' series and reported to be made by CS. Black anodised crankcase. Looked like the .030 cu. in. (0.5cc) size. Made the following observations: -
1. Engine tight to turn over TDC.
2. Coil spring fitted to needle far too long and coil bound preventing needle seating completely. Part off pip left in centre of brass needle at top end.
3. Comp. screw in dull dark yellow colour anodised cylinder jacket far too tight - thread binding. Unable to determine fit of contra piston in bore.
4. Removed cylinder and found two socket cap screw heads fouling cylinder OD with their OD's
5. Conrod fouling base of cylinder bore. Hand Dremel (or Chinese equivalent) grinding marks to base of cylinder attempting to get clearance. Rub marks both sides of conrod.
6. At BDC piston uncovers ALL of two induction holes in cylinder, so on downstroke there will be a puff of exhaust gasses back out the inlet.
7. Transfer ports are two milled grooves in cylinder bore. Should be symmetrical but were not.
8. Gudgeon pin loose in piston, ends not radiused.
9. Steel induction port low temp. soldered to steel cylinder. Should be silver soldered at red heat for the strength required. Corrosion on cylinder base flange due to inadequate post soldering cleaning. No cylinder base to crankcase gasket present.
10. Conrod end bearings can be twisted a lot side to side suggesting conrod bores are 'hour glass' shaped and likely to wear rapidly.
11. Small chip to piston skirt.
12. No evidence of engine having been test run.