What to check when buying a bike

[Jimbob]

A friend of mine is looking at buying a 2nd hand bike soon and I'm just wondering what things you should check to try and make sure it's in good order etc? Thanks

[jestercinti]

That's an easy one:

-- Overall physical condition.  This will give you a starting point the bike's condition.  Poor physical appearance may directly correlate to the engine condition.
-- Engine noises/sounds/smoke.  Does it rattle, tick, knock, smoke?
-- Start the engine COLD.  Put your hand on the exhaust pipe to make sure the guy/gal didn't warm it up before you got there.
-- Age and Mileage.  Too high, and there could be issues.  Too old, and expect repairs.
-- Ownership records.  Title, maintenance history, paperwork...all important.
-- Fluid color/condition.  Recent oil change might indicate that they are hiding something (not always), but something to keep in mind.