Running on 3 cylinders

I looked at an 82 KZ1000 LTD tonight. Bike has 29,000 miles. Bike started right up but after running for a couple of minutes #4 header pipe is still cold. The owner tells me the guy he bought it from told him it had a "cracked" sparkplug. He said he never bothered to do anything about it and just rode the bike back and forth to work last summer. The bike has not been ridden this year. If he in fact rode the bike for a summer on only 3 cylinders what damage would you expect to find? Seems the oil should be full of gas yet I couldn't see that in the sight glass. Any ideas? Asking price is $1,000

I would be asking, who in their right mind would be riding a bike back and forth to work with a "cracked" spark plug and not spend the 4 buckazoids to replace it. Before I ever laid down a grand I would pull the plug and take a look and check the compression on at least that cylinder.
Ride safe.

Had you met the guy you wouldn't be asking "Who in their right mind......"
The more I think about it the less I think the guy even rode the thing. I'm curious why that one cylionder won't fire though....