Well guys I have some very bad news...

[miedosoracing]

Yesterday I went riding my CR144 E85 Eric Gorr.  There was a KX250F 2011 there.  On the track we were pretty close, following eachother. I haven't ridden since March though, and so if I practiced I'd clearly be faster. Anyhoo We got chatting, and I said I'm pretty sure this bike will beat that in an all out drag race, because it's not a 125 any more.  He said, let's go race, I was cool with that. We went up to a road and went at it twice. Both times, we were dead even from start until I topped out, and let off.  His bike clearly still had more to go as he started pulling at the end.  So my conclusion, and even my friend who was with me that is a 4 stroke fighter through and through, that it is more fair than many think with 250 2 stroke vs 250 4 stroke.  Being that 4 strokes have smoother power, the 144cc just isn't any faster than the 250F.  It is just as fast, but the fact that a 250F has smoother power, If I was racing, I would want a 250 2 stroke against a 250F, not just the 144.  I left pretty surpised, but also now understand why I keep seeing videos with 250 vs 250 being very good races.  That bike was still stock as well, although pretty loud, so may be opened up. Anyways, Just my person opinion...

[VintageBlueSmoke]

Have you changed the sprocket(s) to match your enhanced engine? You have to consider gearing also.

I hate to bring up old stuff but in 2001, the Yamaha YZ125 had a higher top speed than a KTM 200... Of course the KTM had more power and was faster out of the corners but at the very top (not a drag race but max speed), it was all YZ.

Putting the 139 kit on the YZ made it faster in the corners AND on top.

That is apples to apples. When you compare apples to pears (2T vs 4$), you have to take ito account the better application of power advantage of the 4$ but I would guess a 144 should be able to take it in max speed with improved gearing.

Inaddition, power isn't the advantage that the 2T brings to the table. WEIGHT is (both "feel" and on the scales). You can take two identical weighted motorcycles and the 2T will always "feel" lighter due to it's lower CoG and less rotating mass.

[eprovenzano]

I have to agree, the drag race results while somewhat surprising, is only one piece of the puzzle...  Do you feel on the track, if you were in racing shape, as though you'd come out on top?

Let's take that one step further...  If the two of you have equal talent and equal fitness, do you feel your smoker would win on the track?

[SachsGS]

Put them both on pavement and I'm pretty sure you will see different results.

[burn1986]

Whew, that's a relief! I thought something really bad had happened.

You're still looking at a high performance 4-stroke that is still almost twice the displacement. And it has a larger power spread, and more torque. I'm not surprised that it won out. The power spread of a 250 s-stroke compared to a 250F is way more even. Even though the 2-stroke makes more peak power, the 250F makes up for it with power spread, making them virtually equal.

[rookie]

it is the singer...

[juliend]

Whew, that's a relief! I thought something really bad had happened.

You're still looking at a high performance 4-stroke that is still almost twice the displacement. And it has a larger power spread, and more torque. I'm not surprised that it won out. The power spread of a 250 s-stroke compared to a 250F is way more even. Even though the 2-stroke makes more peak power, the 250F makes up for it with power spread, making them virtually equal.

This.....

[miedosoracing]

Welp, I figured you guys would have those responses    The good news, is hp wise, I'm pretty sure it was dead even. So anyone know the hp for a 2011 KX250F?  Second, yes it was on pavement.  The thing is, here is why my opinion stands. Like Burn said  If we wanna compare, the 250F has smoother broader power.  So although these two seem to be equal, you gotta compare the whole track. So the question was asked, if the same rider was on both bikes, who would win.  If the rider never ever made a mistake, the 250F would out perform the 144, just on the mere fact that it has an easier time doing certain corners and jumps.  Then, add in the fact that no one, ever does a complete moto, without atleast a small mistake.  I feel the 2 stroke cc vs 4 stroke cc is a fair fight.  Again, it's my opinion, but I just think the 250 vs 250 is fair.  

Something else to keep in mind here guys. My bike is about as maxed as I can go. Gorr porting and cylinder/head mods. Cases ported and matched. So my point is, the 250F as stock has a lot of potential still too, as we know Pro Circuit gets about 10 more hp. 

[streaks383]

Weight to power ratio makes a huge difference.  Where you two the same weight?  Was one persons tank full and the other half or less.  When we talk small amounts of HP and Torque a few pounds makes a difference. 

[miedosoracing]

Like I had stated, it's really a null point about weight etc.  Amateurs already have the cc vs cc, so this post was regarding the Pro rules that Burn is trying to get passed.  No Pro has a stock 250F, so add 10 hp to a 250F and the close race I had, no longer...

[VintageBlueSmoke]

OK, I have to give in. A 144 2T in most capable hands is still no match for a modified 250 4$ in equal hands. On the right track, terrain or the given the right circumstances, the 144 might find an edge. However both are relative hand grenades with the pins pulled. I'd take the 144 for longevity though.

I also think the 144 would be better in the Vet Pro class (though probably not the Senior classes). The vets would know how to take advantage of the smaller lighter bike.

Finally, if you were to run a sub-150cc in something like the Monster Cup (or whatever it was called) where the production rule book was thrown out the window, I would think you would be able to produce an sub 150 pound 150cc 2T and really scare the big thumpers!

[GlennC]

Whew, that's a relief! I thought something really bad had happened.

You're still looking at a high performance 4-stroke that is still almost twice the displacement. And it has a larger power spread, and more torque. I'm not surprised that it won out. The power spread of a 250 s-stroke compared to a 250F is way more even. Even though the 2-stroke makes more peak power, the 250F makes up for it with power spread, making them virtually equal.

This.....

X 2

Equal displacement is the only way 2 strokes will be relevant.

[rbigair40]

No way a THUMPER can out run a 2 stroke no way man no way !

[snook620]

Dammit bigair you just made me spit coke everywere 

I would LOVE to have seen this race....

[miedosoracing]

No way a THUMPER can out run a 2 stroke no way man no way !

Says the guy who rides a 250 2 stroke now, in replacement for his 250F. LOL.      Yeah, I guess the 105cc's does make a difference.  I too can kick Tiger Woods azz with a 105 stroke handicap. Ha ha.  Means, I'm better than him.