I have an old 3.5hp Briggs vert. shaft motor mounted on a frame for my train that I can ride in my yard. I is and has been very hard to start for a long long time. This is the second motor that I've had on it for this reason. I have pulled so hard and long on the starter rope that blisters have fromed between my fingers. The question that has come up is since this thing was on a mower and had a blade and now that I just have a pulley on it, do I need to change the flywheel from an old Horz. shaft motor? We tried to put a large block of steel on the shaft, but I only have 4' between the frames. All these old motors came off mowers that had run their course. Any thoughts to my problem?