ALL years YFZ and 700R are good. The earlier YFZ's had a few issues with battery charging and leaking water pump seals. All things easily repaired or upgraded. The main differences between the 2 are this

YFZ- lighter weight, sharper handling, better at jumping, stiffer ride

Raptor 700- reverse, plusher suspension, has a taller feel to it.

Stock the overall power/speed on both is close but the 450 makes up the cc difference by turning higher rpm. It is going to be a more maintenance intensive motor, meaning it needs more frequent oil changes, valve adjustments, and piston replacement(The pistons on the 450s are "pancake" style, not the jugs of a traditional 2 or 4 stroke.)

 

early year yfz's had a weaker rod design. 06 or 07 changed that.

 

thats what everyone says only i have had 0 prob out of my motor at all. change the oil very frequently. every 6or 7 rides now that i use amsoil full synthetic, that stuff is amazing. in order for u to determ which u want u have to ride both. Not just around a yard u need to really ride it when u test them out.

 

the yfz's are just bad *** bikes not to bash the raptor, but when i upgrade from my outdated warroir, i'm going with the yfz, rides better, deffinately handles better, has more power, and the power is more controable to me, but that is the way i like my bikes, don't like all your power to be down low, but when you womp on it i like it to go, not turn over j/k the yfz is definately balaced better though.
JMO

 

i have a raptor 700 and its the best all around quad i have ever owned. i can do everything from trail ride (a little harder on tight trails now with aftermarket suspestion). go to the track and not get whooped by 450s. go to the desert and get most 450s. with the ishock 5500 front end and a reworked back shock and durablue axle it does great on the whoops and hauling *** on glamis/gordens sand drags .

 

<div class="FTQUOTE"><begin quote>Originally posted by: Koopa

Yikes. 700's get hot quick and 450's get hot quicker. Tight, slow riding is not for the 450 it's to high geared. 700 can handle it a little better but not good. I know you said yammy but the air cooled Honda 400ex is the trail king if ya ask me.</end quote></div>

Explain to me how an air cooled bike is going to run cooler that a liquid cooled bike.

 

never had a problem with mine overheating.

 

I found my 660 wasn't much better than my very old and well used Warrior. Which was a disapointment after shelling out that kind of cash. The new 700's are a whole lot better. I'd reserve the 450 for racing... I know a lot of guys swear by them, and I admit I do not own one so I may be biased, but my experience has been that something that finely designed and tuned for the race track may be great in those conditions, but if you are not using it for what it is designed, then it becomes a real hand full. If trail riding is the big deal, speed usually is not a factor. Light weight and handling is important, and I doubt you will find anything better than the 450 iin that regard, but again it may be akin to using a thoroughbred to pull a plow... Decide on your riding style, and choose wisely. I know some will howl, but give the raptor 350 a try.. It is the old Warrior under all that new plastic, but they are good machines none the less.... these days, it is hard to get me off my 4x4 for trail riding. Comfort over speed for these old bones... You all will get there someday and understand what I mean...

 

Thanks for the good info guys. Sounds like I need to stay away from the 660 Raptor. Thats too bad. There are a lot of deals out there.