Hi Bill and Don, I have exactly the same problem and I would like to have some more info on how to dismount the 21/46 conrod from crankshaft.

As a matter of facts I have used the described procedure too on other engines which do not have a ringed piston, and I suceeded in disassembling a ST 60 and a G21/40 by removing the wrist pin beforehand, using the existing hole in the back of the crankcase (the one with a threaded plug in the G21, simply open to the external on the ST60).

Am a little reluctant to try to remove the liner and try to pry off the conrod in the first instance, because I would really like to avoid the 2 very easy troubles: first of all you will very likely dent the conrod in the process of lifting it with pliers or bolts, and second thing it is very easy to break the ring once you have removed it from the liner with the piston still in place. And when the liner is off and the piston/conrod are still connected to the crankshaft, there is no way of putting it back without removing (read: breaking) the ring.

The presence of the hole suggested me that the way to dismount the engine would be that of lifting the liner slightly in order to expose the wrist pin, align the pin with the hole and then, after heating the entire motor, tap it from the back with a rubber hammer and have the pin simply fall off the piston. At this point the conrod will really come off the crankshaft with no effort at all. As I said it did work twice, but not on the nice 21/46 that I am dealing with now.

On the other side it might well be that the only reason for having the hole in the crankcase back is that of allowing to insert the wrist pin in place during engine assembly, i.e. after having the ring properly seated on the piston and the ringed piston inserted in the liner.

Well, did the suggested removal procedure work without any broken/dented parts ? In this case I might try to apply it as well and risk again to break only the ring.

Thanks in advance

Gianni