Author Topic: Throttle Body Synchronisation 2012 GSX650F  (Read 1154 times)

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Throttle Body Synchronisation 2012 GSX650F
« on: July 04, 2016, 01:07:45 AM »
After unsuccessfully trying to eliminate the harsh throttle on/off transition on my bike with a O2 Sensor Eliminator, I followed the suggestions of others and did a synchronisation of the throttle bodies. Here is a summary of my method and results;

1) I studied the procedure I found in a 2009 service manual that I downloaded online. I believe all of these bikes are essentially the same so I believe the information to be relevant.
2) The manual gives 2 options to do this procedure, one using the Suzuki SDS tool (page 1D-16) and the other using the dealer mode select switch (1D-18). I used the dealer mode option.
3) Following instructions, I lifted the tank, disconnected the IAP hoses and connected the manometer that I made.
3) I started the engine but discovered that it would not idle with the IAP sensor disconnected.

*Deviation from service manual, at this point, I installed a vacuum "T" into the right hand outer manometer hose and re-connected the IAP sensor. After this modification, the engine idled as per usual.
 Please also note that at this stage, the service manual does not indicate which if any of the throttle bodies should be left "as is" and used as a reference for the other three. Other bikes require a specific reference and I believe it would make sense on this bike as well.

4)After the bike reached operating temperature, I made the adjustments to the air screws to attempt equilibrium among all four. I noticed that the two throttle bodies on the left and the two on the right seemed to react in pairs where one would rise and the other fall when one was adjusted but this did not happen across all four. At this stage I had the left two in balance and the right two in balance but the "pairs" were not in balance. Since I did not want to start turning the air screws a significant amount for fear that I may create an overly rich or lean mixture in any one cylinder, I did a bit more investigation...

Deviation from service manual,  at this point, I noticed a mechanism between the second and third throttle bodies where the throttle cables attach. At first I believed this to be a screw for setting the idle but closer inspection made me believe that it offset the throttle opening between the left and right pairs of throttle bodies. I turned this screw slightly and it was immediately evident that this screw does offset the two pairs relative to each other. I will call this the "throttle body pair offset screw" for the remainder of this document.

5) I adjusted the "throttle body pair offset screw" (make sure you hold the throttle closed while doing this!!!) and observed the results on the manometer. The results were immediate, stable and linear. I now had 4 levels that were for all intents and purposes identical.

6) I disconnected my dealer switch, manometer, reconnected the IAP hoses and put the tank, seat and side covers back on. Time to test ride!

I was fully prepared for this to be another failed effort but to my surprise, it was a success. I now have a proper smooth transition from throttle on to throttle off at any rpm and in any gear. There is also the added benefit of the elimination of a rough spot between 5000 and 5500 rpm where the motor previously vibrated significantly and I avoided coasting along in this rpm band.

Thanks to all who offered insight and knowledge in my previous long thread.


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Re: Throttle Body Synchronisation 2012 GSX650F
« Reply #1 on: July 04, 2016, 01:46:01 PM »
Almost how  I did it.

I've got the Carbtune set, and also use the T piece on the most right cilinder.
Because the air-screw of this cilinder won't turn... all others must be synchronised to this one.
Result is the same,  smooth on the throttle.

I never messed with the O2 sensor or pair system, just let them do their jobs, they work perfect.

If you do the synchronising correctly, the popping of the aftermarket exhaust is almost gone.
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