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Old 08-15-2012, 12:24 PM   #16
IheartmyNx
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Originally Posted by fightinggoat View Post
the fzr250 made somewhere around 48hp, that has yet to be beaten by any other 250. That would be a fun motor to have in these bikes, would surprise a lot of people for sure.

Sans a 20,000 rpm powerband, right?

The VTR250 is 13,000.


Not too practical for anything less than track or bouncing it off the rev limiter everywhere you go.


NX250: 70.0 64.8 mm (2.76 2.55 in)
Fzr250: 48.0 x 34.5 mm (1.9 x 1.4 inches)
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Old 08-15-2012, 01:02 PM   #17
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i got the info off wikipedia
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Old 08-15-2012, 01:40 PM   #18
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Horsepower does'nt matter in drag racing, it's all about torque as that is what controls acceleration, horsepower is just the measurement of work being done at a certain rpm, the more hp the more work an engine can do and the faster the top speed can be, but it plays no part in acceleration whatsoever.
Not sure Mr. Newton would agree, RedRaptor22!

Horsepower and torque of an engine are related:

Horsepower, as beezer pointed out, relates to work (force X distance) per unit time. Torque has no time component. One horsepower equals 550 lbs force X 1 foot per second, or 33,000 lbs force X 1 foot per minute; since rotational speed is expressed in revolutions per minute, the figure, 33,000, appears in the formula.

Simplifying the forumula, power (hp) = (torque (lbf-ft) X rpm)/5252

Conventional physics considers acceleration proportional to power.

Googling "torque vs. horsepower" produces a confusing, overwhelming number of hits.
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Old 08-15-2012, 02:10 PM   #19
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Max speed per THE LAW in this state is 65 anyway...
Wha...? Uhhhh, ummm, when did this happen? Damn, gonna have to back it down a bit from now on.
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Old 08-17-2012, 09:32 AM   #20
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Not sure Mr. Newton would agree, RedRaptor22!

No, but Lingenfelter would.

"Horsepower sells cars, torque wins races"
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Old 08-17-2012, 10:33 AM   #21
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Wha...? Uhhhh, ummm, when did this happen? Damn, gonna have to back it down a bit from now on.
Yer telling me... 120/70, 60/45 and a 46/35 in the last month.

Other than that it's been 3 years since my last "speeding" ticket... (They always come in 3's)

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55-8-152. Speed limits -- Penalties.

(a) Except as provided in subsection (c), it is unlawful for any person to operate or drive a motor vehicle upon any highway or public road of this state in excess of sixty-five miles per hour (65 mph).

(c) On all controlled-access highways with four (4) or more lanes, which are designated as being on the state system of highways or the state system of interstate highways, it is unlawful for any person to operate or drive a motor vehicle or a truck at a rate of speed in excess of seventy miles per hour (70 mph). In the left-hand lane of all controlled-access highways with four (4) or more lanes, which are designated as being on the state system of highways or the state system of interstate highways, it is unlawful for any person to operate or drive a motor vehicle at a rate of speed less than fifty-five miles per hour (55 mph).



...
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Old 08-17-2012, 01:18 PM   #22
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No, but Lingenfelter would.

"Horsepower sells cars, torque wins races"

When did lingenfelter start racing 250 thumpers?
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Old 08-17-2012, 06:08 PM   #23
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Sorry, guys been too busy to look up all the specs and compare, if someone wants to gather up the info and post it then great, otherwise it will have to wait a little while longer.

So, anyone have any comparison experience riding both a honda rebel and any of the 250cc dual sports?
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Old 08-17-2012, 09:13 PM   #24
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Originally Posted by fightinggoat View Post
So, anyone have any comparison experience riding both a honda rebel and any of the 250cc dual sports?
Generally we stay away from Rebels.
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Old 08-18-2012, 01:22 AM   #25
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Well not having much experience with the smaller ones I would say probably the Wr250, it's the only one I've ridden other than a beat to hell old Xr250 and it'd probably knock the bold new graphics right off the honda I rode.

But you can figure it out scientifically with some of that math stuff, just look up the torque numbers and weight on each, figure how much the power to weight is and the one with the highest torque to weight will win with the correct gearing...being a simple mod like you stated is acceptable.

Horsepower does'nt matter in drag racing, it's all about torque as that is what controls acceleration, horsepower is just the measurement of work being done at a certain rpm, the more hp the more work an engine can do and the faster the top speed can be, but it plays no part in acceleration whatsoever.
Assuming that it is not a single gear race, horsepower rules the game.
Picture this.
We have any bike with a super duper CV transmission box and we measure acceleration through the ratios. The race starts with the lower possible ratio in the CV box. The revs climb (ratio hasn't changed yet) till redline (max power point). During this sweep, max acceleration will be had at the revs of max torque since the engine force is greater at that point. However, after redline is reached, max possible acceleration is attained if we keep the motor at the max power point and change the ratios thereafter and not by keeping the motor at the max torque point.

Moral of the story is that torque is good instantaneously and power is good on the long run. A 1/4 mile race (or any race) has to do with the 'long run'.
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Old 08-18-2012, 03:25 PM   #26
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Originally Posted by fightinggoat View Post
So, anyone have any comparison experience riding both a honda rebel and any of the 250cc dual sports?


I have a feeling you're looking at hp #'s and NOT the rpm they are generated at.


Also, liquid cooling vs. air cooled are very different altogether despite what cc's they are.

The Rebel for instance is air cooled and has two tiny pistons much like the liq. cooled Ninja 250 but not similar at all to a thumper.


We can do this all day but it's useless if you keep going by hp #'s (which is higher?) but not the rpm's they are generated at.


Compare a 4.3 Chevy to a 4.3 Ferrari... That might be a start for you. Both the same "size" but much different torque curves...

You could even put the same compression and ignition FROM the Ferrari into the Chevy, but it still wouldn't make, or even come close to making the same power the Ferrari does.


The new Turbo Cummins 6.7L only has a measly 350hp...

Well how come the 6.2L in the SC Corvette has 638?

Why not just put Corvette engines in the HD trucks? They have more power?
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Old 12-22-2012, 02:08 AM   #27
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Btw: can anyone who has ridden a rebel and a dual sport 250 like the ones in this thread tell me how they compare in terms of acceleration? My rebel was a dog, but it was my first bike, I have since come off much bigger bikes and want to get a little ds for fun but dont want to be bored with it in a month like I was with the rebel, felt like I was riding a scooter shaoed like a small motorcycle, lol.
I took the msf course on a 250 rebel (not sure of year) and own a 2004 klr 250

the rebel was WAY slower in acceleration
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Old 12-22-2012, 03:18 AM   #28
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Originally Posted by IheartmyNx View Post
No, but Lingenfelter would.

"Horsepower sells cars, torque wins races"
Quote:
Originally Posted by perterra View Post
When did lingenfelter start racing 250 thumpers?
and swiping Carroll Shelby's quotes? (some give credit to Ferrari, but they likely ride Ducati)

They're always related: hp=(torque*rpm)/5252
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Old 12-22-2012, 04:14 PM   #29
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Originally Posted by IheartmyNx View Post
I have a feeling you're looking at hp #'s and NOT the rpm they are generated at.

We can do this all day but it's useless if you keep going by hp #'s (which is higher?) but not the rpm's they are generated at.
The RPM at which the power is made is irrelevant when considering which bike is quickest. If you have two bikes of the same weight and torque but one has higher hp in a straight line race the higher hp bike will be faster (all other things being equal). The higher hp bike will rev higher (as shown by the equations/posts above) enabling the rider to stay in a lower gear for longer, that means that the engine can exert a greater force on the road over a longer time (which as is happens is the definition of power).

As has been stated above, torque is important for in gear acceleration but that's not what this thread is about.

Quote:
Originally Posted by IheartmyNx View Post
The new Turbo Cummins 6.7L only has a measly 350hp...

Well how come the 6.2L in the SC Corvette has 638?

Why not just put Corvette engines in the HD trucks? They have more power?
You're point has nothing to do with this thread. The Corvette engine can rev higher to make more power. The truck engine is built for low end torque and super long service intervals.

I know where you are comming from but the OP asked which bike is quickest, not which bike can I lug around all day without changing gears.
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Old 12-22-2012, 04:32 PM   #30
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That would be my bike.

Quote:
Originally Posted by fightinggoat View Post
Ok, I know none of them are fast, this is just to settle an argument between friends, of the older dual sport 250cc bikes, which is quickest to 60mph with stock gearing and equell basic power mods, no big bore kits or anything like that. Newer bikes dont count, just the 250's that are available to everyone on the used market, I.e. klr250, dr250, supersherpa, xt225, ext. Must be street legal out of the box and four stroke only. The only 250 I have ever ridden is a stock honda rebal, and man it was slow, so let the fun begin! y
My vote goes to klr250 just because of the high compression ratio, I have never riden one so cant say for sure, my buddy says xt225 cause of the weight. What say you?
Please keep this thread fun, its a goofy topic just because, no need to pick it apart.
The answer of course is my 2003 KLR250.

In all semi-seriousness though, I'd say the first year KLR250's, or the early XR250R's. Both were probably realistically making around 23-24 rwhp, and both weighed in around 290-300-ish, give or take 10lbs.

My 2003 KLR250 really is pretty quick. I've re-jetted, drilled the top of the airbox, and installed an FMF Q4 can and UNI air filter. I've also installed a smaller countershaft sprocket. When I want to "make a statement" at a redlight, I rev it up to a steady 2300 rpm and let the clutch out "briskly" as the light turns green, and I usually cross about half the intersection with my front wheel about a foot off of the ground. This old bike has about 27,000 miles on her, and she seems to run better as she gets older
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