KX Riders

Maintenance & Technical => KX250 / KX125 => Topic started by: 2006kx250 on July 22, 2007, 08:38:02 AM

Title: Horsepower ratings and power loss to back tire?
Post by: 2006kx250 on July 22, 2007, 08:38:02 AM

 :? I was just wondering about how much power loss percentage wise that you lose from the crankshaft to the rear tire.  An article in DirtRider Magazine (I think) said that the Dyno'ed horsepower in their 2006 2-stroke 250 shootout of the KX250 was around 47 horsepower.  My title that came with my bike showed 58.2 Tested HP which I assume is at the crank.  I find it hard to believe that you would loose 10 0r 11 HP.  This is like a 19% Power loss.  So is my bike above normal or was their bike just low on numbers or do you really loose that much?  Is the 58.2 HP a tested rating of just my bike or is it a average rating from Kawasaki just printed on all Titles of that model?  Anyone else have their titles handy to let me know your stated numbers?

Title: Re: Horsepower ratings and power loss to back tire?
Post by: gowen on September 10, 2007, 03:53:45 AM

I was going to guess about 20%. Sounds like that is what you came up with. There are so many factors coming right off the crank, from bearings, to multiple gears, to the sprockets, the chain, to the rear tire.

Title: Re: Horsepower ratings and power loss to back tire?
Post by: FactoryPhil on September 10, 2007, 04:07:45 AM

Kawasaki's HP numbers are measured at the crankshaft. The HP rating is not stated on my title for my 90 KX500 but I have a spec manual that states the power as 64.5@7,000rpm. I would guess that the stated ratings are an average of several test engines.

Title: Re: Horsepower ratings and power loss to back tire?
Post by: stewart on September 10, 2007, 08:33:02 AM

64.5 is crank hp on stock kx  500 at 7000 rpm