Did you try the '88-'94 Honda factory service manual that you can download from the manuals/schematics section of the forums? I think it has a few tests for the regulator/rectifier. I always just start the engine and measure the voltage at the battery. If it's charging properly, the voltage should increase as you rev the engine. It should show about 13-15 volts.
Most 4-wheeler problems are caused by a loose nut connecting the handlebars and the seat!!
You only need two tools in life -- WD-40 and duct tape. If it doesn't move and should, use the WD-40. If it shouldn't move and does, use the duct tape.