I was purusing the local yamaha dealer about gettting onto an 05 YZ450F and he told me that it was pushing 60 hp?! Thats rather impressive I said and he said yeah its 20 more than the YFZ450?! wow. can anyone confirm or deny these claims for me? :cry:

Your dealer was high or forgot to take his daily pill.

You're saying that the YZ450F (MXer) has 20hp more than the YFZ450 (quad)? I don't think I've ever heard anyone say that a stock YZ450F had 60hp, a little over 50 but I thought that was about it.

from reading the atv pages the YFZ has the exhaust cam timed like the WR's, so it will be lower on power output.

the 450 bike definately doesnt produce 60 hp and the quad is said to be about 10 hp less than the bike because the timing is retarded one notch and the more restrictive airbox and exhaust... not to mention its 10cc less in displacement.

cool thanks for the input. I thought it sounded a little off....

Not this argument again. Lets say this all together now... In Kalifornia the YFZ450 makes 39hp at the crank, that translates to about 30 at the wheels. The YZ makes 60 at the crank, this translates to about 49 at the rear. The Kali YFZ is plugged & restricted to meet green sticker requirements.

To my knowledge the rear wheel readings are some 35 vs. 48 hp.

So never 20 hp difference. Talking about SAE readings from combustion chamber is hypothetical and waste of time. What makes the difference is what you have on the wheel.

And sorry about my immature initial comment.

I liked it :cry:

To be nit picky, you're saying that the YFZ loses about 25% in the transfer to the wheels, and the YZF loses less than 20%? I've always heard that from the crank to the wheel is about 9-13%, not higher than that.....I would agree with the wheel BHP, but I think the crank numbers are a little high. I can't believe a chain drive would drop that much power. Anyone??

We need someone with skills and time to spare to hook the crank shaft directly to a dyno and give us the results. :cry: :cry:

Stuff like this always hapens in the sales department. They live in a different world.

I had my YZ450F dyno'd with a FMF Q and it got 48. So the 49 number sounds good to be with a non Q exhust. The Quad motor has mucy more FWW than the WR, and has more restrictive exhust flow. I've heard low to mid 30's on the dyno for it some several people that I trust.

In the end it all comes down to the rider, and the terrian. Certain places each will have it advantage.

You gotta have spot on jetting getting 48 with a Q. Bet you also did the motoman break-in. :cry:

You also need to remember that the YFZ quad is only 439cc. It is not a true 450 like the MX YZ.

You gain about 10hp by installing an aftermarket exhaust, removing the airbox restrictions and rejetting the quad. Like said, it is EPA'd.

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