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Discussion Starter #1
In general, when a motorcycle manufacturer advertises their horsepower ratings here in the U.S., is it standard to use the horsepower at the crankshaft or the rear wheel?


Phatass
 

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From what I have been told, it's at the crankshaft. It sounds more impressive if they say 128 horse power than 100.
 

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Blowin' Smoke
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Example: '02 V-rod was advertised by HD and dealers at 115 HP. In stock form it was lucky to dyno (rear wheel) 100 HP. :blahblah:
 

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It's the same with cars unless they say 300 hp at the rear wheel which they don't so there is hp loss through out the transmission and shaft to the rear axle.
 

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If it truly is at the crank and since there are variances from same model bike-to-bike, I am curious as to what the acceptable deviation might be from the OEM stated versus production actual.
 

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Discussion Starter #8
OK, kind of what I thought.

So, next question. I have a factory rated 125hp at the crank on my DX. When I do the Stage II cam upgrade, and assuming I get 20 horsepower increase at the rear wheel as most have done and the bike is properly tuned, can I reasonably assume that I will have 150 horsepower at the crankshaft when all is said and done?

If this is so, and I'm pretty sure it is, it doesn't really place us that far away from top end horsepower of some of the higher end rice grinders. Now, no matter what, this bike will never be my old Kawasaki ZX-14. Nor do I want it to be. I just thought it was interesting that 150 horsepower is pretty damn respectable in the world of performance style bikes. Now if I could find 50-75 pounds to remove from the bike...


Phatass
 

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Major marine manufacturers, (Mercruiser and Volvo) now and have for the pat several years quoted prop HP readings.

Never really did like car, bike or boat manufacturers ever quoting anything else
 

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OK, kind of what I thought.

So, next question. I have a factory rated 125hp at the crank on my DX. When I do the Stage II cam upgrade, and assuming I get 20 horsepower increase at the rear wheel as most have done and the bike is properly tuned, can I reasonably assume that I will have 150 horsepower at the crankshaft when all is said and done?

If this is so, and I'm pretty sure it is, it doesn't really place us that far away from top end horsepower of some of the higher end rice grinders. Now, no matter what, this bike will never be my old Kawasaki ZX-14. Nor do I want it to be. I just thought it was interesting that 150 horsepower is pretty damn respectable in the world of performance style bikes. Now if I could find 50-75 pounds to remove from the bike...


Phatass
Respectable, maybe, damn fun for sure but at 180+hp and 4/500# the Crotch rockets will leave you standing. Don't forget you're assuming they are all stock, many have already done what you plan and more to their crotchets. At 200+ and stripped, they are just lickin' their chops.....assuming they can ride the damn thing.

If it truly is at the crank and since there are variances from same model bike-to-bike, I am curious as to what the acceptable deviation might be from the OEM stated versus production actual.
I read that they had an 8% tolerance, seems a bit high to me but that doesn't mean they actually have 8% variance, doesn't mean they don't but all builds do act and perform differently, all of them, any builder can tell you this.

OEM is ALWAYS at the crank. (A certain salesman at Lake Erie Harley needs to learn this also or at least realize WE know it.)
 

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I always call the manufacturers horsepower claim "brochure horsepower". It has no basis in the physical universe.
 

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I always call the manufacturers horsepower claim "brochure horsepower". It has no basis in the physical universe.
True! However, at least they are sure enough (or) brave enough to print their horsepower results. Of course there have been times where the claims were disproved, but typically the printed horsepower claims can be reliably used as comparative guidelines and are judged accurate (basis for this fact is that the claims can be reproduced using exactly the same parameters the manufacturer initially used) The guarantor to this is what we know as 'Truth in Advertising'. Cases have been lost when the claimant could not duplicate the advertised claims that attracted sales.
 

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I always call the manufacturers horsepower claim "brochure horsepower". It has no basis in the physical universe.
I believe the HP ratings more than the 1/4 mile times they claim. They probably made 100 passes with a horse jockey size rider to get low 11's. Manufacturer HP claims are way to easy to disclaim. I've seen 4 stock V's dynoed before the retune and given a 15% or so loss in the transfer I would say Harley is quite accurate.
 

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I believe the HP ratings more than the 1/4 mile times they claim. They probably made 100 passes with a horse jockey size rider to get low 11's. Manufacturer HP claims are way to easy to disclaim. I've seen 4 stock V's dynoed before the retune and given a 15% or so loss in the transfer I would say Harley is quite accurate.
Harley is probably more honest than most, although my "120 horsepower" Street Rod only put 102 of the aforementioned horses to the back tire, and that is with an "off road only" fuel map. Stock was even less.
I'm trying to remember what performance car had to be recalled about ten years or so ago because when the owners dynoed them they made significantly less than the manufacturer was advertising.
I believe what I see in magazine tests of real bikes on dynos and at the strip.
 

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Harley is probably more honest than most, although my "120 horsepower" Street Rod only put 102 of the aforementioned horses to the back tire, and that is with an "off road only" fuel map. Stock was even less.
I'm trying to remember what performance car had to be recalled about ten years or so ago because when the owners dynoed them they made significantly less than the manufacturer was advertising.
I believe what I see in magazine tests of real bikes on dynos and at the strip.
Keep in mind these magazines get paid thru advertising from the same people who's bikes they are testing. They are also given a "factory" bike to test.........outta the box factory????

I would say an 18-20 HP loss in the transfer is about average. Typically 15%, more for shaft drive and bigger wheels.
 

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Harley is probably more honest than most, although my "120 horsepower" Street Rod only put 102 of the aforementioned horses to the back tire, and that is with an "off road only" fuel map. Stock was even less.
I'm trying to remember what performance car had to be recalled about ten years or so ago because when the owners dynoed them they made significantly less than the manufacturer was advertising.
I believe what I see in magazine tests of real bikes on dynos and at the strip.
I believe it was the Mustang Cobra.
 

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i can remember when some cars making close to 500 hp were reported to have around 400 by manufactures. the people know what is faster than what but they were trying to hide it from insurance companies so they could sell their cars
 
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