I've recently finished swapping the engine on my 1996 900rr and I cannot get the starter to crank, with direct current from the battery. When I take the starter out of the motor however, it cranks without issue. The problem isn't the engine being seized either, because the starter won't crank even when it's not connected to the crankshaft but bolted in the engine.

 

Hey there. A couple of kind of basic questions. Are you sure the battery has enough juice to turn over the engine? Also, if you put the bike in gear, in 2nd or 3rd gear, does the tire turn or is it locked up?

 

Also check the earth connection.