Speedometer Adjustment After 30T/70T Swap

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Apr 10, 2019 | 12:14 PM

easyissy

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From: San Pedro, CA (So-Cal)

Speedometer Adjustment After 30T/70T Swap

I did the 30T/70T swap on my 2016 Streebob and ran into the speedometer being off.

So I purchased the Dakota Digital SIM-1A and hardwired it into the ECM per the manufacturer's directions.

A couple thing I learned that I figured I'd pass along just in case someone was contemplating this same fix.

After the install you have to ride the bike while adjusting the speedo which was a feat in itself.

You end up losing all the gear indication on the speedo's gear/RPM display. (losing cruise control and 6th gear indicator light is mentioned by the manufacturer if you go beyond the 5% correction)

Also your speedo goes dead once you go over 90mph.

Below is the explanation the manufacturer gave me.

With newer bikes, the speed is off from the factory at about 4% to 5%. In order for the cruise and 6th gear light to work the speed must stay about 3% off. Drastic pulley changes can make this percentage be greater. We cannot modify the range of what the ECM is looking for.

The speed drops out over 90mph because the SIM-1A needs 12V power like found on the older bike speed senders vs the newer bikes only have 5v power. This causes the SIM-1A to drop out at higher speeds.

It seemed like a waste of $100 to me but at least my odometer will be correct.

Does this happen when adjusting the speedo with the Power Vision?

If not, I might end up going that route.

Apr 10, 2019 | 12:32 PM

byrdman.45

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From: Missouri

Agree trying to adjust while riding is a pita especially with them little buttons.The older one on my Sportster has nickel sized buttons and was quite easy.

Did lose the 6th gear light, but that was fine as long as speedo was close to right.

It's an 09 Low Rider so speedo still works at over 90.

Apr 10, 2019 | 04:15 PM

Jay Guild

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From: Iowa

I went with the ThunderMax that replaces the ECM, allows to set the speedometer, and tune the bike.

Apr 10, 2019 | 04:49 PM

easyissy

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Joined: Oct 2016

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From: San Pedro, CA (So-Cal)

Quote:

Originally Posted by Jay Guild

I went with the ThunderMax that replaces the ECM, allows to set the speedometer, and tune the bike.

How do you like it? Pros and Cons?

Seems like a good alternate to the Power Vision with Auto Tune.

Apr 11, 2019 | 10:11 AM

Jay Guild

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From: Iowa

Quote:

Originally Posted by easyissy

How do you like it? Pros and Cons?

Seems like a good alternate to the Power Vision with Auto Tune.

Pros, it comes with the wide band O2 sensors standard instead of having to get the Target Tune or other add ons like most tuners. It is not a piggyback system so the ECM is not being manipulated with signalling. Makes it so there are fewer parts that can fail and doesn't take up room under the seat like piggy back systems. You can adjust anything the SERT or PV have except knock sensing. It auto-tunes on the fly with constraints that set by the user instead of tracking data and having to connect a computer to get suggested modifications and then making the adjustments like the PV.
Cons, if you have used other tuners that have target AFRs by RPM and kPa instead of throttle position there is a bit of a learning curve so most Dyno tuners will not tune your bike with a ThunderMax on it. You do have to adjust your AFRs manually to get your desired milage vs enginetemp/HP. If it goes bad you the bike will not run where a PV you can disconnect from the system and have the stock ECM try to get it home. Considering the stock ECM won't have your tune it may not run well or for very long but that more depends on how modified your engine is.

Last edited by Jay Guild; Apr 11, 2019 at 10:21 AM.

Apr 11, 2019 | 12:38 PM

billib1954

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Joined: Nov 2013

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From: virginia

I have a dakota digital speedo with tach on my 2012 fatbob. I just used to buttons on handle bar to make the 13% adjustment, then verified with GPS. Of course it was about 400$, but the tach is nice too and gear indicator is retained. It flashes as you near redline for shift light. I have the old SE tuner..

Last edited by billib1954; Apr 11, 2019 at 12:41 PM.

Apr 12, 2019 | 11:34 AM

easyissy

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From: San Pedro, CA (So-Cal)

Quote:

Originally Posted by billib1954

I rarely use my speedo on my Streetbob that would justify a $400 replacement since it's on the tank. With 14" T-bars and my fairing with a 18" windshield looking down is done rarely.

I just figured for $100 I would get something that actually worked well. Guess not.