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Old 07-03-2012, 07:49 PM   #1
VanIsland Rider OP
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Pictorial: How to increase drivability for $2.00

I hope the title got your attention!! I will chronicle the mods that I have done to enhance the low speed drivability of my 2004 R1200GS but first here is my disclaimer: If you do these mods and all your farkles fall off or the bike just up and explodes, don’t whine to me but this isn’t rocket science either.

As a lot of us know, the drivability of our bikes at low speed leaves something to be desired. I have “experimented” with a few mods both on this bike as well as a previous EFI sport bike I owned and ended up with a much better running bike. I will describe two mods which made all the difference, reduced compression braking, reduced/eliminated exhaust popping, increased low rpm drivability, increased low rpm torque, and lastly no detriment to fuel economy. Sounds like a lot for two bucks!! Read on.

None of the following is new in any way but applying the principles to the 1200 will make it a lot more fun to drive. These bikes are setup to run very lean from the factory and this is what makes them a handful at times. The following mods are aimed at richening up the low speed fueling.

Step 1

The throttle position sensor on an EFI bike is the first area to increase drivability. The factory settings on adjustable TPS units are set very lean (listen up non 1200 owners) and by loosening the adjustment screws and “adjusting” (a very small amount-mm’s) them to obtain the highest idle speed will place the bike on a richer portion of the fueling curve reducing all the negative drivability issues described above. This will require adjusting the idle speed back toward normal for your bike. If the rider can tolerate a slightly higher idle speed, let’s say 1500 rpm, the extreme engine braking will be reduced even further. On the R1200GS, the TPS is non adjustable, or is it?


Remove the screws holding the TPS in place

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Next gently push out the metal inner sleeves and put them away to reverse the mod if desired

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Add a couple of SS washers and reattach the unit

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Now while tightening the TPS back into place, rotate the unit in a clockwise direction as far as the screws will allow and snug the screws down being careful not to over tighten and crush the TPS

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Start the bike and you will note a higher rpm at idle. Shut the bike off and restart it. In my experience, the computer will now relearn the proper idle speed and restore it ( it did on mine!!)

This mod alone will improve all the negatives we live with on this bike, but just like the infomercials, “Wait, there’s more!!”

Step 2

The idea of altering the the signal of the inlet air temperature sensor by increasing the resistance seen by the computer is no new idea in any way. This mod is common within the automotive enthusiast community as well. There are commercial devices which provide the same effect using different means and they do provide an improvement in performance.

After studying the various means to accomplish this, I created a simple test unit comprised of only a variable resistor (potentiometer) and wired it in SERIES with the air temperature sensor at the air box. This allowed me to try various resistance settings ranging from 5000 ohms to 10,000 ohms. Adding a fixed resister in series with the temp. sensor isn’t the most elegant way of accomplishing our goals but it works!!

Untitled

After trying various settings, I found that for my bike, 6000 ohms was optimal. Once this was determined, I soldered in the closest fixed resistor (hence the $2.00) which was 5600 ohms in SERIES with the air temperature sensor. It dosen’t matter which of the two wires you cut the resistor into, it is in SERIES right?

This “experiment” lasted over a few months and incorporated both road trips as well as daily commuting. The last fuel consumption I calculated based on a 300 km two-up road trip was 53 mpg (imperial gallon).


So let’s get on with it. First remove the coverings and seat on the left side of the bike and find the air temperature sensor harness

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Untitled

Cut either of the two wires and solder in the resistor

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I wanted a water tight seal so I covered the union with liquid tape

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“Well that’s all folk’s”, it worked for me and I hope this helps others. I would suggest making a trial unit with a variable resistor like I have done and determining the optimal resistance for your bike but the values that I have quoted should work for any bike of the same generation as mine. These mods should work on any EFI bike, although the resistance values may differ.

I have no desire to debate the principles described in this article, I only wished to share what I have done to my bike. I would urge the readers who are contemplating these mods to do some research of their own.

Good Luck!
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VanIsland Rider screwed with this post 07-15-2012 at 03:03 PM
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Old 07-03-2012, 10:04 PM   #2
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I love this type of owner R/D, i would never be game to be the first! Well done.
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Old 07-03-2012, 10:18 PM   #3
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Thanks!!
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Old 07-03-2012, 11:51 PM   #4
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the problem with only the 6K resistor in series is it will provide a lower temp signal at all times (when in open loop), but when ambients are getting low that can result in over fuelling. That is why the modules you can buy and plug in also have a parallel resistor, which brings the lowered signal back to normal when you approach 0C ambient.

I have the accelerator module cable, and if I remember well i measured the cable to have:

a variable resistor in one lead:
- at room temperature (30C): 6k ohm
- out of the freeezer (should be -18C): 24k ohm
If these values are correct, and the thing is linear, your additional 6k resistor drops the temp by 16C.

and a fxed 46k ohm one in parallel (eg between the leads)
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Old 07-04-2012, 02:48 AM   #5
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Quote:
Originally Posted by VanIsland Rider View Post

The throttle position sensor on an EFI bike is the first area to increase drivability. The factory settings on adjustable TPS units are set very lean (listen up non 1200 owners) and by loosening the adjustment screws and “adjusting” (a very small amount-mm’s) them to obtain the highest idle speed will place the bike on a richer portion of the fueling curve reducing all the negative drivability issues described above. This will require adjusting the idle speed back toward normal for your bike. If the rider can tolerate a slightly higher idle speed, let’s say 1500 rpm, the extreme engine braking will be reduced even further. On the R1200GS, the TPS is non adjustable, or is it?


Remove the screws holding the TPS in place


Start the bike and you will note a higher rpm at idle. Shut the bike off and restart it. In my experience, the computer will now relearn the proper idle speed and restore it ( it did on mine!!)
I like the way you think

Just confirming that the idle was restored after that mod?

I have a Boosterplug fitted which improves things - I would assume that the TPS mod would enhance that again...

viz
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Old 07-04-2012, 05:21 AM   #6
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Another simple adjustment to improve the bikes drive-ability at small throttle openings is to take as much slack as possible out of the throttle cables. It worked wonders on improving the feeling of sudden engine braking when closing the throttle, & smoothing the transition back open.
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Old 07-04-2012, 07:50 AM   #7
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Gompie
-Your estimate of reducing what the computer see's by 16 C sounds about right (I also checked the variation of the air temp sensor at varying temperatures from 20 C to -15C) but remember, we are trying to titrate the resistance to effect not an absolute temperature.
-The air temp sensor is a NTC thermistor and with the fixed resistor in series, the system as a whole retains some of the NTC thermistor properties
-I commute daily (except when it snows!) with ambient temps from -5C to 25C here on the "wet coast" and the bike runs great, no over fueling noted

Viz
-Thanks
-I had to start and stop the bike a couple of times but the computer will reset the idle speed to normal
-I tried adding the device you mention but the overall effect suprisingly wasn't as good so I removed the device

bemiiten
-You are right on the money but I didn't want to mention it as doing this (and I tried it) on the 1200 seems to confuse the computer and by opening the throttle body a little too much results in a high idle speed that the computer can't seem to compensate for but I have used this technique on a simpler EFI bike and it worked perfectly.
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Old 07-04-2012, 08:14 AM   #8
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Originally Posted by VanIsland Rider View Post
...“Well that’s all folk’s”, it worked for me and I hope this helps others. ...
Simply brilliant!
Most of all, I like the "undo-ability" of the mods. Well done.

As a minor suggestion, I'd be worried that the sensor may vibrate off-position without the locating sleeves (without putting a death-squeeze onto the mounting screws). Did you have such issue? I am thinking about playing with this mod; I may just shove something into spaces in the slots, next to the screws - even toothpicks would do.

Quote:
Originally Posted by Gompie View Post
... i measured the cable to have:
a variable resistor in one lead:
- at room temperature (30C): 6k ohm
- out of the freeezer (should be -18C): 24k ohm
and a fixed 46k ohm one in parallel (eg between the leads)...
The cable you are referring to, does in plug in instead of the air-temp sensor, or in line with it?
The numbers you are referring to, are they measured with the air temperature sensor connected, or just that adapter?
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Old 07-04-2012, 08:42 AM   #9
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Robert
-Thanks
-Good point, when I first made the TPS sensor "adjustable", I thought the same and placed a couple of pieces of plastic to prevent the sensor from moving but subsequently, it dosen't seem to move without.
-Let me know how it works for you
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Old 07-04-2012, 08:55 AM   #10
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Quote:
Originally Posted by VanIsland Rider View Post
bemiiten
-You are right on the money but I didn't want to mention it as doing this (and I tried it) on the 1200 seems to confuse the computer and by opening the throttle body a little too much results in a high idle speed that the computer can't seem to compensate for but I have used this technique on a simpler EFI bike and it worked perfectly.
I only adjust tight enough to remove the slack, not enough to change the idle.
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Old 07-04-2012, 09:09 AM   #11
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Quote:
Originally Posted by rdwalker View Post
The cable you are referring to, does in plug in instead of the air-temp sensor, or in line with it?
The numbers you are referring to, are they measured with the air temperature sensor connected, or just that adapter?
The cable goes in series (eg unplug original, plug it the new wire onto the sensor, and connect both wires. It's just 4" long. c Both resistor are inside one connector, soldered on the connecter pins Just measured it again:
the variable one: 8.5 k ohm at 25C
the parallel one: 46.5 k ohm

I wanted to know how it worked to see if i could easily put an on/off switch in. But not easy to switch two resistors at the same time, and it would interrupt the signal, not sure how the bike reacts on that. Now i have a 2010GS, and it's currently not on the bike as it seems to work much less on the OHC engines.
But if you use only the series resistor, it's easy to make it switchable, just use the resistor to bypass the switch. Then no signal interupt either.
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Old 07-04-2012, 06:27 PM   #12
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Your TPS mod + Accelerator module + Bikemaster airfilter + Yosh exhaust finally =s a bike I can live with. It even shifts better! Thanks. Now if someone can come up with some suspension mods that don't cost an arm and a leg.
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Old 07-04-2012, 06:48 PM   #13
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BaddAndy
-Very cool, glad I could help!!
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Old 07-15-2012, 11:30 AM   #14
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As far as the extra room around the TPS screws ( if it should concern anyone) consider using a LITTLE clear, non-hardening sealant. Bathroom grade may be a touch better, as it is water proof.

WELL DONE VanIsland Rider.

Sounds like you may have a KLR back ground.....good upgrade for near nothing.
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Old 07-15-2012, 11:48 AM   #15
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Thanks Woflgang55 , no KLR, just like screwing with things and hopefully making them better!!
Bry
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