True Horsepower- an inside look at honest horsepower

[delusionised]

May 2005 Dirt Bike Magazine article "True Power-An Inside Look at the Real World of Honest Horsepower" Pg 84, shows a dyno graph comparing an 1994 KX500 VS. 2005 YZF450, wonderfull wonderfull graph, The stock KX peaked at 60hp! STOCK!  @ 7,000 rmp and the YZF a mere 49@ 8'500 rpm Ha, I love it, But tell me why the hell these 450's hang with us? I dont get it, Hmmm....Check this out though, under the dyno chart there is some text and it says, and I quote...

"Want a dose of reality? All the fanfare that the new four-strokes are getting shows that they still are not in the realm of true horspower compared to the 500 two-stroke. You wonder why ty davis' of the world love the KX500; Look no farther than this. They not only made monster power early in the powerband, they (the CR and KX were close) peaked out at at the 60- horsepower mark.


 Its like Danny LaPorte was saying," So lets see, after six years the big bore four-strokes are still heavier, slower and require higher mantenance than a decade-old design".  (500's)


Wish I could post the graph some how but I dont have the equipment. So everyone Kill the four-strokes!!!

[mikesmith]

The 4-stroke advantage is in tractable easy to ride power delivery (not as much skill as a big 2-stroke takes),2-stroke takes a skilled rider to go fast and not waste power or let the bike wear you out.4-strokes are here because of the EPA and manufacturers make more money in parts and dont forget the public "me to" mentality.

[Arigato]

The best thing to do is.....Own both!! I have a 450 for the track and the 500 for sand or when someone needs a slice of Humble Pie.

[GDubb]

Amen on the Humble Pie!  Friends wonder why i wont let them ride my bike,  and I'd rather they didnt find out why on my bike.  When I tell friends about how bad it is, I'm sure they all think I'm just talking out of my a** and I'm just stingy with my toys. Little do they know... I could be saving their life.

[musturbo]

Peak hp has never meant much to me.  Kinda like a stereo amplifier rated at 1200watts when   useable power is only  100watts.  anything under 5,250 rpm is torque, and that is where most of my bikes live, so I have always  looked for the tq ratings and area under the tq curve on a dyno sheet.     Th kx5  amazed me at how much power this bike makes off idle.  If it didn't need to be cleared by blipping the throttle I would swear this was the nastiest 4 stroke i ever rode!

[musturbo]

I know this is a car, but this is what I mean when hp  doesn't mean a whole lot.

[Minnetonka_Mark]

I saw the article about True Horsepower.  For me the key point was NOT the peak horsepower.  Instead, examine each of the graphs taking close look at the power output in the range just above idle, say 2K to 4K RPM.  I don't have the graphs in front of me as I'm writing this, but I recall that the KX500 engine is COMPLETELY in a league of its own just above idle.  Just above idle the engine output very quickly reaches 40HP.  Then it gradually builds to 60HP.  NONE of the other large displacement engines make much more than 20HP just above idle.  Take your properly jetted KX500 out to the paved street in front of your house, i.e. someplace where the tire hooks up well, and twist the throttle just a bit while in second gear.  You'll immediately feel that HP surge.  When you're riding on dirt the rear wheel just throws dirt so you don't feel the low RPM power output as much.  The KX500 has an amazing engine.

[delusionised]

I saw the article about True Horsepower.  For me the key point was NOT the peak horsepower.  Instead, examine each of the graphs taking close look at the power output in the range just above idle, say 2K to 4K RPM.  I don't have the graphs in front of me as I'm writing this, but I recall that the KX500 engine is COMPLETELY in a league of its own just above idle.  Just above idle the engine output very quickly reaches 40HP.  Then it gradually builds to 60HP.  NONE of the other large displacement engines make much more than 20HP just above idle.  Take your properly jetted KX500 out to the paved street in front of your house, i.e. someplace where the tire hooks up well, and twist the throttle just a bit while in second gear.  You'll immediately feel that HP surge.  When you're riding on dirt the rear wheel just throws dirt so you don't feel the low RPM power output as much.  The KX500 has an amazing engine.

key point for me is thats probably the last dyno we are ever going to see printed in a magazine    sad but true, sucks big time

[Ramski]

Let's not forget the pressure Yamaha and Suzuki put on the AMA to drop the 500cc nationals.  Like it's been said before.  It's all about money.  The only improvement they could really make to a two stroke motor was make it more eco friendly.  They saw a lot more potential for improvement in the four stroke motor, plus let's not forget the parts departments are making a killing.  Those 250fs are ticking time bombs and cost a fortune to rebuild if they grenade!

[Polar-Bus]

The 4-stroke advantage is in tractable easy to ride power delivery (not as much skill as a big 2-stroke takes),2-stroke takes a skilled rider to go fast and not waste power or let the bike wear you out.4-strokes are here because of the EPA and manufacturers make more money in parts and dont forget the public "me to" mentality.

VERY well stated. Ive owned both. Even though a KX5 peaks @ 60 hp, its VERY difficult to put that 60 hp right to the DIRT. You average 450 puts out approx 10-12 less hp, BUT with the engine firing every 4 strokes instead of two, they are superbly efficient at putting traction down into the dirt. Traction being equall, a KX5 should spank the snot out of a 450 4 stroke. BUt in a race there are always so many variables that change the overall outcome.

[demographic]

VERY well stated. Ive owned both. Even though a KX5 peaks @ 60 hp, its VERY difficult to put that 60 hp right to the DIRT.

Put the power down on the road instead