Spec horsepower vs dyno results

[Boyca]

Hey all,

Recently I've been seeing some dyno results from people around here and elsewhere and the recurring thing I notice is that the dyno'd horsepower seems to be around 62.

Now why would Yamaha advertise their bike with what is it, 72 horsepower when it's almost 15% less in reality? I find it rather shady and I was a bit bummed out when I read about it. I'm curious if there's any reasoning behind it.

[Ray Ride4life]

Manufacturers almost always advertise with crank horsepower, Dyno measures at the wheel.
On average there is about 17% loss in the drivetrain between the crankshaft and the rear wheel.
In your calculation it is in fact not a 15% less but 2% win.
2% doesn't seem a lot but remapping is not always about gaining horsepower but especially for offroad use more about driveability and control.

[RideID]

It is standard industry practice, same for the automotive industry.

[Boyca]

55 minutes ago, Ray Ride4life said:

In your calculation it is in fact not a 15% less but 2% win.

What do you mean exactly with a 2% win? But thanks for clarifying how they measure it.

[Ray Ride4life]

You stated 15% less horsepower between the dyno results and what Yamaha stated.
I explained that Yamaha states the power at the crankshaft and the Dyno on the rear wheel.
The drivetrain (every moving part between the crankshaft and the rear wheel) takes away about 17% of the power.
Because you came with 15% less power between what Yamaha states and what the Dyno says and the average loss of 17% in the drivetrain assuming it is after some adjustments this means that Dyno shows a 2% increase in power and not a 15% less of what Yamaha stated.

[Aleksandar13]

I've got a beer opened up just to see where this is going ... ... The good old Dyno thread ... Keep them coming ... Mine made 76whp with loads of mods

[Liquidape]

6 hours ago, Boyca said:

Hey all,

Recently I've been seeing some dyno results from people around here and elsewhere and the recurring thing I notice is that the dyno'd horsepower seems to be around 62.

Now why would Yamaha advertise their bike with what is it, 72 horsepower when it's almost 15% less in reality? I find it rather shady and I was a bit bummed out when I read about it. I'm curious if there's any reasoning behind it.

What does the HP number matter aside from Dick waving rights if you like how the bike works?
Chasing peak HP on a bike like the T7 is kind of missing the point of the bike. 

 

[Boyca]

37 minutes ago, Liquidape said:

Chasing peak HP on a bike like the T7 is kind of missing the point of the bike. 

And you're missing the point of my post, I'm not hp chasing at all. I was simply curious as to why the gap between the specs online. It's been explained to me so that's it, I'm happy with what I got.

[TimeMachine]

16 minutes ago, Boyca said:

And you're missing the point of my post, I'm not hp chasing at all. I was simply curious as to why the gap between the specs online. It's been explained to me so that's it, I'm happy with what I got.

Yours was a fair question. It just caught most of us by surprise because this really is industry standard and we dont know any different. No manufacturer quotes rear wheel horsepower.

 

And dyno results are pretty flaky anyway, with some tuners happy to show crank horsepower or "uncalibrated" horsepower rather than a true calibrated reading. And tires can make a difference too, with heavy ADV tires tending to suck power on the dyno. If you want the truth then you have to go to a reliable source that uses the same calibrated dyno and tests in the same conditions across all the different bikes. The best examples are Cycle World and Motorcycle.com. They also weigh the bikes fully fueled, which solves that other bullshit factor of manufacturer quoted weights.

 

Here is an example from Motorcycle.com comparing claimed:

     90hp, 229kg (503lb) wet BMW 850 GS

     94hp, 189kg (417lb) dry 790 Adventure R

     94hp, 201kg (443lb) dry Tiger 900

 

To actuals (BMW,KTM,Triumph):

      

 

 

https://www.motorcycle.com/shoot-outs/the-middleweight-adventure-triad

 

Just note that these are "as ridden" so watch out for things like extra bars that the 850 and Tiger were fitted with.

 

As always, keep you bullshit filter on.

[Boyca]

Thanks for the insight @TimeMachine , it's interesting to see all the factors that come into play.

[Wintersdark]

3 hours ago, TimeMachine said:

Here is an example from Motorcycle.com comparing claimed:

     90hp, 229kg (503lb) wet BMW 850 GS

     94hp, 189kg (417lb) dry 790 Adventure R

     94hp, 201kg (443lb) dry Tiger 900

 

To actuals (BMW,KTM,Triumph):

      

 

 

https://www.motorcycle.com/shoot-outs/the-middleweight-adventure-triad

Good lord, +49 lbs on the BMW that was supposedly wet weight?  +50 and +60 for the KTM and Tiger too... Oof.  Now I want to get my Tenere on a scale.