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05 Stock Fatboy FI
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Discussion Starter · #1 · (Edited)
What I have on my bike is below. So, I setup a laptop, strapped it to the bike and revved it to 6200 1st-3rd gear, attached is the graph. How accurate is this? I hit the rev limit, not sure if that affects anyting, first time by the way in 2500 miles, just said fuuk it. I hate not having a tach tough.

Also, I had the dealer put on the pipe and do the stage I.
 

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SeanHerr said:
What I have on my bike is below. So, I setup a laptop, strapped it to the bike and revved it to 6200 1st-3rd gear, attached is the graph. How accurate is this? I hit the rev limit, not sure if that affects anyting, first time by the way in 2500 miles, just said fuuk it. I hate not having a tach tough.

Also, I had the dealer put on the pipe and do the stage I.
Why don't you take it to a dyno and have a baseline run done?
 

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05 Stock Fatboy FI
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Discussion Starter · #3 ·
I am going to be doing the GMR 98 kit in the next week or so, not wirth the time an effort, it was just more of a curiosity question. My bike is slow, but it does not feel that slow.
 

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SeanHerr said:
I am going to be doing the GMR 98 kit in the next week or so, not wirth the time an effort, it was just more of a curiosity question. My bike is slow, but it does not feel that slow.
Who is doing the 98" build?
 

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I asked the same question and got answers from 5 to 10% difference. The SERT reading lower than a dyno. Of course you could take your bike to every dyno in the state and never get the same answer twice.
 

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MegaGlide said:
And running in first gear ain't gonna tell ya crap.
4th.
That also applies to dyno testing on cars and trucks, 1st gear testing might give you some info just off idle but that's about it.
 

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05 Stock Fatboy FI
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Discussion Starter · #8 ·
Totenkopf said:
Who is doing the 98" build?
I am doing the build my self with the help of a freind. I will definetly bring it in to be tuned.
 

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SeanHerr said:
I am doing the build my self with the help of a freind. I will definetly bring it in to be tuned.
Who's going to tune it?

The reason I ask is, I had a hard time finding anyone in our area that is SERT competent.
 

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05 Stock Fatboy FI
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Discussion Starter · #10 ·
Sorry, I just realized you were so close. I have no idea who is going to tune it, thought about making a run to Bishops in MI, but I have not talked to them yet. I have been calling around and have not found anyone locally that uses SERT, and I just want to go that route so I can get the map.
 

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SeanHerr said:
Sorry, I just realized you were so close. I have no idea who is going to tune it, thought about making a run to Bishops in MI, but I have not talked to them yet. I have been calling around and have not found anyone locally that uses SERT, and I just want to go that route so I can get the map.
You need to plan ahead and get a tuner figured out quick! That is half the battle, building the motor is the straight forward part.

Otto in Sugar Grove is by far the best tuner with the SERT that I've found around here. The problem is, he tunes what he builds. He's not in the tuning business for anything else. Who's heads are you going to use? and are you going to get them ported? Maybe you can work a deal with Otto that way.

If you went with a Power Commander, I'd say take it to Woodstock and have Brad or Mike do it. They are good with the PC.

Heritage has a guy named Mike that Otto trained years ago that is okay but it ain't Otto, if you know what I mean. Now since Otto doesn't have his dyno yet, he uses Mike and he goes there to manage and oversee the tune, guiding Mike along the way.

One of the Dynojet guys lives in Sandwich and is getting a brand new 250i in with all the bells and whistles, setup for simultaneous front and rear cylinder AFR plotting. Otto will have complete access to that dyno. We are going to take mine there to double check the tune, after it gets setup.
 

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SeanHerr,
I know this is a real longshot but............... Since you have a '05 FatBoy and live in Buffalo Grove.

I met a fellow biker on a flight back from Amsterdam last year that fits your description. Was that you by any chance?
 

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05 Stock Fatboy FI
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Discussion Starter · #13 ·
Totenkopf said:
SeanHerr,
I know this is a real longshot but............... Since you have a '05 FatBoy and live in Buffalo Grove.

I met a fellow biker on a flight back from Amsterdam last year that fits your description. Was that you by any chance?
Could not of been, if I went to Amsterdam I probably would not of come back.
 

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SeanHerr said:
Sorry, I just realized you were so close. I have no idea who is going to tune it, thought about making a run to Bishops in MI, but I have not talked to them yet. I have been calling around and have not found anyone locally that uses SERT, and I just want to go that route so I can get the map.
bishops did my heads and unless i misunderstood something they don't do much SERT tuning
 

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SeanHerr said:
What I have on my bike is below. So, I setup a laptop, strapped it to the bike and revved it to 6200 1st-3rd gear, attached is the graph. How accurate is this? I hit the rev limit, not sure if that affects anyting, first time by the way in 2500 miles, just said fuuk it. I hate not having a tach tough.

Also, I had the dealer put on the pipe and do the stage I.
My $0.02 and the opinion of someone who knew a crapload more about dynos and testing than I ever will:

Trying to compare between dyno results (even the same make and model) is an excercise in futility. In the case of the SERT vs the DJ inertia dyno we are talking about results influenced by road conditions (grade) and environmental (head wind, tail wind) that don't come into the picture in a test cell. The math and principles involved are pretty much the same, but each has slightly different assumptions in the calculations used to derive the posted results. If the input parameters and assumptions for either one are reasonably close, each should give fairly repeatable results. Remember, these are tuning tools. What's important is the incremental change(s) seen from one run to the next on the same dyno, same test sequence (day), and same test conditions.

There's lots more valuable info that can be had from a dyno than just the typical WOT 4th gear run. Runs through the gears have their uses as well as part throttle runs and top gear (5th, 6th, whatever) runs. It greatly depends on the skill of the operator/tuner and what the goal is.

Bottom line? Don't get wrapped around the axle on the peak numbers from any dyno run, SERT or otherwise. More important is the shape of the curves and what change has taken place from one run to the next --- did the change in AFR help or hurt power? Does the engine like more or less advance? Does cam X really have better area under the curve power than cam Y, or is the SOP (butt dyno) feel deceiving you into thinking that one is more powerful than the other.

Then you take it out to the track or someplace where you can do timed acceleration runs and see what the changes are in "real" world conditions and try and correlate that to what you see on the dyno --- that's when this stuff really starts to mean something -or- you can slip the operator a few bucks and get a dyno sheet that will make you king of the hill with a lot less effort :>)
 

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vtwin_nut said:
My $0.02 and the opinion of someone who knew a crapload more about dynos and testing than I ever will:

Trying to compare between dyno results (even the same make and model) is an excercise in futility. In the case of the SERT vs the DJ inertia dyno we are talking about results influenced by road conditions (grade) and environmental (head wind, tail wind) that don't come into the picture in a test cell. The math and principles involved are pretty much the same, but each has slightly different assumptions in the calculations used to derive the posted results. If the input parameters and assumptions for either one are reasonably close, each should give fairly repeatable results. Remember, these are tuning tools. What's important is the incremental change(s) seen from one run to the next on the same dyno, same test sequence (day), and same test conditions.

There's lots more valuable info that can be had from a dyno than just the typical WOT 4th gear run. Runs through the gears have their uses as well as part throttle runs and top gear (5th, 6th, whatever) runs. It greatly depends on the skill of the operator/tuner and what the goal is.

Bottom line? Don't get wrapped around the axle on the peak numbers from any dyno run, SERT or otherwise. More important is the shape of the curves and what change has taken place from one run to the next --- did the change in AFR help or hurt power? Does the engine like more or less advance? Does cam X really have better area under the curve power than cam Y, or is the SOP (butt dyno) feel deceiving you into thinking that one is more powerful than the other.

Then you take it out to the track or someplace where you can do timed acceleration runs and see what the changes are in "real" world conditions and try and correlate that to what you see on the dyno --- that's when this stuff really starts to mean something -or- you can slip the operator a few bucks and get a dyno sheet that will make you king of the hill with a lot less effort :>)
I agree vtwin_nut.

Dynos are just another useful simulation tool, especially to get the tune in the ballpark but they don't always correlate well with the real world, especially in racing where the dynamics are completely different from a 900lb drum to 1320ft of track and wind resistance and airflow over the bike/motor.
 

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If you really want to stir the pot, especially for the "butt dyno" or "torque is king" crowds, explain the way an inertia dyno derives it's readings :>)
Inertia dynos measure work --- the time it takes to accelerate a known mass, otherwise known as HORSEPOWER. It then back computes to derive the torque because only an absorption or brake dyno with a strain gage can directly measure torque. in addition, certain assumptions are made with regard to drivetrain mass, gear ratios, etc. and may not be totally accurate depending on the vehicle being tested. Some inertia dynos (not DJ) allow inputs for gear ratios, drivetrain and engine flywheel mass in an attempt to make the readings more accurate --- that can open up a whole new can of worms!
Then hit 'em with the fact that no matter how much torque is applied to an object if there is no movement there is no work being done and the result is 0 horsepower!
Ya need both of them for the motor to be of any use, the more of each one, the better. Since torque will always be greater than horsepower below 5250 rpm those big torque numbers seem to fool a lot of people into thinking that the torque is all they need --- ummm, not quite. Higher torque simply means that you creating more power at a given rpm, and the definition of power is the rate at which work is done. One without the other just ain't possible, pick the one you like to talk about, you still need both of them. Given a vehicle of the same weight and gearing the vehicle with the greater horsepower numbers will out accelerate the vehicle with less horsepower and attain a higher top speed as well ... physics and actual track results say so! The "butt-o-meter" feel can be decieving --- motors with a wide flat power band can be "sneaky fast" in that they don't give that instantaneous "kick in the pants" feel, but they are moving you down the "long black dyno" at a faster rate than the motor with a short, peaky power band.
I will now stand back and watch the fur fly --- popcorn, anyone? :>):whistle:
 

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Awesome! somebody here gets it.........

WOW! we are in total agreement and you are exactly correct about your facts. The DJ does measure work(time to spin 'da drum), aka HP and back calculates torque. I spoke with their engineer about it at a recent show.

Everyone around here gets so hung up on dyno numbers but funny thing about that. A good dyno'ing bike may not be the fastest race bike, for a lot of different reasons. They are useful to get the AFR right in different load regimes though.

I first came across this line of thinking from Bob at RB Racing. He has quite the rant on dynos on his website. He's quite well known for his racing motors, ECU's, turbos, injection systems and exhausts and deriving their design and performance from race applications, like what he calls, the BIG white dyno, aka the salt flats. He also doesn't post any silly dyno charts for the simple reason that there are way to many variables to use it as definitive proof of anything. The real proof is on the track, in the real world.

Again, a useful tool if used properly.
 
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