What about welding the crank.....in the zenoah 260......

Crank welding was tried a few years ago with only limited success.

The crank pin is Case hardened high carbon steel, the crank half's mild steel forgings.
When TIG welded the two parts get there natural molecular structure altered causing them to become unevenly stressed at the area around the weld site.
While the actual weld will help to keep the crank in alignment, it actually weakens the integrity of the parts.

High grade air conditioning use type Silver Solder >>>>>>>>>>>>>>did it on some motorcycle cranks , don't remember which make,.. gotta use lots of heat and be quick before you really heat the pin -chill the rod end and pin with CO2 fire extinguisher before you start -- tried brass took too much heat softened pin I havn't tried this on a Zenoah crank , It might be a little small to work but >>>>>>>>>Wot The Hell