Dennis,
I have been following this thread. It goes along with a lot of others that have tried to address the same issue through the years. I usually don't get involved but I can't help myself this time.
This whole issue of cranks "spinning" is sometimes misunderstood. A crankshaft "spins" anytime the engine runs. The issue of crank phase problems appeared in the early years of Vmax4 racing when engines were operated in an rpm range that created a harmonic vibration. (9200+) This was believed due to the unequal mass of the two crankshaft halves and the final drive design. The difference in weight is due to the respective drive gears. You see this clearly in your photos. Most engines will have a harmonic in some range but they are designed so this effect is not in the normal operating range. Vmax4 750s were designed around a power peak of about 8200-8300 rpms.
The harmonic vibration under load, had the potential to cause the drive gears which are pressed on to the crankshaft, to move a few degrees. This would in effect change ignition timing. They did not "spin" but moved very slightly. I believe very few people with Vmax4s ever really had this happen even though so many who were disappointed with their sled's performance claimed they did. The '92s are believed to be most prone to this issue because Yamaha tightened the press fit specifications on the 93 and 94s.
My point is, you must take the crankshaft to a person qualified to do crank repair. The shop will be able to accurately check the connecting rods for the proper orientation. You can choose to set up the crankshaft so the cylinders fire in pairs 180 degrees apart or individually 90 degrees apart. The 180 degree firing solution was believed to have some canceling effect on the harmonic at the 9200 rpm and higher range it started to develop. We have run motors set up that way for years. I couldn't say whether they or vibrated less or not. This was just the prevailing advice. The 800s don't really require the change since the crank is quite different. Each end of the crank has a gear of the same size. Both halves of the crank mesh with the output shaft gears and there are dampers. We have run them over 10,000 in race form. They will take that in a 90 degree configuration. Some still set them to 180 firing to be safe. Some in prostock setups even eliminated the damping feature because that cushioning would cause a slight timing variance when the motor was loaded hard from the likes of a 6000 rpm clutch engagement on good hard ice.
You didn't mention in the original post how this motor ran before it was disassembled, unless I missed it. The crank gears in the photos were obviously welded. They were either welded in the correct positions on the crank or they were not. You may be right that there are grind marks. It's hard to tell. In order to set up the gears in the right orientation, if they were welded incorrectly, you would have to grind the welds, press the gear off and press it back on in the right place. If the engine was assembled you could get a rough idea by setting the piston in cylinder one at TDC like is mentioned and checking the other pistons' relation to each other. You must at least have dial indicators to do this. Remember, the ignition is triggered by a specific point on the flywheel. The CDI has no idea what position the pistons are in. If they are slightly out of phase the ignition timing will be off.
Please have someone who knows cranks check it out with the proper instruments. It may save you a lot of grief. Sorry if this whole rant offends anyone. It isn't meant to. Just trying to help.
Good luck. Please keep us informed on what you find out.
