While you are doing that Rob, you might be able to clear up some flywheel-related questions.
1. There must be a reason for the GXV140 and GXV160 requiring spacers under the ignition module, where the GXV120 doesn't. Are the rims of the GXV140 & GXV160 flywheels deeper than the GXV120 flywheel? That might explain some problems a member had in another thread, with flywheels.
2. The GXV120 has a cast iron flywheel, where the GXV140 has an aluminium one. Is the GXV160 flywheel cast iron, or aluminium? If aluminium, is it the same as the GXV140 one? Are the magnets the same on all the flywheels - same number, in the same place?
3. Are the chonda flywheels the same as the Honda ones, for all three models? I'm not suggesting you pull the flywheels from these engines to find out, but hopefully you will be able to tell without doing that.
