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Discussion Starter #1
I have been reading about Booster Plug and how it smoothes out the throttle response on our motorcycles. Been looking at the working principle and see that is a fairly easy thing to rig up once the stock Air Temperature sensor specification is known. If I am not wrong, the stock temperature sensor is just a simple NTC thermistor - negative temperature co-efficient one where the resistance decreases as temperature increases. So, if another thermistor with a close enough NTC value is installed in series, the temperature seen by the ECU should more or less see a constant drop in temperature, right?

So, anyone here knows the stock Air temperature sensor specification?
 

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I have been reading about Booster Plug and how it smoothes out the throttle response on our motorcycles. Been looking at the working principle and see that is a fairly easy thing to rig up once the stock Air Temperature sensor specification is known. If I am not wrong, the stock temperature sensor is just a simple NTC thermistor - negative temperature co-efficient one where the resistance decreases as temperature increases. So, if another thermistor with a close enough NTC value is installed in series, the temperature seen by the ECU should more or less see a constant drop in temperature, right?

So, anyone here knows the stock Air temperature sensor specification?
booster plug wedsite explains why it dont work the same
 

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Discussion Starter #3
booster plug wedsite explains why it dont work the same
I did read the tech section for Booster plug(big thumbs up for booster plug!!) and know why it is not just a straight forward task of adding a simple resistor to the Air temperature sensor. I also know that if the sensor used on our bikes is a thermistor, and its value is known, we can add another one is series to it which will effectively double the resistance at the same temperature. Since thermistors have a non linear temperature to resistance curve, the second thermistor would just bump the curve to twice the actual value, and exhibit a consistent temperature drop at the ECU. Atleast that is the theory. Once I get to lift the tank up and added an extension to the existing plug, the experiments will begin.

Maybe its just a placebo effect, but this morning's ride was smooth. Should I credit it to the cooler temperature (51F) compared to the regular 65F to 70F during mid-day?
 

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Discussion Starter #4 (Edited)
See the attached table for a Suzuki Forenza (just an example until I find a motorcycle one) :



if we add another thermistor of the same kind, we will pretty much double the resistance seen by the ECU. And corresponding to the newly doubled up resistance, you will see the temperature is more or less a constant -15C compared to ambient.

So, once I find the stock IAT sensor values, booster plug is an easy DIY test.:nerd:
 

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You may be on to something. -15C is in the ballpark of the -20C Boosterplug claims. Curious as to why they have a different part number for 2017 GSXS vs. 2015-2016.
 
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You may be on to something. -15C is in the ballpark of the -20C Boosterplug claims. Curious as to why they have a different part number for 2017 GSXS vs. 2015-2016.

There are 4 options on the Booster Plug site. 1 each for the 15 - 16 N or the F, and same for the 2017 N or F variant.
The mystery is what would be different between the Naked and Faired under the fairings?
Surely wind flow over the motor air intakes would not be that different that Suzuki has different air intake sensors for each variant too ?


Rob.
 

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Suzuki part numbers are the same. I suspect the folks at BP just want us to think we are getting something designed specifically for our exact bike. So why no separate part number for red or blue?

A quick spot check showed the air temp sensor is the same as on the V-strom 650 and 1000, and probably a number of other models.
 

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Discussion Starter #9 (Edited)
Any use ? ...

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Perfect!!, Thanks for that info, is that in the Motorcycle manual? I will look for an equivalent thermistor that can work for us. Now, need to find some connectors that can go between the stock harness and the IAT plug and we are good to setup a plug n play solution. If anyone can help identify the connector and a source, it would help this roll much faster :D .

I was also thinking that if the fueling at a particular temperature works very well, a simple potentiometer/variable resistor can be plugged in replacing the stock IAT sensor and "hand-adjusted" to whatever feels good :nerd:
 

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When the temp hits 80C, I think I'll be taking the car with AC.

I guess a potentiometer could be used. You'd need to chart out the resistance vs. temperature, then figure out what value pot, then make some sort of dial for the temp. Then you would have to remember to adjust it for different temps or risk running too rich.
 
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Discussion Starter #11
Approximations based on the previous comments:

Based on the data from the manual, the stock Thermistor is a NTC with 2.2K ~ 2.5K @ 25C - 10% tolerance one.

Possible series Thermistor is a NTC type 2.7K @25C which should give a close enough 20C difference to the ECU across temperature values. The difference will be markedly less at temperatures < 0C, but at that point I believe the throttle issue would no longer exist.

Here is a thermistor with the desired value : https://www.digikey.com/product-detail/en/vishay-bc-components/NTCLE100E3272HB0/BC2312-ND/769422

Googling is on to find the connectors now.
 

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Discussion Starter #12
When the temp hits 80C, I think I'll be taking the car with AC.

I guess a potentiometer could be used. You'd need to chart out the resistance vs. temperature, then figure out what value pot, then make some sort of dial for the temp. Then you would have to remember to adjust it for different temps or risk running too rich.
True, and I almost forgot the reason why another thermistor is needed - to prevent premature detonation in higher temperatures. A resistor would not account for the higher reaches of air temperature - probably when the difference in Air temperature to the fixed temperature value exceeds 30C - engine problems could arise due to this.

Anyway, back to the thermistor theory.
 

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For connectors, a couple of good sources are Eastern Beaver and Cycle Terminal. EB is in Japan but has good service to the US, and maybe a better selection than CT.
 
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I have a question regarding the IAT sensor: what will happen if the sensor is removed from airbox and it is placed somewhere else, out of the airbox, but in contact with fresh air (let's say it will be placed under the headlight).
 

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I have a question regarding the IAT sensor: what will happen if the sensor is removed from airbox and it is placed somewhere else, out of the airbox, but in contact with fresh air (let's say it will be placed under the headlight).
It shouldn't really matter since the air going through the airbox should be approximately the same temperature as the outside air. Maybe in practice it is a little higher, especially if you're sitting in traffic.
 
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Maybe someone who has a software interface which can read the temperature inside the airbox will be curious to compare it with the outside air temperature. I'm thinking there is a difference between those two temperatures (it's higher inside the airbox?!). Maybe placing the IAT sensor outside the airbox it will help with the throttle issue.
 

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Discussion Starter #17
For connectors, a couple of good sources are Eastern Beaver and Cycle Terminal. EB is in Japan but has good service to the US, and maybe a better selection than CT.
Thanks for those pointers, placed order for two pairs of connectors (website said they dont ship < 10$ , so had to order two sets) from Eastern Beaver. Looking for any prepackaged thermistor, else I will just buy a few from digikey and try them out. Hopefully my first service will be complete by the time I get all parts for this experiment.

Also, I am trying to observe the bike's behavior early in the morning and later in the day when it is much warmer. I *feel* that there is a bit more surging behavior in the evening compared to morning. Once I get the connectors, I will build a test base to validate this for sure.
 

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Thanks for those pointers, placed order for two pairs of connectors (website said they dont ship < 10$ , so had to order two sets) from Eastern Beaver. Looking for any prepackaged thermistor, else I will just buy a few from digikey and try them out. Hopefully my first service will be complete by the time I get all parts for this experiment.

Also, I am trying to observe the bike's behavior early in the morning and later in the day when it is much warmer. I *feel* that there is a bit more surging behavior in the evening compared to morning. Once I get the connectors, I will build a test base to validate this for sure.
Which connectors did you determine were the proper ones?
 

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Discussion Starter #19
Which connectors did you determine were the proper ones?
The 2P040WP-HX series. I went by the previously shared image of the IAT and the ones on the website and eye -balled it to be the right one :D . Come to think of it, I should have waited till I could confirm for sure. We will see.
 

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If all this works out, it would be relatively simple to install a switch to short the added thermistor to return to stock arrangement. Would make comparing very easy.
 
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