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RC81

04 WR450 37hp after mods? Sounds wrong.

21 posts in this topic

In this months Dirt Rider they did all the mods then got 37 hp. on the dyno. Sounds low to me, a DRZ400E puts out at least that if not more. Whats wrong?

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who cares what #s who ever got from some sketchy dyno. ride a moded drz back to back with a moded wr450......i have :)

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Thats what I was thinking, theres so much variation on dyno numbers so who knows...

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Dyno's have different ratings for horsepower. There is no real standard for rating horsepower so a Dynojet Dyno will read higher than an Eddy Current Dyno. There may be other dynos but I am not familiar with them. I would say the Eddy dyno is better since it tests under a load and you can measure each rpm range and torque better . What really matters is the difference between your starting point and finishing point. If the mods gave you 5 horsepower then it is helping. A friend of mine works with the Eddy dyno and the YZ 450makes about 45 hp and the WR 450 about 40 hp with a pipe and mods.

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I thought a stock wr450 was about 43 to 45, and 47 to 49 after mods. :)

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In this months Dirt Rider they did all the mods then got 37 hp. on the dyno. Sounds low to me, a DRZ400E puts out at least that if not more. Whats wrong?

What's wrong is you're too focused on the peak numbers and not on the increase. The dyno runs were done with a stock tire, which is not ideal for an absolutely accurate peak HP rating. The knobby slips somewhat on the dyno drum and this slippage results in about a 20-25% error in calculating peak values. Fortunately, all other things being the same, the increases noted are relatively accurate from stock to modified. That's what was important, not the peak HP rating.

In the same issue we tested a number of pipe sets on a Honda and a Suzuki. For those tests it was worth the extra effort to replace the knobbies with a street tire to limit dyno slippage since peak HP was important to comparing one pipe to another.

If all you do is look at the peak number rather than all the information provided, you are likely to be disappointed with your choices. Weighing all the information and applying it to your own type and style of riding will result in greater satisfaction. Peak HP numbers are usually only good for bragging rights.

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Thanks for the clarification. Do you know how much hp the mods added? I didn't see the starting point or did you just dyno it after the mods since they are pretty much a must do? Again, thanks for taking the time to answer my question.

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I read it yesterday, pretty sure it said 47 HP.

No it was 37. Thats what had me wondering.

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the way my 04 450 just spit me off- I would have sworn 147 HP !!! Seriously I would have thought 47 was more in line also. Since this is my 1st off road bike, I was amazed at how large a difference the grey wire, air box, and pulling the baffle made. Spending the past 25+ years riding on the road, It costs a ton of money to really get any jump in power or any major improvement on a road bike. I really do not care about the inal numbers with my WR- with all of the cheap mods- the bike is so much better and fun to ride- besides, being 45, and just learning the off road game (sometimes the hard way :) ) I love the way the WR feels and rides. :)

The best part of crashing is while you are healing, the new parts take time to come in, and by time you get them on, you are all heled upand ready to ride

If your toys can't kill you- you need to sell them :D

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Rick, whatever you guys are doing, keep it up. Dirt Rider has gotten better and better over the past few months. I even re-subscribed.

I used the money that I usually spend on DIRT BIKE to pay for it.

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Just goy my issue of Dirt Bike and it had a test for enduro 450 with estarts, ie the Honda CRF450X, Yamaha WR450F, KTM 450 EXC, Husky TE450 and the Yammie did the best (with grey wire cut, throttle stop removed, snorkel mod done) and it did 44.96 HP, in fact, it was more than all the other bikes in the test. Next in line was the Husky at 44.50 or so, then the others were all around 42 and a little change.

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I gotta get me that issue, I thought something was up when I seen 37hp also.

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Thanks for the clarification. Do you know how much hp the mods added? I didn't see the starting point or did you just dyno it after the mods since they are pretty much a must do? Again, thanks for taking the time to answer my question.

I left out the base HP because it wasn't what I was trying to show. So many readers get wrapped up in peak HP numbers that they ignore the increase in throttle response and overall power, which are more important to rideability than some meaningless number. For most of us, a boost in low-end torque has significantly more appeal than a few extra HP at or near red line. The mods covered in the article make the WR rev faster and pull better throughout the RPM range. All together, the mods were good for about a 10% increase in HP and about 8% in torque. There are very few single aftermarket parts you can buy that will give you that much increase by itself. This has more to do with how stifled the WR is from the factory, but as I said in the article, most bikes have the potential already built in, you just need a little effort to unlock it. If you look at the pipe test article (which I also did the dyno tests for) you'll see the race-oriented Honda and Suzuki showed a much smaller increase from aftermarket pipes. Race bikes that aren't restricted by a need to meet any regulations are closer to their potential than a trail bike like the WR, but there's always room for improvement on any bike. Mass production introduces certain compromises that often don't lend themselves to peak performance. If that wasn't true there would be little need for aftermarket parts. Obviously, we are lucky to have such a healthy aftermarket to help us squeeze every last bit of performance from our bikes. The big difference between a trail bike and a race bike is the trail bike will benefit more from simple, easy, and cheap mods, whereas the race bike is already so close to its potential that expensive mods are often needed to take it to the next level. The WR is a perfect example of this. I think I invested less than $60 in the mods I covered, yet the difference in rideability was like night and day. It would be nice if the bike came from the factory not needing any mods, but I would have been very disappointed if I found that the WR needed expensive modifications to make it run like it does right now.

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Rick, whatever you guys are doing, keep it up. Dirt Rider has gotten better and better over the past few months. I even re-subscribed.

I used the money that I usually spend on DIRT BIKE to pay for it.

We have Jimmy Lewis to thank for that. Besides being a racer, he is a gearhead who loves the technical side of things. He is as passionate about motorcycles as anyone I've ever seen. :)

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Just goy my issue of Dirt Bike and it had a test for enduro 450 with estarts, ie the Honda CRF450X, Yamaha WR450F, KTM 450 EXC, Husky TE450 and the Yammie did the best (with grey wire cut, throttle stop removed, snorkel mod done) and it did 44.96 HP.

I don't know how Dirt Bike does their dyno testing, but as I said previously, with the stock knobby on the dyno there is about a 20% reduction in output due to wheel slippage. Accounting for that, my numbers would be right in line with Dirt Bike's, assuming their testing was done with a street tire or corrected for the error. At 44.9 HP after the mods the WR is close to the numbers of the stock CRF450R I dynoed for the pipe tests. Not bad for a "trail bike." :)

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Was the CR also dynoed with a knobby on it?

Just looked at your home page, might have some future questions for a fellow 350x owner and rider. :D

Whats wierd is that you guys ended up having the same jetting on that wr450, as I do on my 01 426 :)

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I also read 37 horsepower , who cares what the number is as long as the bike is fast.

Well, you'd really like the CRF250 bike they had in there with a big bore kit. I think it was something like 307cc. It cranked out 45 HP, now that would be a nice fun light bike to flick around in the trails. I rode a buddies CRF250 and really liked it. I've always had a soft spot for the CRF Hondas, ie 250 and the 450!

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Was the CR also dynoed with a knobby on it?

Just looked at your home page, might have some future questions for a fellow 350x owner and rider. :D

Whats wierd is that you guys ended up having the same jetting on that wr450, as I do on my 01 426 :)

The CRF and RMZ were both dynoed with a street tire (dirt tracker, actually) inflated to 32 psi. Since there were so many dyno runs involved it was worth the extra effort. Also, the pipe test was a comparison between brands, the WR test was just a validation of an increase.

I'm a rare bird in that I still love my ATC. Most dirt bikers hate ATV riders, but I like everything with wheels and a motor. The 350X is basically just a sand toy now, but all my ATV buddies are on quads. I hate riding quads. Too big, too heavy and nothing like a motorcycle. The ATC still feels like a bike.

Why would the jetting surprise you? The 23cc difference is not enough to make a substantial need for different jetting. Since I wrote the article I have switched to an FMF Ti4 exhaust and had to raise the needle one clip position. :)

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