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Synchronize your Throttle Valves

Started by gsxbarmy, Monday, 06 February 2017, 12:14 AM

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gsxbarmy

NOTE: This thread is also available to download as a PDF file from the Downloads (General) Section

How to Synchronize your Throttle Valves

As a starter, a quick review of what the manual says....

First balance your injectors using a Vacuum Balancer Gauge (Suzuki part no 09913-13121, although many use the 4-way Carbtune Balancer gauge (http://www.carbtune.com/).

The vacuum gauge is positioned approx. 30° from the horizontal level, and in this position the four balls should be within one ball dia. If the difference is larger than one ball, turn the balance adjusting screw on the throttle body and bring the ball to the same level. A correctly adjusted throttle valve synchronization has the balls in the No. 1 through 4 at the same level.

The problem many have when looking to do this job is - where is the adjusting screw on the throttle body?



First thing to note - Throttle bodies 1 and 2 are connected as are 3 and 4.

There are 2 adjuster screws, they are positioned at the bottom (underneath) of 1 and 2 and the bottom of 3 and 4 (They are a pig and fiddly to get to but once you work out what screwdrivers are best then you can adjust no problem)

Don't forget to remove the wiring plug from the IAP sensor situated on the main spine of the frame under the fuel tank or the engine won’t run very well (It's the sensor that the 4 pipes go to when you remove them from the throttle bodies to connect the vacuum gauges). Also don’t forget to reconnect the wiring plug once you have completed synchronization.

Balance 1 to 2 then 3 to 4 using the underneath screws...Finally balance 1+2 to 3+4 using the adjuster screw between 2 and 3. You only need to move them a tiny amount at a time.

One more tip... All three screws are PHILLIPS Head... Don't adjust the Flat head screw in the middle â€" it’s the Cold Idle!
Nothing to do.............all day to do it....I love retirement :lol:

Andre

#1
Attached are a couple more pics to help you locate the screws.

First pic (showing underside of TB):
#1 is for syncing throttles 1 with 2; #2 is for 3 with 4.

Second pic (TB in place, from above, between 3 and 4):
#3 is for syncing throttle pairs 1/2 with 3/4.

Monarchjock

Could anyone specify a good tool for adjusting the throttle bodies that doesn't put too much pressure on the screws. I find that using a phllips screwdriver needs a bit of pressure which affects the setting.

Andre

#3
I know what you are talking about :frustrated: I don't have/know the perfect tool for that. I use a very short and small socket extension with a fitting phillips socket. Gives me the best feel for the job.

Just remember that there are some screwdrivers with screw holder function. Just has to be short enough. May do the trick :whatever:

seth

only a slightly modified gsx1400
oh and a standard one too

Sethbot Postwhore

Eric GSX1400K3

Dear Brains Trust,

Which TB synchronizer / balancer is best?

The Morgan carbtune Pro 4 column unit

the e-tune electronic version?

Or home made?
I try to take one day at a time, however sometimes several days catch up with me at once.

KiwiCol

I brought the Morgan, works well & has everything in the kit for our bike & also carby bikes.  Instruction manual too.  Only thing I'd add is the bag / case, which was optional.  I made my own, but would of been a good idea to buy the case at the same time.
😎  Always looking for the next corner.  😎

Fieldmouse

Hello all,

Just a quick question on synching. I balanced throttle bodies yesterday. Took off vacuum lines, disconnected IAP sensor. Bearing in mind, my PAIRS system hasn't been blanked off, do I need to block off the extra vacuum line that goes to the PAIRS valve/sensor as well, or if I have disconnected the electrical lead going to IAP sensor, is this sufficient?
Sorry if my mechanical terminology is lacking, so hopefully you may understand what I'm asking.
I did notice, that pulling that extra lead off the intake line, and putting my finger on it to block it off(engine running) it definitely made a difference to the carb balance readings. (IAP sensor disconnected)

Thanks in advance.

BTW, bike is running fine after balancing. I followed both advice from here, and cross referenced with my Haines manual.

Andre

I always block it. It is easy to do and eliminates a source of error.

Fieldmouse

Quote from: Andre on Saturday, 04 April  2020, 12:58 PM
I always block it. It is easy to do and eliminates a source of error.

Thanks Andre 👍

Hooli

In theory you don't need to as it should be a sealed valve, but I'd block it too just in case.

Andre

The basic thought of synchronizing the primary throttle valves is to have an equal sitting and opening of the valves. The common ways of synchronizing is an INDIRECT method. Several variables, such as a vacuum leak or "vastly" different cylinder head valve clearances, can influence the result.

If/when you have the throttle bodies off you can DIRECTLY synchronize the primary throttle valves. That goes for the SECONDARY throttle valves as well as there is no indirect way to do this.

Hooli

Indeed. Many years ago when I rebuilt one of Vicky's 14s after a garage were busy trying to rip her off repeatedly while doing it wrong I did them directly.

They were so far out the bike was idling on two cylinders, the garage were trying to claim 4 1/2 hours work to check the throttle bodies. Which was the final straw & I told her to get it home & I'd do it properly, but that's another story. Back to the subject, I popped the TBs off & directly balanced them by adjusting them so a 3mm (I think) drill slid under every butterfly with the throttle shut. Refitted them & it run fine.

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