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Mike T

Throttle Body Sync using GS-911

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mike adams

I measured the voltage from the TPS at the minimum throttle position. Using the throttle stop screw, I increased the voltage some to make sure it would always come to the same point that is not zero(like the 1100's). I did not know to reset the computer by disconnecting the battery and moving the throttle through a full open cycle. I will try that next. I was able to balance the vacuum at idle by moving only the right hand minimum throttle screw without doing the computer reset. Balancing the cables was pretty easy. I have not ridden the bike yet. I think all I need to do is reset the computer so the TPS will be in a range it is happy with. Thanks for the info- I will report back. Also, have you ever measured the temperature of the exhaust pipes to see if the cylinders are balanced at idle/loaded?

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Don_Eilenberger

Aside from looking at the color of the pipes - no, I haven't bothered checking the temps. My laser-thermometer doesn't go high enough.

 

I don't worry a lot about balance at idle. I don't ride at idle, and the bike will continuously adjust the idle balance all by itself. The idle quality is really pretty crappy with the current gas sold in the US. I had wonderful idle quality when I was riding in Canada and was able to get non-booze laced gasoline. As soon as I returned to the US - idle went back to imitating a Harley.

 

I don't think getting anal about idle match is worth the effort actually, since watching the steppers using the GS-911 shows the ECU moving them in and out of sync about continuously.

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mike adams

Here is what I did to my R1200RT. First, the exhaust was so hot on the right side that it turned the pipes really dark, so I took the bike to the local(highly recommended) speed shop for balancing. They did not fix the problem. I tried tuning the stop screws to achieve balance at idle. I removed the right side TB and found that the end of the cable at the TB had separated. The silver piece over the very end of the cable had come off. This was causing the right side to idle on mostly the right side TB. Now I could balance the TB's, but I needed the TPS to be set first. Here is some info you won't need, hopefully. At the TPS, the center wire is vio/yel and changes from .852VDC to 5VDC. I set it at .860VDC by adjusting the throttle stop screw and then did the power off reset. Now balanced the right side to the left using a manometer(stepper motors hooked up). Then balanced at 3K using cable adjustments and manometer. The bike starts up and idles fine. Temperature is the same on both sides idling. I can't ride until my back surgery is healed up in two weeks, so I don't know if I messed up the running at speed. I have had a lot of fun so far.

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Wally E

I have been reading this thread with interest, and would like to add my bit, and maybe revive this one.

 

I have a GS-911 (Hexcode HQ is 50kms from where I live BTW), and a Motion Pro mercury tube manometer. My bike is a 2011 camhead R1200R.

 

With the engine at normal temp and idling under control of the steppers, there is a slight offset in the height of the two mercury columns. This is with slack in the cables and both throttle plates resting on their stops.

 

This is where my assumption/theory as to what the ECU/steppers are doing at this point comes in. I would think an equal power balance between the cylinders rather than equal mercury column heights is key here. I don't necessarily believe equal heights mean equal power. I think the ECU must be balancing the power by tweaking the steppers (only at idle of course).

 

Let's say it takes x milliseconds for the LH cylinder to drive the crankshaft through 360 degrees. To maintain an equal power balance, it follows that it should take the RH cylinder the same time to drive the crank through the next 360. I would theorise that the ECU is measuring these two time intervals, and balancing them by tweaking the steppers.

 

I get the smoothest running overall if I adjust the RH cable so as to maintain that difference in mercury column heights as the engine rpm rises above idle.

Adjusting so that the vacuum is equal at mid rpm just compromises the "coming off idle" response. Those throttle plates need to come off their stops at exactly the same moment for the best overall smoothness IMHO.

 

Going through the GS-911 procedure, i.e. parking the steppers first, seems to yield pretty much the same result for me.

 

What do the gurus say?

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dirtrider

Afternoon Mike

 

Tell me you Didn't adjust or move the throttle plate stop screws on a 1200RT???????????

 

If you by chance did then try your best to put them back where they were (maybe match the paint marks back up)

 

Never, EVER move the idle stop screws on the BMW 1200 hexhed/camhead ---- NEVER!!!!

 

Those screws are not even factory set, they are flow set at the TB vendor before shipping.

 

You want to screw up a 1200 just move those sacred idle stop screws.

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Wally E
Afternoon Mike

 

Tell me you Didn't adjust or move the throttle plate stop screws on a 1200RT???????????

 

If you by chance did then try your best to put them back where they were (maybe match the paint marks back up)

 

Never, EVER move the idle stop screws on the BMW 1200 hexhed/camhead ---- NEVER!!!!

 

Those screws are not even factory set, they are flow set at the TB vendor before shipping.

 

You want to screw up a 1200 just move those sacred idle stop screws.

 

Absolutely agree with you dirtrider. Those throttle plate stops should never be touched! Verboten!

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