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WR250F Captain

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  1. You CANNOT directly measure torque from an internal combustion engine. It must be calculated after directly measuring power output (HP, KW, PS, not newton meter or ft lbs) Torque is a static force devoid of time (moving a pound a foot, not a pound a foot a second, hp is how many pound you moved in a given time (hp=(rotations per minute X pounds a foot)/5252)). As long as the motor is spinning, time is included as torque is being applied by rpm yielding power, and the higher the rpm (given torque is constant) the more energy the dyno will detect. Dynos measure power output, whether by magnetic fields or other forms, and calculate torque by removing time from the equation (ie. Measured 10hp at 2,626 rpm would equate to 20 ft lbs). You can measure torque with an electric motor, as the motor doesn't require spinning to generate power (doesn't need to intake air, and compress the air and fuel in order to generate power). If you remove the rpm lead from any dyno it will simply tell you power over speed.
  2. What a load of... Unicam valves. Horsepower, believe it or not, is the measure of WORK and POWER. It is force over time. Torque is a STATIC force that has no time. Two identical vehicles with identical forces acting upon them, the one with the higher average HP, not torque, output will accelerate faster. Torque is not tied to acceleration. You can have 1 million foot pounds of torque and be able to produce less power than an engine with 1 foot pound in theory. 1 million ft lbs at one revolution a year (525,600 minutes) is .00036 hp (HP=((1/525600)(1000000)/5252)), while 1 ft lbs at 5252 rpm produces 1hp. If you do the math, the y2k bike makes (420hp @ 52,000 rpm per MTT) 42 ft lbs of torque at peak power. Are you going to say that 42 ft lbs is weak or slow? No, because it was one of the fastest production vehicles during its time. You're correct in stating peak hp doesn't correlate to overall acceleration, it correlated with the acceleration at that particular rpm, but it is the average horsepower throughout acceleration that determines your velocity (while taking outside influences into account, such as wind resistance, frictional coefficients, weight, grade, etc...) average torque doesn't. You can have an engine produce more torque over a broader spectrum, in a vacuum per se, and still be slower, but you can't have the engine that produces more hp over a broader rpm spectrum be slower (given the gearing keeps each motor in their "broad" rpm band). The european measurement makes more sense, kw, as it directly states an energy output. Horespower is causally linked with energy, but is a confusing translation.
  3. WR250F Captain

    Still having bogging problems when gassed!

    ^^^ what he said and if that isn't detailed enough, it helps squirt the fuel in quicker... when you get better with tuning, you can try different diaphragms. on my old ktm, I ran the honda one and it did wonders... pumper tuning is huge for me, but I like to wheelie over stuff
  4. WR250F Captain

    Still having bogging problems when gassed!

    you shouldn't be riding at idle anyways... when you goose the throttle off idle it's the worst bog you will see. if you have bad bog when riding it will ran bad for a second and clean up and accelerate. getting that throttle response back is what you should be tuning for, not idle. when I had a 250, 450, 600, 1000 I went from engine braking to WOT a lot. more so on the lower cc bikes. if you have the accelerator pump tuned correctly, you should be able to brake into a turn, get out of the turn and go WOT without any hesitation. if your stuck having to slowly add throttle that just sucks and is no fun, ive been on bikes like that and when I nail the throttle it bogs so bad I hit the bars then it takes off... no no no.
  5. WR250F Captain

    Still having bogging problems when gassed!

    your pumper should squirt fuel when you crack the throttle open suddonly... it's a finicky part of a carb and requires a lot of tuning to get right wr's come with bad jetting for better emissions and what not. non race dirt bikes usually come with vacuum operated slides that don't open fast so this doesn't happen
  6. WR250F Captain

    08+ mask + hid = scatter?

    HID's make light in a different way. halogens are brightest in the middle of the filament and reflector housings are made to work with that HID's are the most dim between the electrodes and brightest on the outside, the opposite of a halogen this is why light scatters, it's in a different spot in relation to the reflector and bounce off at a different angle. you need a housing designed for HID's, so yeah, go with the x2 hid you can always retrofit bi-xenon projectors if there is enough room, i did it on my gsxr1000 and my 98 dodge ram, they work awesome and only blind people on command
  7. WR250F Captain

    '08 450 excr main air jet?

    excr has broader power and more top end power over a free modded wr450, friend had one and we always swapped. the wr's suspension was a lot better though. if your looking for snappy ness, you'll probably want to tune to pumper, you do that by putting in different leak jets (which allow fuel to flow away from the pumper circuit) different diaphragm or tighten the linkage. I put a Honda CRF450R diaphragm in and it mad a good difference in snappy ness I tell you what... bobby.... ooohhhhoooww -hank hill the main is for top end fueling and it works in conjunction with the needle for low and mid range fueling and the needles taper is what determines the progressiveness of it, and the pilot is idle i'd try the honda diaphragm and o ring the linkage, that should help make your motor have better on/off throttle response
  8. WR250F Captain

    WR250F 2004 More Power

    my perception of them was no lose in low end torque and good gain in top end... if it did lose bottom end, only a bit, as the bike was easy to wheelie and i don't wheelie bikes at high rpm unless it's a 2 smoke
  9. WR250F Captain

    Xc-w 2009 - 2010 - 2011

    even though I put 5000 trouble free miles (somewhat, i'll explain) before I sold it. the first 50 miles I lost all engine oil, went into tranny, took it to dealer and they charged me said it was my fault, then it did it again and took it back. had to call KTM like 5 times before the guy actually talked to head guy at dealership and said they would cover it, called it "overfilled transmission fluid". and they had if for over a week to change the oil... never did it again after that. and was a great bike when it didn't try and kill me 08 exc-r street legal
  10. WR250F Captain

    '08 450 excr main air jet?

    main air jet? when I installed a jet kit on mine, I had to put in a new main jet (not sure if it's what your talking about though)
  11. WR250F Captain

    450 exc MPG

    45mpg cruising speed limit with offroad gearing (forget what it was). got better mpg on my k9 gsx-r1000 though.
  12. WR250F Captain

    WR250F 2004 More Power

    I ran stage 2's, they made a huge difference. loved the top end it gave it. mega bomb also made a nice increase throughout the rpm range, which is nice but pricey
  13. you can't on the exhaust because the auto decompression, but on older wr's and yz's, pre decomp, you can do that. I had a sheet from a gytr kit that said to do it on a wr to make it have yz timing. if you want more low end, I think you can just either find a wr exhaust cam or buy some hotcams. I went with hotcams and they made a nice difference in top end and didn't notice anything else lower, mostly cause I never used that much power with lower revs anyways.
  14. on my 06, it made a huge improvement. it works from midrange to the top. my bike went from twist and go, to twist and hold on because the back wheel went every which direction. good mod, you can even hook it up to a switch. but your bike has to be shut off to switch maps
  15. WR250F Captain

    Best big bore 269cc or 300cc?

    I'd agree with you on that and add this. more torque will give you better accel, because the power isn't coming on as sudden the tire will be less likely to break traction. 450's have much larger tires and have more traction, plus less rev happy motors means they don't always want to break traction as easily. my 250f had more wheel spin than my 450f, my 450 would just wheelie. see, this is because all you did was change your displacement and jetting. the stock cams aren't going to make power for this displacement. if you were to get custom cams, or different ones, you can shift your power up high, or down low. plus a good rider can feel when your starting to lose power and shift. a good bike won't make power all the way to redline because they you won't have overrev and if you hit the limiter on accident you can lose all forward momentum
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