how much power?

[vtfootball79]

i just bought a 2002 wr 426 f and was wondering how much horespower it has? my friend told me that new 250's have about 60, and i've seen posts where they say the 426 has about 40, but i know my bike is a lot more powerful than any of the 250's i've seen or ridden. could this just be becaues it has more torque?

[StreetMoto]

250 2 strokes have around 45-50HP...

426's rip it up but I dont know how many HP they put out....

congrates on your new moto!!

[dominator426]

I have seen 51.8 horsepower I think for the WR426 from a reputable source...trying to remember where...

[SFO]

Here are two dynojet runs.

One is a stock yz-f 426 the other a 97mm 444cc Wr I built with the help of my friends.

http://209.197.247.209/Dyno_runs/baseline_yzf_+444.htm

[blue_beast_wins]

I think you will find that the horse power has been mesured from two very different places, one from the flywheel and one from the rear wheel, standard wr426 has about 42 at the back wheel, same as a KTM 300.

[ June 10, 2002: Message edited by: blue beast wins ]

[vtfootball79]

thanx for the help, this bike does rip i t up, it's gonna take me a few more rides to get used to the power, it's a big jump from my slowzuki four wheeler

[XR6's_rule]

Exactly right. The manufacturers may rant and rave how their new "rocket" produces 55 hp, but most of the time there is a bit of lying in it and the HP ratings are always measured from the crankshaft. Now we all know that motorcycles don't go that well without sprockets, chains & rear wheels-the only HP ratings to go by are the ones measured at the rear wheel aka-a dyno reading. A classic example is when Honda released the CRF450 they claimed it to produce an amazing 55 hp. This is of course poppycock as numerous dyno-runs have them pumping out "only" around the 46 mark. Nevertheless, this sort of output puts it into XR650 territory! ?

So the moral of the tale is to never read too much into the manufacturer's claimed HP outputs.

[weekendtoy98DR]

Yea and you can add "claimed" weights to that folder as well.

[Racer4]

Are there any places I can find dyno sheets on 2002 YZ 426f with a Stage 1 kit..I race a Micro Midget race car with this engine and am trying to match the gearing to the engine. I use Micron 4 plus a data recorder which helps tremendously to 'find' the thing...any help on  max torque\rpm is what I am looking for along with HP curves...Also am parting out a 2002 bike that the engine came with...

[grayracer513]

Actual facts are, just for starters, that the current crop of 250 two-stroke MX bikes averages about 43-47 hp, while 250F's are pushing 37-41. None of them are anywhere near 60.  The '15 YZ450F is in the stratosphere by itself at 57-59, depending on the dyno, the day, etc.  Most MX450's are right at 50 (49-52).  Late model WR450's (pre-EFI) came in at around 37.   This is rear wheel measured, not imaginary "at the crank" stuff.

 

The YZ426 typically posted numbers in the 46-47 hp range.  Figure the WR426 to be 6-8 hp less than that. 

[cubera]

Here's a thread about WR HP/ Dyno results.

 

https://www.thumpertalk.com/topic/252937-dyno-numbers-wr450f-anyone/

 

The 2013 derestricted and tuned WR pulls hard and long. I have not one complaint about the motor. Whatever it would do on a dyno for RWHP I don't know for sure. It's running strong at over 125 hours and has been reliable as an anvil. ??

 

Sorry I'm of topic a  little

Edited November 20, 2014 by cubera

[YamaLink]

A 12 year old thread resurrection. Impressive!