Is it the higher compression? Lighter?
I am new to this forum so maybe I just don't get it. The Raptor has dual carbs and has 210cc's on the YFZ. The YFZ is less than 50lbs. lighter than a Raptor. 50lbs! That could easliy increase as the rider adds gaurds, bumpers, nerf bars, ect...

A friend of mine just bought a completley stock'05 YFZ 450 and he's talking sh@t that he can out run my '05 raptor w/ full yoshi exhaust, k&n, and dynojet kit. Do you guys think I've got anything to worry about?

Thanks for the replies in advance.

 

Dunno about your friend and you racing but the YFZ is lighter and has a better designed motor. Its motor is on the bleeding edge designed to use everything it has to its fullest. Raptor motor they just relaxed and let it fall on its displacement for its power. When you think raptor motor think car motor, designed efficently but nowhere near eeking out its potential and probably never will due to design. When you think YFZ think sport bike. Motor tediously designed to eek out every little bit it possibly can while still remaining reliable. Race bred motor.
It would probably be "near" its max if we didnt do things that took it out of the restrictions it was designed within. IE, more displacement, different fuels, cams and portwork aimed at pure topend, etc...

 

It has a short stroke and double overhead cams it revs fast so it accelerates quickly and is 50 pounds lighter this is at least my understanding, i'm sure someone will fill in any gaps. I am pretty sure with your mods you don't have to much to worry about. Besides you ever sit on one of those? I felt like a damn gorilla on that machine, knees up over the tank and the seat? I understand they finally put some padding in there but for my money it had to be a little bit comfortable. I would let him keep talking though it is always better that way.

 

Does anyone know the HP of a stock YFZ, or better yet, a line graph showing at how much power and tq is created at what RPM? I believe the peak HP of a stock raptor is at 6,500rpm @ 35.6HP.

 

Its about 36hp.

 

the yfz is the most power to weight ratio quad out there... it runs like a 2 stroke but in 4 stroke form... with your setup you should beat him i would say since you have mods done to it but however your buddy that has the yfz does the free cam mod and he should pull away, its not all on the quad either its on the rider as well when racing... and the weight difference is huge and style of the quad... lok are your rear axle and then the yfz not so much top heavy

 

Multi cams makes the biggest difference. The YFZ is designed to rev and rev fast. Super-light internal engine components, super-light chassis.

The 660 is a torque monster, but makes no where near the same HP numbers.

Even with your mods I would be worried if he can ride. He may just run right with you no problem.

 

good call SS!!!!!

 

Why worry? Did you bet pink slips? Only speaking from my experience, the 450 will spank the Raptor off the line 9 times out of 10 simply because the track/holeshots is what it's designed for - frame and engine wise. If you're running a full 1/8 mile and you're a competent rider, you'll at the very least catch up with him.

Forget the 210cc's nonsense. At some point they matter of course but just comparing that factor in this case doesn't work. That's like a Pullmyass 800 spanking the 450 cuz of the 310cc differential. Although I will admit, damn that big lug is fast for its weight.

 

If your running without the lid and your jetted right you should have no problem taking a stock YFZ.