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DesertRacer2

101 MPH on a 2007 YZ450F

29 posts in this topic

My brother and I went to El Mirage today in CA. The weather was nice and our bikes ran great. We both have 07 YZ450's. Our bikes are geared 15/48 for desert racing. On the lake bed, measured with a GPS , our bikes hit 101 mph. We tried it multiple times and the gps would keep recording 101 mph. Just thought you guys might find this interesting.

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Wow, so was it on the rev-limiter in 5th gear?
It would have needed to turn at or near 11K to reach that speed with that gearing, depending on how much rear tire slip was going on (there's always some)

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According to my gearing calculator, with 15/48 you should hit 109 at 11000 RPM. That will never happen because of several things, wheel slippage, aerodynamics and power falling off at upper RPM. 101 sounds reasonable. My 04 with that gearing would bang the rev limiter on the dry lake while still pulling hard but of course it was a four speed so it would be around 90MPH.

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Wow, so was it on the rev-limiter in 5th gear?

Yes, it was bouncing off the rev-limiter, however, I didn't hold it on that long.

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According to my gearing calculator, with 15/48 you should hit 109 at 11000 RPM. That will never happen because of several things, wheel slippage, aerodynamics and power falling off at upper RPM. 101 sounds reasonable. My 04 with that gearing would bang the rev limiter on the dry lake while still pulling hard but of course it was a four speed so it would be around 90MPH.
It depends on what you put in for a rear tire diameter. 27 inches gets you 109.36 at 11K, as you said.

Your '04 was not only a 4 speed, but had a primary ratio of 2.818 instead of the higher 2.652 that is used in the '05 and later models. That's roughly the difference of one full tooth on the front sprocket. The "on paper" top speed at 11.5K would have been 97.5, with no allowance for wheel spin.

Yes, it was bouncing off the rev-limiter, however, I didn't hold it on that long.
Anyone who doesn't think that the rear wheel slips at high speeds should consider this case. He hit 101 on the rev limiter, which we know is 11,500 rpm. At that RPM with the gearing he has, and a 27" tall rear tire, the rear tread speed was 114 mph. That's an 11% loss.

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Yes, I have been using a Scotts steering damper for 5 years now. I can't imagine riding without one now.

I really want to put one on my 08 pretty bad since I mostly ride desert and sand dunes with a little mountain trails thrown into the mix every now and again.

Hauling ass in the sand dunes gets kind of sketchy when it starts to get headshake in 4th and 5th gear.

I am torn between the scotts damper and the GPR damper but I dont have any experiance with either one on a bike. Have you ridden a bike with a GPR damper to compare to the scotts?

Thanks:applause:

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I really want to put one on my 08 pretty bad since I mostly ride desert and sand dunes with a little mountain trails thrown into the mix every now and again.

Hauling ass in the sand dunes gets kind of sketchy when it starts to get headshake in 4th and 5th gear.

I am torn between the scotts damper and the GPR damper but I dont have any experiance with either one on a bike. Have you ridden a bike with a GPR damper to compare to the scotts?

Thanks:applause:

I personally have not. However, a friend of the family had a YZ450 with a Scotts and a KTM 450 EXC with a GPR and he said the Scotts was superior. I have dealt with the staff at Scotts for many years and their customer service is great. Once, my damper had a little bit of black grease near the top of the armature, nothing major at all. I called them up and they rebuilt it for me at no charge.

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Notwithstanding the fact that their customer service is top notch, The Scotts is adjustable for overall resistance, for sweep (left and right independently), and only Scotts has a high speed damping valve, also adjustable. The difference they make is amazing.

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How fast is a 2007 YZ450 with a stock front sprocket and a 50T in the back?
On pavement, about 85 at the power peak, 92 or so at the rev limit.

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Dirt Rider put the '07s on a dyno and ran them to top speed. Here's their #s

CRF450R - 91

KX450 - 90

KTM 450 - 84

RMZ450 - 77

YZ450F - 84

The YZ gearbox ratios are spaced very evenly.

1st - 42, 2nd - 52, 3rd - 63, 4th - 73 and 5th - 84.

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