Dyno
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Tourer
Joined: Mar 2007
Posts: 368
Likes: 2
From: Salina, KS
Dyno
Last winter I did a conversion from a Stage 1 1200 to a 1250, had the heads ported, polished, installed SE 536 Cams, added a Mikuni carb and 2-1 pipes. It has several thousand miles on it, and by the "seat of the pants" runs pretty darn good. A lot more throttle response/acceleration than the stage I.
I finally had it Dyno-tuned, at ALEF's HD, Wichita, KS
I am confused!
First of all, they charged me for only time (1 1/2 hours), no parts. I presume that means they didn't change any jetting, although I supose they could have adjusted the needle height or the idle-air screw. I suppose I ought to check. I know they made multiple runs--I could hear them.
Dyno results (Dyno was done using STD smoothing):
Air/Fuel mix: Just a little under 14 to one, nearly flat across the rpm range. A small lean area at about 6300, where the mix goes to perhaps 15 - 1.
Max Power: 88.30
Torque peak was 71.87. That's actually less than the bike at a Stage I motor
I have attached the printout from the dyno run. While I wasn't expecting a huge increase in torque, I was perhaps expecting a peak in the mid-80's, instead of barely making 70. Based on other, similarly configured bikes, it looks like I am about 10 ft-lbs too low across the board.
Something seems odd, or is it just me? What should I be looking for on the bike that might be the problem?
I finally had it Dyno-tuned, at ALEF's HD, Wichita, KS
I am confused!
First of all, they charged me for only time (1 1/2 hours), no parts. I presume that means they didn't change any jetting, although I supose they could have adjusted the needle height or the idle-air screw. I suppose I ought to check. I know they made multiple runs--I could hear them.
Dyno results (Dyno was done using STD smoothing):
Air/Fuel mix: Just a little under 14 to one, nearly flat across the rpm range. A small lean area at about 6300, where the mix goes to perhaps 15 - 1.
Max Power: 88.30
Torque peak was 71.87. That's actually less than the bike at a Stage I motor
I have attached the printout from the dyno run. While I wasn't expecting a huge increase in torque, I was perhaps expecting a peak in the mid-80's, instead of barely making 70. Based on other, similarly configured bikes, it looks like I am about 10 ft-lbs too low across the board.
Something seems odd, or is it just me? What should I be looking for on the bike that might be the problem?
Road Master
Joined: Jun 2008
Posts: 948
Likes: 0
From: Oklahoma City
I don't know much about the engine works etc..
But I remember hearing that with the cam upgrades you tend to sacrifice low end torque for a gain in HP.
But I remember hearing that with the cam upgrades you tend to sacrifice low end torque for a gain in HP.
Last edited by Lindsey141; Apr 5, 2009 at 12:43 AM.
Road Captain
Joined: Mar 2008
Posts: 601
Likes: 6
From: Aruba
What heads do you have on the bike? Most of the better flowing heads and work done to make heads flow better only give better HP and torque numbers on the top end. Also, the stock 1200 heads are the worst ones out there. I think the HP & torque numbers you posted look pretty close to what would be expected up to just short of 7k rpm. At that point both curves die. Is that a rev limiter you're hitting or is that where the motor quits making HP?
For your application, the new carb isn't going to give you any better numbers, but it will give you much better throttle response than the stock carb.
Normally when you pay for a dyno, they run the vehicle and give you the results. They don't do much in they way of fine tuning, rejetting or anything. They give you the numbers and you make the adjustments and take it back and have them run it again. If you're looking for them to set up the motor, you need to find a shop that will do that and then let them know that's what you're looking for.
Finally, if you were making over 70 ft/lbs of torque with just a stage one installation, that's a whole lot more than I would have expected. Your statement that the bike feels faster now leads me to believe that you weren't making those numbers before.
For your application, the new carb isn't going to give you any better numbers, but it will give you much better throttle response than the stock carb.
Normally when you pay for a dyno, they run the vehicle and give you the results. They don't do much in they way of fine tuning, rejetting or anything. They give you the numbers and you make the adjustments and take it back and have them run it again. If you're looking for them to set up the motor, you need to find a shop that will do that and then let them know that's what you're looking for.
Finally, if you were making over 70 ft/lbs of torque with just a stage one installation, that's a whole lot more than I would have expected. Your statement that the bike feels faster now leads me to believe that you weren't making those numbers before.
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