Seized T500?

[morini312]

Roads are icy, so I am trying to work on some of the forgotten projects in the back of the garage. First out is a 1971 Suzuki T500 that only ran on one cylinder when I bought it five years ago.

New points fixed the running issue and it ran fine for five minutes before I turned it off. When trying to restart it the engine would not turn over. This is what I did:
1: Removed the crank drain plugs in case it was flooded.
2: Removed the spark plugs to get compression out of the equation.
3: Put some oil in the cylinders, just in case, and let it stand over night.
4: Put it in fifth gear and tried to move the back wheel.

All to no avail.

My first thought was that it had been standing for too long so that the cylinders had insufficient lubrication (even if I had put extra oil in the petrol) and hoped it was only a minor seizure which could be fixed with honing and new piston rings. Next steps:
5: Pulled the heads to check the liners. Saw that the pistons moved ca 1cm up/down when turning the back wheel (in fifth).
6. Pulled the cylinders which confirmed that the pistons where not seized.
7: Had a long depressing look at the non moving crankshaft and
8: poured myself a double whisky.

This is how far I have gotten in my limited garage time. I know that the crank sealings can dry out when these bikes are not run for long periods, so I have kicked it over regularly. And if that was the problem the crank would not seize, but leak, right?

I am afraid I am facing bearing failure which probably is out of my league, or am I missing a possible easy solution?

Best regards from icy Norway!

[jabcb]

Might be the transmission.

Suzuki modified the crankcase to increase the oil capacity because of problems. You probably have an early motor.

[Vintageman]

I wonder if you disengage the clutch if you can kick it over or with heads off see is you can move pistons up and down more than 1cm with you fingers. Also is the trans in Neutral? I know, hard to change gears is you can wiggle things via rear wheel. If it is in gear on Center stand, what happens if you move rear wheel back and forth by hand, do pistons move at all (1cm as you said)