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Discussion Starter · #1 ·
Recently I read a lot of posts about tuning thr r3, which also showed dyno stats. What caught my attention was the fact, that basically all of the stats said, that the r3 stock model has only in between 35 to 38 hp. Yamaha on the other hand claims 42 hp. Aren't we getting scammed? In europe at least for cars, there is a law that the hp should not vary more than +/- 5%.

And if this is true, is it possible to return the r3?
 

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There is horsepower that the engine produces at the crank (bhp), and then there is horsepower at the wheel (whp). Basically, power is lost when it eventually reaches the rear wheel (physics). It isn't really a scam because manufacturers always list BHP. Dynos measure horsepower (more or less) at the wheel (whp). It doesn't matter which motorcycle, it doesn't matter which car, it will always be like this. Always.

The manufacturer isn't lying. It is basically following a tradition set forth by auto manufacturers long, long ago.

Oh and knowledge is very important. At least now you aren't ignorant regarding this information.

Also it should be noted that many aspects of life is this way, so get used to it.
 

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Discussion Starter · #4 ·
There is horsepower that the engine produces at the crank (bhp), and then there is horsepower at the wheel (whp). Basically, power is lost when it eventually reaches the rear wheel (physics). It isn't really a scam because manufacturers always list BHP. Dynos measure horsepower (more or less) at the wheel (whp). It doesn't matter which motorcycle, it doesn't matter which car, it will always be like this. Always.

The manufacturer isn't lying. It is basically following a tradition set forth by auto manufacturers long, long ago.

Oh and knowledge is very important. At least now you aren't ignorant regarding this information.

Also it should be noted that many aspects of life is this way, so get used to it.
Thank you very much for the long and good answer! You really cleared things up for me.
 

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Yep, the devil is in the details. Ya gotta look, yamaha claims 42 BHP. That's brake hp. Brake HP is measured at the crank, not at the wheel. NO manufacturer advertises their horsepower at the rear (or front) wheel. Car or bike.
 

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Jay knows what he's on about!

Another note is: on average chains lose about 11% of the power when transferring it to the rear wheel.

42BHP * (1.00-0.11) = 37.38WHP

Just a rough way of going about it.


Sent from my iPhone using Tapatalk
 

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yeap.. it is a "reality check"... gladly, that situation of power lost from engine to wheel is being applied for every car, motorcycle, etc... :)
 

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This plus the drive train loss on a car is *typically* around 15%. So take the specs and subtract 15% and you'll get closer to the true hp at the wheels for a car. Drive train loss can be even higher in some cases (AWD for example) so sometimes you can do 20%.

But I've also seen situations where hp figures are likely much lower than stated. For example, VW GTI's always seem to show dyno figures that are much higher than you would expect. So either the drive train losses are lower than you think or the hp numbers are higher than stated.

https://thegarage.jalopnik.com/2015-gti-might-be-making-significantly-more-power-than-1683694189
 

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Thank you very much for the long and good answer! You really cleared things up for me.
I should clarify and apologize for one of my comments in there. I was irritated by the subject- the deception or non-transparency. Unfortunately the subject at hand got me sort of angry, and no anger was meant to be directed to you. I hate things like this. The world would be so much better if everything was just reality on reality's terms. It would be a step to a better world if manufacturers can just put on their specs the wheel horsepower from now on. It is 2017 and we still have to deal with this sort of spin. Oh well, what a BS world we are still living in.
 

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I should clarify and apologize for one of my comments in there. I was irritated by the subject- the deception or non-transparency. Unfortunately the subject at hand got me sort of angry, and no anger was meant to be directed to you. I hate things like this. The world would be so much better if everything was just reality on reality's terms. It would be a step to a better world if manufacturers can just put on their specs the wheel horsepower from now on. It is 2017 and we still have to deal with this sort of spin. Oh well, what a BS world we are still living in.
No, that would not be a good idea because wheel hp can vary a lot for the same vehicle. It's influenced by tires, tire pressure, oil, environment where it's being measured, weight in the car, as well as some variables with the chassis dyno itself (bearings, lubrication, etc.). Way too many variables. With an engine dyno, you have a lot less variables and you get the direct output of the engine. It's much more reliable. Someone that knows how to operate a dyno well can put a motorcycle on it and measure 100 hp one time and then next time change some settings and it would read 110 hp even though nothing was changed on the bike at all.

There is a very good reason why manufacturers still do it the way they do. It's not just for marketing reasons like some people think.
 
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