I'm an avid motorcyclist and currently have 7 bikes on hand. I've been doing all my own maintenance since 1973 and feel confident with routine matters like shimming a valve train. The '07 650R has me defeated right now. Disassembly was uneventful and measurements indicated several shims were at the low end of clearance. Between swapping shims and spares on hand there was no need to order replacements. Reassembly of cams and tensioner was routine. I began to rotate the engine clockwise and got about 10 cam sprocket teeth before I hit a hard lock. Hmmm, maybe the chain tensioner. Removed chain tensioner and rotated again. If I recall, a cam sprocket(s) jumped a tooth because of slack with no tensioner so the intake cam was loosened, chain adjusted on the sprocket and the intake cam retorqued. Same problem - hard lock rotating forward 10 teeth or so. Next, removed both cams and all buckets. Inspected shims for proper seating in their cavities. Buckets and cams reinstalled. Checked alignment at 2T through view port and doublechecked that cam marks aligned with the deck top and 180 degrees apart. Check. Same problem rotating forward. Rotate engine backwards and eventually hit hard lock roughly 350 degrees backwards. New theory - something has fallen though spark plug hole or something is impeding the lower cam chain gear. Need borescope or maybe take right side cover off. Problem with theory - I did not drop anything into the engine. Also, cylinder #2 is falling as I rotate forward and cylinder 1 is still low so pistons probably not hitting anything. Has to be something impeding the lower gear. Need to figure out how to view that area. Nagging thought that Kawasaki's weird neutral finder might be involved. Anyone have ideas?