Look real carefully at the frame/subframe, look at the swingarm - is it bent/twisted/warped? If it was replaced, why? Think about what a bike might look like after a wreck on each side and then observe where the plastic meets with the holes. Does it look right? Ask up front, why is the title rebuilt? Tell me about the history of the bike or the previous owner. Was it ragged? Check for any signs of a wreck in other words. Scrapes on metal anywhere, scrapes behind the dash (bike flips, windscreen comes off, scrapes dash. Check for missing bolts anywhere.
It might actually help for you to download a blue print of what a ZX-14 looks like from any of the various websites out there that can provide this to you free of charge. Then see if those bolts are missing anywhere. Not all, obviously, but key bolts, like, for the engine and what not. Depending on which ones might be missing, it still might not be cause for concern as they may have just forgotten to put them back after doing stuff like replacing the stock fender or tinkering with the fuse box. Check the wear on the brake pads, front and rear. Do they look pretty evenly worn? If you can, put something in the front of the bike and crank it, turn the lights on regular and bright and make sure they're aiming properly. Is one looking off to the side? Might have been impacted during a wreck, in other words.
Check the wear on the tires - any weird wear patterns? Turn the bike all the way to the right and left and make sure they line up where they're supposed to. Might help you to bring photos of a pristine '14 for reference purposes. Get down on one knee and look at the bike from the rear and from the front. Does it all line up properly? Ask what kind of oil was used in the last change and inspect the quality of the oil in the side indicator with the bike upright. I know this is going to sound strange, but smell the oil. You're looking for any abnormal burnt smell.
Take a look at the bolt that's directly underneath the bike for the oil drip. Does it look like it's been scraped as if from asphalt/concrete? You don't need to take it off for this, FYI, and you don't want to as oil will definitely follow! 
Inspect the chain and sprocket. For the sprocket, you're looking for any teeth that might be worn abnormally and for the chain, you want to check general condition. You can tell a lot about a bike in the chain alone. While you're down there, check the slack. When you pull up on it, you're looking at about an inch and a half and not much more.
When you're done with this part, ask to take it around the block and test the brakes. For the front, do they start to grab where they're supposed to? Check the reservoirs at the dash. Are they at proper level? Does the rear brake feel mushy or is it sound? You're listening for any metal-to-metal during all of the brake-checking, of course. Go through all the gears. Listen for any excess chatter or metal grating sounds.
This should get you in the right direction. I'm sure there are things I'm missing, but this is just off the top of my head. Good luck and if the whole thing doesn't feel right, don't be afraid to walk away.
* Last updated by: loadedmind on 9/20/2010 @ 1:20 PM *
http://www.youtube.com/watch?v=wmufqEW7Gtw&feature=player_embedded