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- Jake -

What rear wheel HP for a '03 WR450?

12 posts in this topic

My '03 WR450F is in the DynoJet shop to get the jetting checked and an overall health check - because I've always felt that it doesn't make the power a 450 should.

Hopefully the guy will call me tomorrow to let me know what he's found.

Do any of you guys know how much rear wheel HP should one of these bikes should make on a dyno? I might get them to dyno it if they can't find anything wrong.

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Dude, dyno numbers on anything other than the same dyno mean absolutely nothing. Any dyno is only as accurate as it's calibration factor and most dyno tuners run them high so you think your bike makes all kinds of power. It's all math, and unless you are there at the same exact time, place, temp, pressure it's all relative.

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+1 million. My friend hangs out on the Subaru WRX forums, and dyno threads get real nasty real fast.

Dude, dyno numbers on anything other than the same dyno mean absolutely nothing. Any dyno is only as accurate as it's calibration factor and most dyno tuners run them high so you think your bike makes all kinds of power. It's all math, and unless you are there at the same exact time, place, temp, pressure it's all relative.

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+1 million. My friend hangs out on the Subaru WRX forums, and dyno threads get real nasty real fast.

My good friend builds and designs software (as well as installs and calibrates) for a well known engine dyno company and it's amazing what all goes into making what is read match what is actually going on. And with the addition of a decimal point in software, you can make a 49cc scooter look like a 150hp monster. Ok, that's a little far, but the lengths people go to for a reading of 3 hp on the top end.....it's crazy.

Air pressure, elevation, time of day, humidity, tire wear; all factors on the same dyno. You throw 2 different ones in different locations, not even an apples to oranges comparison.

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What's with all the lame "I know more about dynos than you do." stuff?? :)

He was just looking for a good ball park number of what his bike should produce. Somewhere in the mid 40s is about right for a wr450f.:)

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What's with all the lame "I know more about dynos than you do." stuff?? :)

He was just looking for a good ball park number of what his bike should produce. Somewhere in the mid 40s is about right for a wr450f.:)

Correct, but what we a telling him is that ANY dyno number you get, vs. what I got vs. whatever is NOT an apple to apples compare.

The ONLY number that means anything is a number for a similar bike on the same dyno. I can make sny dyno read any number by a simple mathematical number change. My 954 read 142 on a dyno where I lived in Madison, and 128 on a dyno in Tenneessee. See what were getting at? If i didnt know better, I'd think I had a sick bike, when in reality the second dyno was way out of calibration.

Dyno's rarely get calibrated, and when they do it's almost never by a factory tech. Your far further ahead if your looking for an out-of-the-blue number to go to a place that works with bikes simlar to yours and ask them.

Or do and actually learn something....so instead of this guy thinking 35 means his bike is way low and spends $1000 on an unneeded rebuild (or at 48 his is WAY stout when it's actually sick) he may know to take the numbers at face value.

Mike

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If someone wants to check the health of their bike, they should spend the money on a leak down test.

If you want to see if an engine modification works, put on a near bald street tire, pumped up to 35 psi, dyno the bike before. Then using the same dyno, same operator, same air density, test after the modification. Then you will know the approximated percent of success you had. Anything else and you are blowing smoke up your butt.

For example, I did all this with a Drz a few years back. Stock I got 33Hp. E cams, FCR carb, I got 39. Added Yosh Ti pipe, got 44. Big bore, stroker, wild RHC cams, I got about 52. Same dyno, same operator, same air density. The Hp numbers stock were typical for a stocker so it is somewhat safe to assume that the subsequent ones were valid however, the only honest way to look at the numbers was by a percent improvement.

Edited by William1

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Correct, but what we a telling him is that ANY dyno number you get, vs. what I got vs. whatever is NOT an apple to apples compare.

The ONLY number that means anything is a number for a similar bike on the same dyno. I can make sny dyno read any number by a simple mathematical number change. My 954 read 142 on a dyno where I lived in Madison, and 128 on a dyno in Tenneessee. See what were getting at? If i didnt know better, I'd think I had a sick bike, when in reality the second dyno was way out of calibration.

Dyno's rarely get calibrated, and when they do it's almost never by a factory tech. Your far further ahead if your looking for an out-of-the-blue number to go to a place that works with bikes simlar to yours and ask them.

So stop being a douche don't freakin' read it.

Or do and actually learn something....so instead of this guy thinking 35 means his bike is way low and spends $1000 on an unneeded rebuild (or at 48 his is WAY stout when it's actually sick) he may know to take the numbers at face value.

Mike

I didn't mean to offend:bonk:. Sorry. I do understand how dynos work and that there is some arithmetic involved. And, yes it is good to know that there will be differences from one dyno to the next.

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The accuracy also has a lot to do with which type of dyno is used (Eddy Current, inertial, etc.)

On a Dyno-Jet Inertia Dyno my CBR1000RR, run 5 times, back to back, gave readings + - 5hp. The "butt sniffer" gas analyzer was reporting the same emissions and EGT all 5 runs. I always try to make any change the same day or even during the dyno session and if not possible, the same time of year with as close a Baro and Humidity/Temp as possible for comparison. Same dyno, same day, same temp, same baro, same humidity, if any of these varies even a small amount the numbers will be skewed horribly.

I also find that if you hop up and down on one foot while rubbing your tummy you get a free 5hp (you have to be video recording tho, or it doesnt work for some reason)

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