R1200 series Throttle Body Sync Pictorial

Hiya Jim,

Not one to do a whole lot of my own maintenance, I was motivated while going through all your "how to" threads, which you have do a super job on!

Today I tackled the valve adjustment and throttle body adjustment on my 07 GS. My bike has been idling rough, and backfiring more than I thought it should. The valve job went smoothly, and everything was pretty good except I had a tight exhaust valve on the right side. Easily taken care of with your directions, and I got them all adjusted in less than a hour. Not bad for a rookie.

Ok, on to the throttle body adjustment. I guess I was one of the unlucky ones. My idle on the Twinmax bounced, with a 2 as the center. You say you have never seen that, but I sure did. Lucky me.....

Anyways, I ran the RPM's up, at 2K and 4K the needle was dead center, or too close to worry about. So then I started to look at the idle you say there is no adjustment for. I crawled below and watched the bodies move (with the bike off) as my wife ran the throttle, and I could see a stopper screw where the spring loaded plates stop against.

So looking at the top of the bodies, I saw a rubber cap covering a 10mm screw. By backing out the left throttle body screw, I was able to bring my Twinmax needle to center, which started out way to the right. I gotta believe that is probably the way to adjust the idle, you can take a look and verify if it looks right to you. My idle immediately smoothened out.

Here's a picture of the screw, it has some blue silicone looking goober on it that held the rubber cap on, or maybe it is blue locktite. In either event, it was easy to adjust.




I just took the bike out and it runs smoother than ever. And it quit shaking at idle, which is why I was wanting to do this work in the first place.

I'm pumped! Thanks for all the good info you provide, it's easy to follow and understand.

I'm off for an afternoon ride!

Rich

Idle screw

Rich i have a 05 12rt and on my first tune up i performed myself at 18000 i looked at a tb sync for an 04 1150 and i assumed that this screw with the blue thread locker on it was the same brass screw used on earlier models to adjust idle speed, well after 3 weeks and 850 dollars and 2 new throtle bodies later, i learned the hard way not to touch these screws, i to obtained a better and smother idle but the following morning the bike was difficult to start, and would not hold an idle for 15-30 seconds, once warmed up it ran ok but stumbled on throttle opening, the dealer thought he could take the tbs off another new bike and measure the clearence of the opening, this proved impossible for the dealer, in the end bmwna service rep advised that these are set at the factory on a bench flow meter and matched at the factory, since that time i purchased jims video and no longer worry about the idle, please be carfull adjusting these screws, as a point of shame i was told by the bmw rep that i was the first person to screw up there tbs by adjusting this screw.

Rich,

That is the screw that is IMHO never to be touched. Idle sync is done by the stepper motors that Jim shows unplugged. Apparently the dealer can tweak this sync with the GT1 computer.. the blue screw is the base setting for the throttle plates - and is set at the factory by putting the throttle bodies on a flow bench to match the closed positions.

You guys have me concerned now. Good thing I kept an eye on how far I turned it, if that matters.

In my tiny mind I would think that you would adjust the plates for a syncronized idle with the stepper motors disconnected, but it appears I'm incorrect by your statements.

I did a cold start this morning and went for a nice ride. It fired right up and idled great. The bike is still running smoother than ever, and even when I started it cold it didn't shake like it has been before I did any tweaking. The Givi windscreen that normally fluttered wildly now sits almost perfectly still.

So the big question: Do I put the screw back to where it was? My plan is to leave it as is, as long as it runs good. (I just ran out to the garage and started the bike again, it idles like a dream.)

What do you guys think? And thanks for your comments.

HI Rich,

I would make a note of how much you moved the screw, then ride it as is for a while and see if you have any rideability issues with it. Since you know the original setting, you should be able to get it back close enough that the stepper motors can ajust for it.

I suspect you wont, though I agree with Don. The stepper motors will keep the bike close to tune, even if the Twinmax isn't showing it. However, I am very curious if the screw you adjusted moved the butterfly valve? If it did, that would be a bad thing, because the stepper motors will have to try to compensate.

I'll check into this when I get a chance, and see if I can determine for sure what the function of the screw is?

Thanks for the input,

Jim

PS I just don't get what happened with Carl's bike. I can't see how he irreperably damaged the TB's, nor why a competant tech could not reset them?

Rich said:

You guys have me concerned now. Good thing I kept an eye on how far I turned it, if that matters.

In my tiny mind I would think that you would adjust the plates for a syncronized idle with the stepper motors disconnected, but it appears I'm incorrect by your statements.

I did a cold start this morning and went for a nice ride. It fired right up and idled great. The bike is still running smoother than ever, and even when I started it cold it didn't shake like it has been before I did any tweaking. The Givi windscreen that normally fluttered wildly now sits almost perfectly still.

So the big question: Do I put the screw back to where it was? My plan is to leave it as is, as long as it runs good. (I just ran out to the garage and started the bike again, it idles like a dream.)

What do you guys think? And thanks for your comments.

Click to expand...

It sounds like Carl went to cranking on both sides, which probably got everything out of wack. He can add details if he reads this. Hard to believe it would require new bodies, you would think someone could put them back to specs.

It appears to me that the screws are the close stops for the plates. You can see a little ear on the plates that actually close and rest against the screws. I actually backed off the left side screw about 90 degrees, letting the plate close a hair more. That's my take on it. My adjustment didn't affect the reading at higher RPM's at all.

I will take your advice and ride it, I have a 4 day ride planned in the Black Hills this weekend. I should know by then if something is amiss.

I agree, and it sounds like a reasonable plan!

Keep us informed as to what happens!

Jim

Rich said:

It sounds like Carl went to cranking on both sides, which probably got everything out of wack. He can add details if he reads this. Hard to believe it would require new bodies, you would think someone could put them back to specs.

It appears to me that the screws are the close stops for the plates. You can see a little ear on the plates that actually close and rest against the screws. I actually backed off the left side screw about 90 degrees, letting the plate close a hair more. That's my take on it. My adjustment didn't affect the reading at higher RPM's at all.

I will take your advice and ride it, I have a 4 day ride planned in the Black Hills this weekend. I should know by then if something is amiss.

Click to expand...

Several cold starts, a short warm-up idle, and a 1000 miles later, all is well.

Rich said:

Several cold starts, a short warm-up idle, and a 1000 miles later, all is well.

Click to expand...

Sweet!

Something I noticed on Tina's bike when I did the 24K last week is that hers has no covers on them like the GS. Probably because they are under a fairing piece.

My friend Kermit is going to do his 36K this weekend, and has complained about his idle being rough. I told him about this, and he will likely give it a try, keeping very close tabs on exactly how much he moves the screw.

Thanks for the update!

Jim

With the stepper motors disconnected what should the idle RPMs be?
I'm using a Synchromate2 and it also tells you the RPMs.

I reckon 1100 RPM +/-50

Burnszilla said:

With the stepper motors disconnected what should the idle RPMs be?
I'm using a Synchromate2 and it also tells you the RPMs.

Click to expand...

The stepper motors don't effect the idle rpm. It should be around 1100 +- 50.

Jim

The stepper motors don't effect the idle rpm. It should be around 1100 +- 50

The stepper motors don't effect the idle rpm. It should be around 1100 +- 50



Forgive please, just what do the stepper motors do? Or control?
max

maxscycle said:

The stepper motors don't effect the idle rpm. It should be around 1100 +- 50



Forgive please, just what do the stepper motors do? Or control?
max

Click to expand...

Unless a dealer tells us, and none seem willing to do so, we are only guessing, but since several tests at idle with the stepper motors connected, then disconnected, have shown absolutely no changes, most of us are guessing it controls off idle transitions, and possibly idle balance, but not idle speed apparently.

Jim

JimVonBaden1 said:

Unless a dealer tells us, and none seem willing to do so, we are only guessing, but since several tests at idle with the stepper motors connected, then disconnected, have shown absolutely no changes, most of us are guessing it controls off idle transitions, and possibly idle balance, but not idle speed apparently.

Jim

Click to expand...

This is a case where I would have beg to disagree.

The stepper functions should be identical to the function of the BBS (Big-Brass-Screw) on oilheads and the fast-idle control.

The BBS set the idle throttle body balance AND the idle speed. The butterflys are set to a default position at the factory and are not to be field adjusted. The steppers control idle speed - especially duing cold start, just like the fast idle lever did on the oilheads.. they allow more air around the butterfly to maintain idle speed on a cold engine.

It's unclear to me what "off idle transitions" are..

For a test of the stepper functions.. stop the engine after idling when hot. Disconnect the steppers - then let it cool overnight and try starting it. Bet it won't idle happily when cold.

Disconnecting and reconnecting at a single temp (a warm engine for instance) won't show a difference between connected and disconnected - since the system doesn't have to compensate for temperature of the engine.

Points well taken Don, and they make sense.

I will test the theories out on the next TB sync.

Just a case in point though, I did disconnect the Stepper Motors with the engine cold, and warmed it up on one bike, TB off slightly. Plugged it in and it was still off. But only once, so hardly definitive, and the bike didn't idle well until it was warmed up. It is also possible that the stepper motors only function is to act like a choke, electronicly. So far either the dealers don't know, or they are not saying.

As for not adjusting the butterfly set screws, I would normally agree on an oilhead, but maybe not necessarily on the Hexhead, this remains to be seen as well, as there is some evidence that this is a viable way of setting the balance at idle.

NOTE: I am NOT recommending anyone move the butterfly screw, just not convinced it is going to cause the same issues it caused on the Oilheads!

Good discussion, and we are all learning as we go.

Jim

deilenberger said:

This is a case where I would have beg to disagree.

The stepper functions should be identical to the function of the BBS (Big-Brass-Screw) on oilheads and the fast-idle control.

The BBS set the idle throttle body balance AND the idle speed. The butterflys are set to a default position at the factory and are not to be field adjusted. The steppers control idle speed - especially duing cold start, just like the fast idle lever did on the oilheads.. they allow more air around the butterfly to maintain idle speed on a cold engine.

It's unclear to me what "off idle transitions" are..

For a test of the stepper functions.. stop the engine after idling when hot. Disconnect the steppers - then let it cool overnight and try starting it. Bet it won't idle happily when cold.

Disconnecting and reconnecting at a single temp (a warm engine for instance) won't show a difference between connected and disconnected - since the system doesn't have to compensate for temperature of the engine.

Click to expand...

I'll keep watching this thread for further updates as it moves along.

As far as the what appears to be an unsyncronized idle, has anybody had this problem and actually had it smoothened out by the dealer adjusting the stepper motors the way Don described?

I'm just curious if it is a normal everyday problem?

I'm with Jim and Don both, don't go cranking on the screws just yet. I may have gotten lucky, and I'd sure hate for someone to really mess up something that maybe just shouldn't be messed with.

The stepper motors do function like the BBS' did. Idle speed AND balance.

Idle speed: try this: while your bike is running, unplug an injector. What happens? What happens on an R11xx?

Balance: self-ex and I think it's pretty clear.

Bottom line: there are no user adjustments for either one so it's pretty logical that the computer deals with it. It does this by reading the crank speed on each firing stroke and adjusts each side (fuel and air) as needed to maintain the right RPM and the right balance between the left firing strokes and the right ones. It knows which is firing by reading the cam sensor on the right-side cam, and it monitors the engine speed by the HES which reads the teeth on the front balance shaft drive gear.

As for the sealed throttle stops, IMO just like the R11xx you can make an adjustment that works with the ECU's assumptions or you can make one that makes it harder for the ECU to adjust. Sounds like Rich did the former and Carl did the latter.

All that the user can do is adjust the cable synch (really, this is all the dealer does also but he does it without the steppers interfering). I don't know if the steppers will try to smooth out the part-throttle operation or not.

AntonLargiader said:

The stepper motors do function like the BBS' did. Idle speed AND balance.

Idle speed: try this: while your bike is running, unplug an injector. What happens? What happens on an R11xx?

Anton, I'm not sure what you mean by this? On the R1100/1150, the idle goes to crap, and it runs on one cylinder. Obviously that will also happen on the R1200, but what does that have to do with the stepper motors?

Balance: self-ex and I think it's pretty clear.

Bottom line: there are no user adjustments for either one so it's pretty logical that the computer deals with it. It does this by reading the crank speed on each firing stroke and adjusts each side (fuel and air) as needed to maintain the right RPM and the right balance between the left firing strokes and the right ones. It knows which is firing by reading the cam sensor on the right-side cam, and it monitors the engine speed by the HES which reads the teeth on the front balance shaft drive gear.

As for the sealed throttle stops, IMO just like the R11xx you can make an adjustment that works with the ECU's assumptions or you can make one that makes it harder for the ECU to adjust. Sounds like Rich did the former and Carl did the latter.

All that the user can do is adjust the cable synch (really, this is all the dealer does also but he does it without the steppers interfering). I don't know if the steppers will try to smooth out the part-throttle operation or not.

Click to expand...

So, essentially, you are saying I have been doing it right all along?

Thanks Anton, I know you have occasional access to the GT1, so I figure you have an insite. From what you just said, the GT1 does NOT adjust anything at idle, the bikes computer does it all by itself via the stepper motors and the spark timing? Or was it just the stepper motors?

Thanks again,

Jim

Dredging up an old thread -- please bear with me, as I didn't see another subsequent thread on the same subject.

I'm curious whether in the 1 1/2 years since the last post in this thread, anyone has gained any more experience with adjusting the "thou-shall-not-adjust-me" throttle stop screws.

I expect my new '09 RT will smooth out a bit as it breaks in, but as of today (~1100 mi.) it is idling a bit rougher than I would expect (yes, I know -- "it's a boxer, it's gonna rock and roll at idle" ) My expectation though, based on the 4 boxers currently in the garage, is that the counter-balanced R12 should idle smoother than my wife's R1150GS.

So, when/if I ever get any free time, I intend to throw the TwinMax on the bike to get a current baseline reading at idle for future reference. Then, at some point in the future, if no one has had any further problems with tweaking the stop screws, the curious ex-engineer in me will probably start fiddling with the screws to see whether an adjustment helps smooth things out, or whether, even if adjusted, the steppers cancel out the throttle stop adjustments anyway when they are reconnected.

Also, before I do so, I will seek out a better understanding of the stepper motors' specific function -- as I currently understand it, the stepper motors control the air bypass around the throttle plate for *both* idle speed and cold start high idle control. I suspect they also are coordinated with the fuel injection amount in response to the closed-loop O2 sensors for emissions purposes (once the O2 sensors are up to operating temp).

FWIW, at the moment at least, I'm guessing that the the reason the stop screw adjustment is "critical" is that the stepper motors have only a limited command authority, and therefore the throttle bodies have to be set up in a relatively narrow range of adjustment to ensure the stepper motors can exercise bypass control over the entire intended operating range. Accordingly, if they are adjusted enough that one or both of them are out of the "acceptable" range and the stepper motor can no longer provide enough bypass flow to meet the engines requirements, the engine runs poorly.

If that is correct, I'm guessing that the stop screw adjustments are not so much "critical," but simply intolerant of large movements away from the factory settings -- settings made on a flow bench to a tolerance of "good enough" for correct operation with the stepper motors, but not necessarily "perfectly" matched to obtain the smoothest idle. In other words, I suspect that a bit of fine tuning to improve balance should be well tolerated as long as the throttle plates remain within the operating range of the stepper motors.

Well, that should stir up things a bit Seriously, I'd appreciate further thoughts/debates/suggestions from the Collective. Thanks!

Mark