yz 250

A fella in the thread below this one rode his yz250 and was pretty impressed with it. I would love to try a 2 stroke with a kit. I normally pee premix anyway.
The attraction to 4t thumpers is the broad powerband, fuel economy with possible fuel injection and e-start.
Most of the bigger bikes are in the 45 to 55 hp range, which seems to me like it allows a trackspeed that is just below a level that would really lets these bikes get up on top of the snow and just fly. But until they can achieve about 80hp we will be tractoring around and still having more fun than we had on our sleds.

Try it with a kit, you wont regret it.

yep they work pretty good, I rode with a guy on here cwooster that had one with a 136 track and he walked all over my 121 wr450, his only complaint was the skinny powerband, you just always had to be on it.

yep they work pretty good, I rode with a guy on here cwooster that had one with a 136 track and he walked all over my 121 wr450, his only complaint was the skinny powerband, you just always had to be on it.

I ride an '06 YZ250 and really like it. Have not had it in "deep" powder yet so no comment in that department.
The motor is stock (but tired) with a Pro-Circuit pipe. As best I can tell from surfing around the internet it would be around 47 hp with fresh top end. Since it's getting a new piston this summer, I may put in a 295 kit (the same cost as a fuel controller for a FI 450, approx $600). This will fatten the power band and make it easier to chug around like a 450.

I ride with some KX450's and they do go better, but for me the fun factor of a two stroke is where it's at. If you are getting into snow bikes for maximum hp and hill climbing, you would be missing the point altogether. That's what my 280 hp Nytro is for.

http://www.eric-gorr.com/bigbore250.html

Some dyno info I found:

http://antithumper.700hp.com/gasserfly.html

Dyno Test Results
2007 Honda CRF 450R: 51.2HP@9,540 RPM. It has FMF pipe & Stage II cam.
2006 Yamaha YZ250: 47.5HP@8,530 RPM. It has a Bill's Pipe.
2001 KTM 380SX: 51HP@8,050 RPM. Tired engine. (55HP fresh?)
2000 Honda CR500: 58HP@6,400 RPM. Pro Circuit pipe & Boyesen reeds.
2008 Gas Gas EC300: 47.6HP@7,300 RPM. Bone stock. Bel-Ray MC1
-----------------------

YZ250F 36 HP@11,000 rpm, 20.1 ft-lbs torque
YZ250 46.4 HP@8,500 rpm, 30.6 ft-lbs torque
YZ450 54 HP@?? rpm, 34 ft-lbs torque

From MXA Magazine:

Q: HOW DOES THE 2011 YZ450F RUN ON THE DYNO?

A: Maximum horsepower was 53.88 ponies. That’s a healthy number, albeit less than what the KTM, Suzuki and Kawasaki make. Maximum torque was 33.95 foot-pounds. For comparison purposes, the 2011 CRF450 (34.36), RM-Z450 (34.77), KTM 450SXF (35.28) and KX450F (35.29) all produce more torque. The YZ450F did, however, beat the KTM 350SXF (33.95 foot-pounds to 27.34 foot-pounds).
-----------------------------
Q: HOW DOES IT RUN ON THE DYNO?

A: It (2012 KX450F) makes 55.50 horsepower at peak (the 2011 KX450F made 54.17). Best of all, it crested the 50-horsepower mark at 7400 rpm and stayed above that mark all the way to 10,200 rpm. That is an awesome spread of power. It makes more horsepower than the 2011 KX450F engine from 6200 rpm all the way to sign-off, but doesn’t really whip the 2011 KX450F bad until 8500 rpm—and by 9500 it is making three horsepower more.
http://motocrossactionmag.com/Main/News/MXAS-2012-KAWASAKI-KX450F-MOTOCROSS-TEST-AN-ENGINE-8331.aspx



Sorry for writing a book, guess I'm bored and it's raining outside today.
Cheers!

LG

I've heard that the big CR500's are pretty sweet on the snow.... I'd love to see one in action. The draw to the KX450 was mostly due to EFI and the HP the KX puts out. I think 2 stroke would be more "fun", but for me having the kick-and-go and no fuss of the EFI is a major plus.

I rode Beau's demo carburetted KX450 for an entire day this winter. That thing did not miss a single beat all day. I even tipped it over several times (happens when you are new and stop in soft snow). Started right up within two kicks. "Kick" started it with my hand four or five times, it starts that easy. I can only imagine that the fuelies are that much better (and of course the power increase). Very nice bikes for sure.
If only I were independently wealthy...... LOL

get a cr500 and never have to look for more power. With that said I dont have a 2moto kit but ride both a yz250 and a cr500, I like both but there is no question which one is faster in a straight line. And they don't bog down and need to be held WOT all the time, the torque is great.

What about kx500. building alu. Frame kx500 big bore for a guy for next year. He rides kx511 big bore wow 2strokes are fun light and fast.

I was going to use a KTM 300 I think they make around 50 hp with less weight ,,but I love that bike in the summer so I decided to go with the 4stk to save my summer ride any pain ,,,,Seems funny to me that we can feel the 1.2 hp difference between the KX and the YZ I guess I need cams and a head port job so I can get to 56 woohooLOL,,let seee that gota be $3k:face-icon-small-tonI see in the yamaha acessories they sell exactly those parts,hummmmm!!,

Snocattin's YZ250 ripped last spring. A 250 two stroke puts out about the same HP as a 450F, and is 30lbs lighter. Excelent boondocker. Also, a two stroke with a "bang" every stroke, produces more torque than a four stroke. The CR and KX 500's that Service Powersports tested produce double the torque as our 450F bikes! Carburated two strokes jetted correctly run flawlessly. I would not be concerned about that at all. You have seen some of the Timbersled company vid's by a pro rider of theirs. His bike is carburated and jetted spot-on. One advantage is the ease of changing AFR's with a carb. Ten minutes and the combinations are endless. With an EFI you need a tuner, I recommend the Bazzaz ZFI-MX, then the spot-on AFR's are easy. Lots of fun and exciting things to experiment with!

Here's some fresh dyno numbers from my 2012 KTM500 EXC
Unfortunately doesn't my bike have any revcounter so the figures in the bottom show the power in relation to rear wheel speed in km/h.
Peak power is 55,6 hp

swedenturbo said:

Here's some fresh dyno numbers from my 2012 KTM500 EXC
Unfortunately doesn't my bike have any revcounter so the figures in the bottom show the power in relation to rear wheel speed in km/h.
Peak power is 55,6 hp

Click to expand...

I ride with a guy that has a 12' 500 and it's pretty impressive especially in the heavy snow. My CR500 will out pull him in the powder but the heavier the snow gets the more trouble I have maintaining rpm/peak hp and the 4strk 500 puts me to shame. There are some real advantages to both breeds probably more for the 4strk but I will stick with the 2strk for now.

Good to hear,, because my 570 berg drives away easily from the 500's

swedenturbo said:

Here's some fresh dyno numbers from my 2012 KTM500 EXC
Unfortunately doesn't my bike have any revcounter so the figures in the bottom show the power in relation to rear wheel speed in km/h.
Peak power is 55,6 hp

Click to expand...

Is that with an unlocked ECU?????55.6hp thats the same as the 450SX factory edition?

It was bone stock, right out the box.

I got rid of the emission stuff and added a jd jetting tuner and it really helps the 500. In stock form it is too lean to meet emissions. Are you going to keep your 500 stock?

I hear that the unlocked ECU makes over 60 hp ,being your in europe I would think it should be easier to get the factory to send you the unlock code to get your ecu to do the big HP thing dealers here are having a hard time getting them to send the info,but I hear the supermotard racers are getting the right stuff, for some reason the bergs are also getting the hot maps sent to us easier!