Throttle body sync/balanced cylinders

[mcatrophy]

Bump.
I am still waiting for some input / help, Gang. See the question two posts above. Any insight will be greatly appreciated!

Best I can do is quote from the Haynes Manual:

On the 2013-on models locate the air screws in the throttle bodies and identify the white painted one - this one is the base to which all the others are matched, and cannot itself be adjusted. If the vacuum readings on the others vary by more than 10mmHg from the white one, adjust the throttle bodies as required by turning the appropriate air screw until the readings are the same as the base. If an air screw is inadvertently removed, screw it in until it seats lightly, then back it out 3/4 of a turn, and make any fine adjustment to its setting according to the gauge reading. Note: Do not disturb the throttle valve adjustment screws situated between the throttle bodies.

 

[FJRTom]

Thanks to all who replied. I will search more diligently for the adjustment screws the next time I am under the tank!

 

[leclairk]

I have a copy of Fred's RDCUA TBS procedure. I know where the vacuum take off points are and where the air bypass screws are but on a Gen II where are the butterfly valve screws? Anyone with a pic or a link to a pic? Are they in the same location on a Gen I vs Gen II because Fred has pictures of the Gen I?

 

[Fred W]

Yes, the butterfly adjustment screws are in the (generally) same location on all generations. They essentially adjust the linkage's alignment between the throttle bodies, and the #3 TB is hooked directly to the bell crank that is controlled by the throttle cables.

I've made a further change (possible improvement) in using the RDCUA TBS procedure that I am putting out there for other folks to try if they are not fully satisfied with their results using the procedure as it is. What I found gradually over the past few years is that after adjusting the butterflies with the air screws closed and engine at idle, I was not getting rid of all of the buzziness anymore like I had achieved earlier on.

I theorized that I may have some crud building up on some of the throttle plates that are affecting the air flow at idle more than it would at some greater throttle opening. On my last oil change service I decided to try this:

Closed down the 4 air screws fully and balance the vacuum via adjust the linkage screws with the engine running at ~4k rpm. I was able to get them very close by iteratively running the engine up to 4k rpm for 3-5 seconds at a time, adjusting, and then rechecking.

This resulted in a somewhat mis-balanced vacuum at idle, which I then balanced out by opening all 4 screws 3/4ths of a turn and then balancing the air screws (and adjusting idle speed) from there.

The end result was a balanced vacuum at idle that does not vary much as the throttle is opened. It also produced the desired reduction of vibration at cruising rpms (4-5k) that I was looking for.

So there you have it, another way to skin the TBS cat.

 

[Tiger9650]

FJRTOM

I just did the TBS on my 2013. Yes, it has the air adjustment screws. The left cylinder screw is painted white and is the standard to match up the other three cylinders. There is not an idle adjustment screw, it was removed on the 2013.

 

[kiwiaudio]

Bump.
I am still waiting for some input / help, Gang. See the question two posts above. Any insight will be greatly appreciated!

Best I can do is quote from the Haynes Manual:

On the 2013-on models locate the air screws in the throttle bodies and identify the white painted one - this one is the base to which all the others are matched, and cannot itself be adjusted. If the vacuum readings on the others vary by more than 10mmHg from the white one, adjust the throttle bodies as required by turning the appropriate air screw until the readings are the same as the base. If an air screw is inadvertently removed, screw it in until it seats lightly, then back it out 3/4 of a turn, and make any fine adjustment to its setting according to the gauge reading. Note: Do not disturb the throttle valve adjustment screws situated between the throttle bodies.

So did you screw the white head air screw that "cannot be adjusted" home along with the others before starting the procedure. Was it installed with Loctite from the factory perhaps ?

 

[kiwiaudio]

Wondering what balancing tool to buy and I just watched the motion pro video

https://www.oemcycle.com/Item/product/900127976/?utm_source=BNGA&utm_medium=cpc&utm_term=14271933523&utm_campaign=1706881017

This guy only balances at idle, and he is not real definitive about just what he is adjusting, but he raises a point about calibrating the tool at a low setting first, or the fluid can be sucked out of it if your bike has high vacuum. Im wondering how high the reading goes at the 4K point where we adjust the TBS.

Is this the tool most of you use, or is there a better one ?

 

[Fred W]

This is what many of us use. No danger of sucking fluid in as there isn't any, just metal bars that get sucked up to indicate relative vacuum. What the absolute vacuum is (in inches of mercury) does not really matter.

Morgan Carbtune

 

[mcatrophy]

...

On the 2013-on models locate the air screws in the throttle bodies and identify the white painted one - this one is the base to which all the others are matched, and cannot itself be adjusted. If the vacuum readings on the others vary by more than 10mmHg from the white one, adjust the throttle bodies as required by turning the appropriate air screw until the readings are the same as the base. If an air screw is inadvertently removed, screw it in until it seats lightly, then back it out 3/4 of a turn, and make any fine adjustment to its setting according to the gauge reading. Note: Do not disturb the throttle valve adjustment screws situated between the throttle bodies.

So did you screw the white head air screw that "cannot be adjusted" home along with the others before starting the procedure. Was it installed with Loctite from the factory perhaps ?

Not sure who you are asking. I've never done this (not got a '13). If I was doing it, I'd leave that white one alone, do everything relative to that, unless I had a very good reason to do otherwise.

 

[Fred W]

...

On the 2013-on models locate the air screws in the throttle bodies and identify the white painted one - this one is the base to which all the others are matched, and cannot itself be adjusted. If the vacuum readings on the others vary by more than 10mmHg from the white one, adjust the throttle bodies as required by turning the appropriate air screw until the readings are the same as the base. If an air screw is inadvertently removed, screw it in until it seats lightly, then back it out 3/4 of a turn, and make any fine adjustment to its setting according to the gauge reading. Note: Do not disturb the throttle valve adjustment screws situated between the throttle bodies.

So did you screw the white head air screw that "cannot be adjusted" home along with the others before starting the procedure. Was it installed with Loctite from the factory perhaps ?

Not sure who you are asking. I've never done this (not got a '13). If I was doing it, I'd leave that white one alone, do everything relative to that, unless I had a very good reason to do otherwise.

I think he was talking about doing an RDCUA TBS. The one that you adjust the screws strictly forbidden in the manual (highlighted in red above).

 

[kiwiaudio]

Sorry, I should clarify. The first step in doing the pre 2013 RCDUA TDS is to close all the air screws, so this white one on the 13 will have to be closed if we follow procedure. After getting the butterflies parrallel at around 4k, by adjusting those throttle valve screws that we are also not allowed to touch, you then revisit the air screws at idle - Do I have that right ?

Now, Im thinkin closing the screws might be an over the top move anyway - they are not doing much at 4K.

So how about leaving them alone until the last step, and then just tweaking the three non white ones. ?

What do you think?

Fred, thanks for the point towards the Morgan.

 

[Fred W]

You may be right that it is not necessary to close the air screws if you will be adjusting the linkage at 4k rpm. You could try that. The reason I was closing the screws in the RDCUA TBS is I was then adjusting the linkages at idle speed and the screws have a big effect there.

 

[FJRTom]

FJRTOM I just did the TBS on my 2013. Yes, it has the air adjustment screws. The left cylinder screw is painted white and is the standard to match up the other three cylinders. There is not an idle adjustment screw, it was removed on the 2013.

Thank you, Tiger9650! I will be more diligent in looking the next time I'm under the tank!