Engine Trouble Crankshaft locks up/ wont spin either way

Not sure what is causing this. I have tried derailing the chain from the rear sprocket, but the front sprocket does not want to turn. Clutch on or off it wont budge. What could cause this? Nothing is blocking the chain.

 

open the clutch cover & look for something stuck in the gears

also, you can take off the flower nut & pressure plate and see if the crank turns (without spark plug), and if the output shaft turns

 

The chain was doubled over if that makes sense, it had a 'broken back'... thanks

 

I know exactly what you mean. That's a symptom of your chain being too loose.

 

Why on earth do people persist with using a single speed drive method; with such limited operational capability. If a car only had a single gear in the gearbox, people would be up in arms.

 

That doesn't have anything to do with this. I understand your desire to be evangelical about something you feel is a big improvement but save it for topics where it's more relevant.

 

Would you like me to delete my post, if it causes any consternation?