Raptor 660 and 700
 

I have the option to either buy a raptor 660 or a 2006 raptor 700. Is there anything i need to look at on these. What kind of monthly or yearly maintenance will i need to do to it to keep it running well. Thanks

Get the 700. I have owned both and the 700 is without a doubt a much better machine. The 700 looks better, is more powerful, smoother, handles MUCH better, and it's fuel injected.

Monthly maintenance would depend on how you ride and your riding terrain, but you can start by cleaning the air filter, greasing the joints, keeping the oil changed(not monthly), keep the chain tight and lubed, check the brakes and change as needed, keep the tire air pressure correct, check the anti-freeze, check all of the bearings ball joints and bushings, check over most bolts for loosening, and a visual inspection after each ride will help. The Raptor is a solid machine so you shouldn't have too much trouble with it.

^^^ Couldn't agree more. These are good machines that will last a long time if properly taken care of..

Do I need to worry about the crank shaft. I heard they tend to break.

I haven't heard that or seen that happen on the Raptors.

I had a 660 with tons of hours that was rode hard and put up wet and never an issue. My wife currently rides a 700 and its been good so far, but we are only at maybe 5 hours. I haven't heard anything as being a known problem for either of the two though.
Biggest problem I'm aware of was the tranny problem on the 01 model 660's... But even those were hit or miss. Ours was an 01, but must have had the good tranny cause it lived a long life with no issues.