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

Bonjour,
I have ordered a pulley and O'rings to Jin, I will be happy to give you a feedback when I receive them.
Besides this, my engine has no compression, Jin suggested me to remove one O'ring, did you apply this suggestion ?

I believe Rog and Gil had this problem and started a thread concerning loss of compression and removal of the lower o ring here :

Problem seemed to be virtually NO compression.  We checked the exhaust and intake valves which seemed to be working fine having removed the head to observe.  Ended up taking head off, cylinder off and found the single green O ring in the groove closest to the top of the piston was barely making contact with the cylinder walls.  I will order some new O rings, but short term we switched the O ring to the other/lower groove...oiled it well and reassembled.   Using a bit of tape to protect the protruding crankshaft on the side without counterweights...a drill clamped on that side running in reverse got it started.  We were both elated after more than 90 minutes of messing with it.  We had even swapped the head from my M90 to see if it made any difference...answer NO.  Problem was definitely the M91's O ring.

Hope this helps! The o rings are 20X1 'll. Glad it is back in one piece and hope you will keep us updated!