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tamasuperstar

Yamaha YZ450F top speed of 90MPH + Is it possible?

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Is it possible to get a top speed of 90 mph to 100 mph from a new YZ450F?

If so, what size sprockets would be needed?

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Is it possible to get a top speed of 90 mph to 100 mph from a new YZ450F?

If so, what size sprockets would be needed?

 

Not sure about a standard 2014 but our Will Power tuned 04 can do 92 mph on 15/39 sprockets - that's running 17 inch wheels though.

Edited by 72degrees
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Not sure about a standard 2014 but our Will Power tuned 04 can do 92 mph on 15/39 sprockets - that's running 17 inch wheels though.

 

Thanks for the reply. Would the standard larger 19" rear wheel mean you would get a higher or lower top speed compared to the 17" wheel?

Edited by tamasuperstar

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Significantly higher. Very approximately 10% higher for a 19 inch rear according to the calculator I use, but the profile of the tyre also makes a difference for the same diameter of wheel.  Your best plan is to use a gearing calculator or spreadsheet with the appropriate ratios and rear tyre dimensions entered. I use this one: http://www.cunnington1.freeserve.co.uk/gearing_v12.xls

Then it's a question of what rpm you think it will be capable of reaching maxed out in top. Gear it way too high and it just won't pull it. Ours was dyno tested at 58 BHP when it was first built in 2004. I guess it might be a bit down on that now because as far as I know it has never been rebuilt since then. Seems the 2014 is around that figure out of the box. So mid 90's should be well within reach for a 2014 from our experience. Given a long enough straight 100 should be achievable - though aerodynamics will become more of a factor. We gear pretty much for max top speed at just beyond max power rpm rather than at the limiter, to suit the courses (speed hill climbs) we run at (particularly as it's only a four speed box). 92 is the best we have managed so far through a speed trap before running out of straight,
 
Others may be able to report how the standard steering geometry and suspension behaves at high speed. Our supermoto setup 04  has been lowered and fitted with Scar triple clamps). Then there's stopping it from 90+ ;)
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100 + on a built 08 Wr 450. The front wiggles like hell. Can't get down on the bars. Steering damper is a necessity. But don't have one yet. Needs mods if you run 13mm triple clamps.

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I see this post is fairly recent I ride a 04 yz450 and run 14/48 with the 4 speed trans long story short got pulled over 11 at night by county cop clocked at 93 mph!! still had little throttle left too lol....usually don't push that far but when it dark out gotta get home lmao

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+1 on the front will get you into the 90's.  Stock will do mid to high 80's.

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Why in the world would you want to hit 100 on a YZ450?

Out here in the California Desert I find my YZ geared for about 95 is perfect for me.  With wheelspin on the dirt I rarely if ever see top speed but it makes the bike way more rideable for most of the terrain without screaming the piss out of it.  I have an 11 I bought used and the first weekend I took it had +1 on the rear and I was bouncing of the limiter all day long.

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I race flat track and at Springfield mile we are easily doing 100+ mph on 450's. In quafiling in 2012 the top competitor quailified at an time 37.057 on a Honda 450.

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I race flat track and at Springfield mile we are easily doing 100+ mph on 450's. In quafiling in 2012 the top competitor quailified at an time 37.057 on a Honda 450.

 

I will do the math for you:)  97MPH AVERAGE around the 1 mile oval.

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Out here in the California Desert I find my YZ geared for about 95 is perfect for me.  With wheelspin on the dirt I rarely if ever see top speed but it makes the bike way more rideable for most of the terrain without screaming the piss out of it.  I have an 11 I bought used and the first weekend I took it had +1 on the rear and I was bouncing of the limiter all day long.

 

I cured that problem by crossing the gear box with parts from a WR:

http://www.thumpertalk.com/topic/1050577-hybrid-yz450wr450-desert-gearbox-06-09/

 

http://www.thumpertalk.com/topic/954114-wr-4th-5th-on-a-10-yz450f/

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+1 on the front will get you into the 90's.  Stock will do mid to high 80's.

I was thinking a 15 on the front and a 48 on the rear to give me a top speed around 100mph on the 2015 YZ450F. Do you think that sounds about right or would you suggest going lower on the rear sprocket?

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I was thinking a 15 on the front and a 48 on the rear to give me a top speed around 100mph on the 2015 YZ450F. Do you think that sounds about right or would you suggest going lower on the rear sprocket?

The problem is that with the close ratio 5 speed 1st gear will be really really tall.  But you will break a 100 with that.

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The problem is that with the close ratio 5 speed 1st gear will be really really tall. But you will break a 100 with that.

Hi y'all I'm new to the yz threes my 13 will easily crack 100 mph.

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Assuming it would pull to the rev limit, and assuming you eliminated all tire slippage, your '13 would top at 99 mph.  But it won't do either of those things.  In stock trim, they fall off pretty hard above about 10,600 (or lower, depending on the map), which takes the rear wheel driven speed to 91 mph.  Then, under the best traction you could hope to get on a dirt surface, you might keep the tire slip down to 10%.  Factoring that in, and you're down to 82 mph, which is about what they're capable of.

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I believe we were hitting 119 mph on the miles with the 450 and 109 with the 250  .on the road race track in florida we were beating an aprilia 125 ex factory race bike and the aprilia riders  gps showed 137 mph

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