Questions about HorsePower and Torque on MX bikes.

[Braap257]

I'm just curious how much the average 250 2 Stroke makes in Horsepower and in Torque, compared to the big 450F thumpers?

Also, A buddy of mine who rides an 06 RM250 came over tonight and we were talking about how much power my YZ250 most likely made. I guessed anywhere around 44-46HP. He said thats too low and that his RM is makin like 55HP!! I immediately called Bull$hit. and he said with his exhaust setup "its a stock pipe with Pro Circuit shorty " that it wasn't an unreasonable number....  Now this kid has been ridin motocross for 4 years now. And I may be new. But I know aint no stock 250 "And his is. no motor work done" is gunna make 55 Ponies... Thats close to the numbers the old 500 dino's made right??? anyways, sorry that this took longer to explain than the original question lol. 

[JETZcorp]

It's possible that a weirdly-calibrated dyno might push those kind of numbers, but it sounds like a classic case of "bench dyno" to me.  Like when my neighbor claimed he used to have a Bultaco 500 (which, of course, was never made.)  Sounds similar to this "Pro Circuit Shorty" business.  Or like various characters in Super Hunky's book would say, "I used have onna them.  Went like a raped ape, she'd do a hunnert mile an hour in second gear on any slope!"  Yeah, sure.

The numbers I've heard for modern, stock 250s generally go from about 44 to 48.  The numbers I've memorized are 46 for the YZ, 48 for the SX, and an epic 53 for the MMX.  Not sure who is talking about rear-wheel horsepower and who (if anyone) is talking about brake horsepower, but that's just what's published.  I think that if someone is talking about crankshaft power, it'd be easy to guess who it is.  I still don't think it matters a whole helluva lot in the real world, though.

Torque, I couldn't tell you.  I could do some math to find that the torque is at the point of peak power, if I knew what RPM that was achieved at, but of course torque and horsepower peak at different revs so it would be meaningless.

[Braap257]

It's possible that a weirdly-calibrated dyno might push those kind of numbers, but it sounds like a classic case of "bench dyno" to me.  Like when my neighbor claimed he used to have a Bultaco 500 (which, of course, was never made.)  Sounds similar to this "Pro Circuit Shorty" business.  Or like various characters in Super Hunky's book would say, "I used have onna them.  Went like a raped ape, she'd do a hunnert mile an hour in second gear on any slope!"  Yeah, sure.

The numbers I've heard for modern, stock 250s generally go from about 44 to 48.  The numbers I've memorized are 46 for the YZ, 48 for the SX, and an epic 53 for the MMX.  Not sure who is talking about rear-wheel horsepower and who (if anyone) is talking about brake horsepower, but that's just what's published.  I think that if someone is talking about crankshaft power, it'd be easy to guess who it is.  I still don't think it matters a whole helluva lot in the real world, though.

Torque, I couldn't tell you.  I could do some math to find that the torque is at the point of peak power, if I knew what RPM that was achieved at, but of course torque and horsepower peak at different revs so it would be meaningless.

Yup I think 44-48 HP is reasonable for the modern 250's And with engine mods and work, I don't know what they could achieve even though it may make them pinging time bombs 

[JETZcorp]

As far as tuning and mods, I'd refer to some of the guys behind Project Two-50.  They've done some significant work and have become quite familiar with what various ins and outs do to an engine.  Of course some mods can cause pinging and shortened life and such, but that's mainly a result of too much heat and/or too much compression (the two are not unrelated).  It is certainly possible to generate massive amounts of power without causing detonation, either by finding extra power without increasing the compression or causing heat (better carburetion, more efficient flow patterns, port timing, etc.)  It's also possible to make your engine such that it would detonate under normal circumstances, but the octane of the fuel makes detonation more difficult, or the combustion chamber was forged by a white-bearded Wizard so it doesn't tend toward detonation, or something.  There is a lot of power to be had without making the engine unsustainable, although engine lifespan is a very dynamic thing that's surely affected in some way by just about anything.

Again, that's something for the Project Two-50 guys, they know much more about wringing power out of a 250 than I do.  All I can do is regurgitate stuff from Gordon Jennings.  I believe I heard someone (was it John?) say that the P250 bike was in 55+ horse territory, which much more work done than a simple silencer!  If it was that easy to get 55, I'd expect our boys to be running a bike with the power of a Slant-Six after all they've done.

[TMKIWI]

I'm just curious how much the average 250 2 Stroke makes in Horsepower and in Torque, compared to the big 450F thumpers? 

Modern 250's put out about 28-29ft/lbs of torque standard.
A 450 is around 33-34ft/lbs standard.
Give or take a little for the different brands.

[maicoman009]

One thing that we do know is 250 two strokes when tuned & set up properly can exceed 50+ horsepower. A good engine tuner can pretty easily get to 50 HP without too much stress on the engine.When a 250 two-stroke is tuned to put out 50 HP it simply must get the proper & scheduled maintenance....

[JETZcorp]

And at least a 200:1 oil ratio!

[opfermanmotors]

Also, A buddy of mine who rides an 06 RM250 came over tonight and we were talking about how much power my YZ250 most likely made. I guessed anywhere around 44-46HP. He said thats too low and that his RM is makin like 55HP!! I immediately called Bull$hit. and he said with his exhaust setup "its a stock pipe with Pro Circuit shorty

It might be true, what color are his hand grips?  If he got aftermarket SCOTT hand grips in black I can see it pushing 55 hp.  If he would have gotten the red ones though, most likely would have hit 60hp.

[JETZcorp]

Yes, that's true.  Considering Suzuki is a Japanese company, it should follow roughly the same rules for power as the other Japanese makes.  Check out this master at work.  That's an extra 314 horses up in this, yo!

[eprovenzano]

[quote author=opfermanmotors
It might be true, what color are his hand grips?  If he got aftermarket SCOTT hand grips in black I can see it pushing 55 hp.  If he would have gotten the red ones though, most likely would have hit 60hp.
[/quote]

That's it, I'm changing my grips, as I have gray ones which we all know de-tunes the bike.  

[JETZcorp]

No, what you really gotta do is add stickers.  That way, when you go by someone, they'll think you're sponsored.  Start with the basics, Rockstar, Monster Energy, and whoever makes the oil you happen to be running at this moment in time.  When you're done with that, move up to the more advanced stuff.  Go to Google and search some shops that specialize in every part of a bike, and go to the 52nd page, pick a random one, and put their logo on their bike.  If no one's heard of it, that means they're exclusive and you got da hot shit.  Do that for everything on your bike, top end, cooling, transmission, clutch, and plastics.  Keep coming up with ideas for companies you like or that at least have a vaguely interesting logo, until your bike's color is no longer discernible.  Then, and only then, will you have a bike that people will drool over.  Remember, each sticker is +0.5 horsepower, so aim for many small ones rather than a few large ones.

Works every time, trust me.

[msmola2002]

Yes, that's true.  Considering Suzuki is a Japanese company, it should follow roughly the same rules for power as the other Japanese makes.  Check out this master at work.  That's an extra 314 horses up in this, yo!

looks like he has been getting his modification ideas from here
http://www.angelfire.com/nc2/mycoffeecan/page1.html

[Turquine]

[Paul P]

Trying the 03 model of John Dowd's was a treat. I sure would like to try the 2010 model. JD's had the Boyesen Rad Valve, an FMF pipe, and the suspension was set up for him. It fit me very well, I was told I looked good on it, even for an old man.
   I had a CR250 there that day and it did not have the smooth punch his KTM had. The CR was not as fast anywhere, and handling was stable. The KX's feel very mellow compared to my CR, the YZ's have a nice motor, but they feel like the shifting is still notchy even after all these years.
     Quality is very good on the KTM's, and that's one reason they are so popular in off-road events. Off-road events are much harder on equipment than motocross, as the offroad events are usually a couple hours long, unless it's an enduro 6 day, then it's worse. I have bought a few used enduro bikes cheap, but everything is usually trashed on them from the ground up.
   

[2T Institute]

A 250cc MX engine converted for use in shifter karts have about 70-75HP that being the limit. In MX what matters most is the shape of the curve, where peak torque is and how long it hold peak torque for.
But a stock RM isn't going to make 55HP.