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Dyno Tuning, part deux


sredish

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Sup fellas, I talked to a dude that has a big portable Dynojet made for cars/trucks. He says he's ran a couple quads and motorcycles on it. He told me $20 for 5 or 6 runs. I thought I'd ask a few, more basic, questions.

 

How should the dyno run be performed, in regards to what gear(s) to use and other misc. things to do? Should I ask him about when it's been calibrated or anything to help insure the accuracy?

 

He said a stock 400ex he ran on it was just barely wide enough, but fit and put out like 25 hp or something like that. Does that sound right? He also said he had a decently modified YZ250 on it and it ran like 32 or 33 hp. You guys think that's fairly accurate?

 

I guess my concern is putting a quad on a big wide machine for cars/trucks and not getting accurate readings with the little amount of power they put out. I'm also gonna run my truck and see what she puts out, I'm hoping for 750 lb. ft. of torque... :rolleyes:

 

Grassyass!

Edited by sredish
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the dyno I used before the shop got shut down by the irs was designed for cars, he just bought the program for small engines. But the drum was to little ones, but i was just wide enough to get good runs down. But the numbers he's telling you sound really low.......a bone stock yz250 has almost 40 and a stock yz450f dirtbike has 51 rwhp. Hell for $20 bones I'd run the shit outta it. YO!

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But the numbers he's telling you sound really low.......a bone stock yz250 has almost 40 and a stock yz450f dirtbike has 51 rwhp.  Hell for $20 bones I'd run the shit outta it. YO!

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I'm GONNA run the shit out of it for $20. But I also felt the numbers were a little low. I'd hate to run some small number and be pissed, but since those are low, I'll at least know what to expect. Guess it'll at least help me get it dialed in good, I can at least watch the curves.

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even if the numbers were low,as long as the dyno in consistant its still a solid baseline to tune your shee on it.its nice to see actual numbers to say if this adjustment made a difference.BTW those H.P. numbers that tats said were they at the fly wheel HP or real wheel HP?youll be suprised how much hp is lost through the drive train.

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Yea, chicken, that's my thoughts exactly.

 

What about gear? What gear do you all typically run it to, or just run it all the way through 6th and rev that bitch out, I guess that sounds like what you all have done from reading back to your other posts on this.

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What gearing you run the bike in is up to the operator. A motor will make more power on the dyno when its given a load. A good example of adding a load to a bike is by dynoing it in a high gear. 5th is most typical. Dynoing in 6th can be too much of a load and kill the hp.

 

Those numbers dont sound too low. Although dyno jet does not recommend mobile dyno's because its a very sensitive peice of machinery. They say unless calibrated often it wont be accurate or consistant.

 

On my dyno a stocky yfz dyno's at 38hp which is consistant with 5 other shops around california and arizona. Not sure if a dirtbike 450 would come close to 51 on any of our dynos

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i have know idea on witch gear to run.ive never dyno'ed a bike just cars.i usualy run cars :manual trans: in third gear.it gives the engine a longer pull to the red line. i would think 4 gear would be a solid gear to try it out but ive seen guys on tv run them straight though all the gears,bouncing off the rev limiter on each.

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