Thanks for this posting. I am NEW to the forum and to a BMW motorcycle but have been working on motorcycles for 48 years. I set my TB's with the TWINMAX today but the one thing I noticed was at idle, the meter swung to one side. The cables and TB butterflies are syncronized but now I will try your method to get the Idle stabilizers in sync. Thanks!

 

At idle the TB balance is determined by the adjustments of those blue paint sealed screws on the TB because there is a bit of slack in the cables (it should be, anyway). When you open the throttle, the sync is based on the TB cables adjustments. However, even if the butterflies stoppers and the cables are properly adjusted, if the valves clearances are not correctly adjusted the TBs won't be balanced. Some people completely remove the slack off the cables so the butterflies will never sit on the stoppers, but that may create an unstable adjustment at idle over time.
If you remove the rubber caps off those air connectors where you plug the Twinmax hoses on and put a hose between them you may improve the TB balance at idle. I tried on my bike but because the TBs were in balance it made no difference so I put the caps back on.
To be honest I have no clue why BMW did not design the engine with only one TB in the middle, placed at equal distance between the cylinder heads, which would fuel both cylinders. The old VW Beetle has an awesome boxer engine which has only one TB placed in the middle and which fuels all 4 cylinders. Same has the boxer engine on Porsche. Hmm...... actually I believe I can redesign the air box and do a few other bits to make the conversion.... But who's gonna be able to make the cast etc?!.... Hmm..... It might be one of my next projects.....

 

Guess I've been doing mine wrong since april of 2004. I guess this works but some is not necessary.

 

The procedure I described is actually based on what the computer of the GS-911 does during the synchronization process, and I used this method prior to having a GS-911. The results I experienced were the same.
What the GS-911 does:
Due to the fact that the idle actuators do not have positioning sensors, they may get out of sync for various reasons. The GS-911 spins the stepper motors 3 times to the closed position (just to make sure they reached the full-closed position). This task is replaced by the initial series of unplugging/plugging the stepper connectors, combined with switching on and off the key. When your turn the key off, the bike's ECU will park the steppers to a closed position. When you turn the key one, it positions the steppers to an open valve position depending on the engine and air temperature (so it spins the steppers the other way round). Suppressing the steppers spinning when you turn the key on, they will be firmly pushed to the closed position and therefore synchronized. Ouch... I hope I am not too confusing...

Then you turn the key on, and due to the engine being already warm, the ECU will open the idle actuators to a position calculated based on temperatures, air pressure, etc. At this stage, before starting the engine, GS-911 will lock the idle actuators in that position. This is achieved by unplugging the stepper motors connectors.

At the end of the whole process, you go through the initial procedure of resetting the idle actuators, just to make sure they didn't go out of sync. I melieve this is the bit which Marty considers to be not necessary and I agree but better go on the safe side and do it.

The bottom line is that you manually perform these two functions of the GS-911: resetting/synchronizing the idle actuators and locking them during the process of adjusting the throttle bodies.

The initial maximum slack you have to give to both TB is needed for checking if the butterflies are synchronized at idle based on those screws with blue seal paint on them. YOU NEED TO MAKE SURE THAT THE IDLE ACTUATORS ARE SYNCHRONIZED AND LOCKED. If the butterflies are not synchronized, repeat the idle actuators re-sync procedure just to make sure they are synchronized and if you get the same result it means someone did the "no-no" thing and adjusted one of the two blue sealed screws (usually the right one). If so, you have to synchronize them (the butterflies). Check first which one has the blue paint seal broken, and work on that one. If you can't figure out which one it is, work on the one which has higher level of vacuum and adjust the screw to open the butterfly (spin clockwise) till it gets in balance wit the other one.

The reason for moving the slack adjustment screw one turn back from the point when you can start seeing that it affects the vacuum level is that without that one turn slack the TB balance at idle may not be reliable and it may be extremely difficult to adjust the TBs to be in balance at idle as well as at higher rpm.

Do not forget that before you attempt to balance the TBs you have to PROPERLY adjust the valves clearances. On one of the forums (can't recall where) there are some very good instructions of how to properly do it (something mentioning to leave the allen (hex) key to freely drop to a stop, etc). I personally use a torque screwdriver which can be adjusted at an unbelievable low level, but the procedure described in that forum is very good anyway.
If you get the valves clearances adjustments wrong, all the TBs sync work will be in vain and you may do more harm than good to the engine.

Good luck and post here if you need any help
Cheers

 

Maybe a little over the top. A simple and effective way to do it is like this:

R1200 TB Sync

 

Maybe not over the top. Although very well documented, the procedure described in the link you provided does not do two things:
1. It does not reset the stepper motors. If they are out of sync they will remain the same (out of sync).
2. Does not place the stepper motors in the correct position when you start doing the adjustments. Disconnecting the stepper motors when the power is off stops the stepper motors to be adjusted to a proper position by ECU in accordance with the engine temperature, etc. During the procedure using the BMW computer or GS-911, the stepper motors are locked in that specific position AFTER ECU positioned them to the correct settings as per ECU maps and input sensors (temperature, air pressure, etc).

The procedure I described in my post is meant to REPLACE the steps done by the BMW computer (or GS-911) so people won't need to pay BMW for connecting your bike to their computer or to pay for a GS-911 if you'd only need it for this. The procedure described in your link SKIPS those steps, so if the stepper motors are out of sync... go figure.

Cheers,
Thedy

 

Dear Jim...We have been wrong all these years. Wonder why we haven't had any problems?

 

Beats me Marty!

While you can park the stepper motors, it really isn't necessary. Calibrating the stepper motors is not really necessary either. Both are ONLY used at idle and just off idle. Otherwise they are not in play. Yeah, you can get a slightly smoother idle, but otherwise you can do the TB sync with nothing more than a piece of clear hose and some water.

But hey what do I know?

 

That's what i do

I made my own Manometer from tubing and some blue coloured brake fluid, i simply hang it on the wall in front of the bike where i can see it quiet easy.
The actual physics of the operation are the same, but i have a bigger clearer device to see the balance.

 

actuators

Yes i am a long time lurker, finally. i scored a new to me 09r12, having idel problem on up to 2200rpm. it sounds like its only firing on one cylinder, runs great under load. thank you for this post, on my way down to sync actuators now. very concerened about pluging in connectors with ingnition hot. thanks folks. UPDATE 1/25/15, it works as the bloke says.

 

TB Sync

Jim and Thedy ,you are both very talented and a wealth of knowledge to us all. It is nice to see two views on the same subject that help us all get a better picture of exactly how the process works. I was unsure of doing this myself but because of both of your comments on the subject and to each other I am now confident in making my Manometer and completing the process.
One question I have is cable adjustment at the throttle grip end. This is where 1mm of free play should be adjusted if necessary if you have loosened the TB adjusters and sync' ed them correct?

Thank you,
Dan

 

Connecting stepper motors while powered up

Thedy,

I liked your (now old) post on mimicking the Gs-911 steps without having one. Now four years have passed without any other Gs-911 work around I can find in the forums. Most people seem to ignore the steppers in the process. If the Gs-911,does it, I’d guess there’s a reason.

Question - should I be concerned that plugging in and unplugging the stepper motors while powered on may cause damage to the motors themselves?

Thanks
Rob

 

For which BMW bikes is this procedure for?
Years? Wethead? Hexhead?

 

Not LC



There's no throttle body sync on LC!

 

Used this to rectify an R1200RT with rough idle and bogging/cutting out at full throttle through the entire RMP range. Worked like a charm after the previous owner spent big money at a shop changing out parts to no avail.