This has been an interesting thread. Some replies have made some very good points.

Having personally raced several Predators myself with my mildy modded YFZ I was less than impressed. Don't get me wrong, they only got beat by a 2-4 lengths at best. But one would think a motor with 60 more ccs would perform better than that.

I am going to cut and paste a post from another site I frequent. This post was made by a guy that builds and dynos all brands of sport bikes for a living. No biased at all. Pretty amazing information he had.

Again, the following are not my words. From here on is a cut and paste from another site.




How about a 40% advantage in power @ 4000 rpm for the YFZ?!!!
How about twice as much usable rpm than the Polaris has?!!! (nearly as much usable rpm as the Predator has rpm). I wish I would have scanned the power curves so I could have posted them. Maybe later.

The only time the curves converged was in the torque curve and only for a few hundred rpm and then only by a couple percentage points. And it was at the Polaris's peak torque point, which the YFZ was still climbing past.

And if the cam mod was done to the YFZ, STAND BACK Polaris owners, the closest the Polaris came was at it's peak where it was within 20% of the YFZ's peak.

The Polaris' peak hp came @ 6700 and lasted until 6900 before dropping off sharply @ 7500 to the rev limiter @ 9000 rpm. The YFZ in it's natural state of tune has a power delivery from roughly 3500 rpm to 10750 rpm, 7250 usable rpm. And by usable rpm I mean from when it will accept full throttle and hold that rpm under full load to the point where it doesn't have enough power left to pull itself forward anymore. The Predator, 4000 rpm to 9000 rpm is where it will rev too but is actually useless above 7500 rpm (the power falls off so quickly above that point it won't pull beyond that on the ground). So, it's actual usable rpm is from 4000 to 7500 or 3500 rpm of usable power.

Now figure in the cam mod to the YFZ. The 7% gain at peak throws the YFZ into a huge gain at the Pred's peak. What was just a 12% advantage for the YFZ turns into 19% and it's still got rpm left before the YFZ hits it's peak hp.

Suffice to say, if you line up against a Predator, unless it's been substantially modified (or has a bottle strapped to the side and even then that probably won't be enough either), fear not, for you are riding the baddest **** there.

Let me also say that the Predator looks to be based (almost exactly) on the 23 year old Kawasaki GPZ1100 cylinder head. They use what looked to be the exact shim bucket although it used 9.48 mm shims under the bucket, not 13 mm shims like the Kawi, and 4 valves not 2 obviously.

Besides having no bottom end power and no good spread of power and few usable rpm, it's HEAVY. Of course, I'm probably not telling you guys anything, you've most likely been there done that. But for me, it was my first encounter with the comparison on a dyno and the first time I have taken a Pred apart. Unfortunately, it won't be my last time. We're making cams for it. Which I might add, takes me an hour to change compared to 15 min for the YFZ and 25 min for the TRX450R.

 

60cc's larger... correct... but the raptor is 210cc's bigger... and still looses.
the 450 motor is alot different than the pred motor... smaller more compact and higher revving.

 

the YFZ is not a true 450. It is only 439cc. Whats Polaris gonna do when the cc's get to 450? I love threads like this.

 

true, its only a 439...
what polairs gonna do? i dunno... those 11cc's arent going to do much except make it the same as the honda and suzuki...

 

The zuki? when? where? do you have inside info? Turn the lights on for me.

 

last I knew the "Z" was still only 400cc for 05'

 

06... its not inside info... everyone knows about it... cept u i guess [img]i/expressions/face-icon-small-wink.gif[/img]

 

Oh, the 06, who knows if I'm alive that long, I hope to be around later this month for the yellow and black 05' LE YFZ![img]i/expressions/face-icon-small-smile.gif[/img]

 

ya, that thing looks nice.

 

439 divided by 350 =1.25 (YFZ) :499 divided by 415 =1.20 which is pretty close cc per lbs. In my experiences on asphalt the Pred took it (stock) on dirt I don't know: on sand I tied.