WR450 max power

Hey guys. I am perpetually impressed by the YZ/WR450. I was reading in the Febuary issue of Dirt Bike magazine, I came across a YZ450F flat track bike with 67 horsepower. I know that the WR and YZ are very similiar, excluding the 4-speed vs. 5-speed. I was curious how the owner of that YZ got so much power out of his 450. Since Yamaha doesn't post torque and horsepower numbers, I am curious of how much power the produce stock (WR and YZ) and how much torque. Not many people have dynomometers in their garages, anyone heard a power rating from a manual, or technician?

I came across a YZ450F flat track bike with 67 horsepower.

Did it say at the crank or back wheel ?.

If you ever seen the movie "On any Sunday" they explain it in there. If you havent I suggest you do cause its very educational. They explain that flattrack riders are on their own and do nothing but tear down their bikes engines and rebuild them to how they want them. Things from modifing little tiny parts to shave off ounces at a time, and have fractional horsepower gains. But in the end it all adds up to what wins the race. I read that article too and that guy is an engine builder. Check out that movie, its classic in the motorcycle industry.

Yamaha usually publishes the HP rating (from the crank) on the certificate of title.

Yes, I have seen "On Any Sunday" Flat track maniacs will sell their kids before they give up their bikes. Alright, coming back from my tangent; I realize what racers can accomplish by polishing a piston until it sparkles in the dark. As a result they get one more RPM, which is one more advantage over the opponent.

Hello, please could you advice me on the lower and upper rev.limits for the "Power Zone" on a stock WR450F?

Do you mean stock power or what you get out of it?

Timo McKeown

I mean stock power...for better performance/control and longer life cycle expectations for the engine, without making any modifications.

At this time I'm learning Enduro and just getting acquainted to this very new to me machine.

I think they are 37 bone stock . I think you get like 50 or so with all the free mods and a pipe and rejetted.

I have 52 and I have Stillmotor exhaust, ported head, Twinairgage, snorkel removed and jetted.

Next move is to get Vortex and do a special ignition curve on that.

So next dyno is on next wednesday. There we are going to dyno first all 10 curves and after that pickup the best ones and do some mods.

Timo McKeown

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