Throttel body throttle shaft/cam install procedure_

[dirtrider]

 

I  m-i-g-h-t have a possible work around for a home install without a GS-911 and a fiddly/feely/subjective procedure.

 

Caution: this is a work in progress but I thought I would toss it out here early  to be questioned/debated/tweaked/thought about.

 

My 1200 throttle bodies were just laying on my workbench waiting for new Bing shafts/cams to arrive so I decided to do a little repeatability testing.

These were non-molested original throttle bodies with intact Bing factory paint on the base idle screws.

 

First, I completely cleaned the throttle bores & throttle plates so ACCURATE measurements could be taken using thin feeler gauge stock.   (be real careful here to not get cleaning solvent into the stepper connector pin area or TPS pin area)—
Or just remove the steppers then  mark & remove the TPS.  Problem with removing the TPS before cleaning is that allows washing the TPS position marking paint off, or washing the  position locating marks off. I left both the steppers & TPS on but covered the pin areas & was careful to not saturate the steppers or TPS with solvent.

 

Next, carefully & with precision I  marked the TPS position to the L/H  body housing. (this is an important step). I used some thick white marking paint, then when dry used an X-acto knife to scribe a  thin precision line across the TPS housing onto the throttle body on both sides of the TPS. (be accurate as possible with this step)

 

 

On the R/H throttle body  I carefully pried the outer throttle shaft cover cap off. I used a very small achilles heel to evenly work it off by continually working it up & off as I continually worked around it.  (the cap was somewhat difficult to remove without damage)

 

 

Both the TPS (L/H) side TB and the shaft cover cap (R/H) side TB  MUST be removed to access the retaining circlips under them (shafts are held in place by external circlips).  I didn’t remove the circlips just yet (just getting the access to them out of the way so I didn’t have to interrupt the shaft measurement & other work continuity).  

 

 

On to the measurements & pre-work/post-work noted below___

 

I first inserted .0015” feeler stock between the top of  throttle plate & the throttle bore, I then did the same on the very bottom of the throttle plate.  (perfectly centered & straight). So had a .0015” feeler stock at both the very top & at very bottom of the closed throttle plate.

That allowed the throttle plate to fully close on the .0015" feeler stock. With the .0015” feeler stock the TB idle stop lever j-u-s-t contacted the idle stop screw with no gap.

 

Next, I then did the same thing, only this time used .002" thick feeler stock.  This allowed the throttle plate to close firmly on the .002” feeler stock BUT, it prevented the  TB idle stop lever from fully contacting the idle stop screw.

 

 

I then used different thickness feeler stock to measure the stop lever to base idle screw gap (it was right at .0015” stop arm to screw tip).

 

 

I then measured the other side throttle body  & it measured out to the exact same numbers (good, looks repeatable between sides & sort of tells me that Bing set them to the same base idle screw settings on both TB’s).

On these (my set) of throttle bodies it looks like Bing set the original factory throttle plate air gap to around .0015” (maybe slightly more but not much)  but not nearly as much as .002".

 

I then blued & scribe-marked the factory throttle plates along the edge of the throttle shaft  for position (mainly this is for accurate plate clocking position at re-install).

 

 

I then unhooked both return springs,  then removed the shaft retention circlip & plastic washer, then removed the throttle plate & throttle shaft from the first throttle body. (caution: don’t lose the plastic outer hat-shaped collar that is under the shaft lever) 

 

Now for the reassembly/repeatability test___

 

I re-installed the original throttle shaft & throttle plate being extra careful to match the throttle plate scribe marks up to match the throttle shaft sides (this re-sets throttle plate ‘clocking' back to  where they were). Then I very lightly tightened the throttle plate screws (very lightly).

 

Once all above was verified I reinserted the .002" feeler stock between the top & bottom of the throttle plate to throttle bore & allowed the factory springs to close the throttle plate (I then backed the throttle plate screws out slightly (to allow throttle plate to self center in the throttle bore against the top & bottom .002” feeler stock. I then re-checked that the throttle plate  scribed lines were still aligned with the throttle shaft edges (important). Then fully tightened the throttle plate  screws. Then re-checked that the scribe lines still line up EXACTLY.

 

I then removed the .002”feeler stock & verified that I still had the needed lateral movement in the throttle shaft with throttle plate open a little. (also verified that the square edges on throttle shaft align somewhat with the insides of the throttle bore.

 

 
I then opened & closed the throttle plate by using the cam to open/close it a few times  & even allowed it to snap closed a couple of times.

I then reinstalled the .002” feeler stock between the top & bottom of the throttle plate & throttle bore then allowed the throttle plate to close on the .002” feeler stock.

 

I then re-measured the gap between the base idle screw & the stop lever (it was back to the pre-work gap of .0015”.

This tells me the process can be repetitive if care is taken in the feeler stock placement & throttle plate clocking & alignment.

The above was just the preliminary to SEE if I could get the stock throttle plate & stock throttle shaft/cam back to where it was from the factory.—I would say that the repeatability test was a success.

 

Note: the above was only re-installing the original shaft/cam not the new shaft/cam -- but the new shaft/cam install used the same basic procedure, only I had to adjust the base idle screws to regain the .0015" stop lever to base idle screw gap.

 

I will add the new shaft/cam install  procedure as I define it.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

[greiffster]

DR,

I finally got around this weekend to swapping out my new Bing cams/shafts with your procedure.  Here is what I found.

 

Prior to the TB removal, I did check and note my stepper counts and cross balance in order to compare it after the new cams were installed.  I was out of balance some at 3000 rpm, but idle was good/very close.  Actually, I was a little surprised as my balance has been pretty steady on this bike.  I left it alone.

 

I did the left TB first and followed your procedure closely.  I second the idea of taking lots pictures of the TB prior to removal and prior to disassembly.  The electrical wiring runs on different sides of the throttle cable on either TB side (at least on the GS).  Having a couple photos can help avoid frustration.  Also, I would take special note of the orientation and hook points of the springs on the TB.  Finally, regarding the circle torsion spring, make sure that thing is routed correctly inside the white washer guides (for lack of a better description).  It can jump out of those guides easily during assembly.

 

So, on the left TB, using the 0015" feelers at top and bottom, the idle screw was still on the stop, but close.  But, using the 0020", I found that screw had come off the stop about the predicted 0015".  Now, it does get a bit tricky, because you can easily get different gaps depending on whether or not you let the throttle plates snap shut, gently close, or even apply a light amount of pressure with your finger on the plate itself to "set" the closure consistently.  I chose the latter method and found I could consistently get the same gap results.  I also used a very good led flashlight and tried to get a good visual of the ring of light around the throttle plates as it sat on the stop.

 

Removal and installation of the new cam/shaft was pretty straight forward.  I did scribe a good mark on the TPS, but the two screws holding it to the TB just re-aligned itself almost perfect when I screwed it back down.  There just doesn't seem to be much play in it?  Definitely, scribe some good sharpie marks on the throttle plate.  It sure helps as there is a lot of play in the holes of the plate.  Upon installation and centering of the plate, it was clear with my flashlight that I had to much gap.  With the 0020" feelers, the screw was just on the stop.  I turned my idle screw out about 180 degrees or half turn until I was back to a consistently testing 0015”.

 

The right TB was almost identical to the left upon removal.  I had the same 0015” with the 0020” feelers prior to disassembly.  Almost scary close.  The TB metal cap at the end of the shaft was stubborn to come off.  I have a couple of small pry bars similar to your picture and just couldn’t get enough bite on the lip to pry them off.  I laid the TB in an open vise so the cap was pointing down and used a sharp chisel and small hammer to tap it off.  That seemed to work better.  After assembly of the new cam/shaft, I had about a 0060-0070” gap at the idle screw.  Ultimately, I turned the screw in just over a full turn to get back to 0015”.  Maybe 370 degrees.

 

The bike runs the same. And the stepper values, idle rpm, and cross balance were basically the same after re-assembly.  I’ll report back if I notice any changes, but I did adjust my balance at the right side to take out the original unbalance at around 3000rpm.

 

A few take-aways.  First, if I ever see the guy who decided that the Oetiker style clamps were a good idea for the air intakes and TBs, I’ll probably punch him in the face.  I have two styles on my bike with the ones at the air box being different and the most difficult (you can get the TBs off without removing the clamp at the air box, but it is more difficult).

 

Just out of curiosity, I unscrewed the cam from the new shaft.  It is a still a snug fit, but not pressed on.  Perhaps this is part of a fix?  Maybe the pressing of the cam end and subsequent stretching of the metal also imparted some tensile stress to the plastic and over time, contributed to the fracture?  I’m sure Bing will tell us if we ask.

   

Upon further inspection of my old cams/shaft, they were both cracked on the back or insides as well, but, in different radial spots than on the front side.  I find this strange.  The one at the right TB had a jagged double stress crack.  I will note that even with the cracks, a total failure doesn’t see imminent.  The plastic cams still feel very firmly bonded to the metal.  I assume this is why we are seeing many cracked cams of these vintage bikes, but not too many failures.

 

 

[dirtrider]

1 hour ago, greiffster said:

DR,

Just out of curiosity, I unscrewed the cam from the new shaft.  It is a still a snug fit, but not pressed on.  Perhaps this is part of a fix?  Maybe the pressing of the cam end and subsequent stretching of the metal also imparted some tensile stress to the plastic and over time, contributed to the fracture?  I’m sure Bing will tell us if we ask.

   

 

 

 

 

Morning Mike

 

Thanks for the update, please keep us posted on how it works out long-term? I will add your comments into the final procedure plus any other comments  that show up in this thread as more cams  are replaced by other riders.

 

Does the procedure need any other tweaking as far as missed steps, or difficult to understand areas?????

 

I have done (2 bikes) now using 'the' procedure (3rd one coming right up) & so far it has worked out good. 

 

I did call Bing on those screws & it wasn't the answer we were hoping for. Seems that Bing in Europe won't send the shafts & cams already assembled so Bing USA needs to assemble them here (therefore the screws) are used to pull the new cams onto the shafts & keep retain them there.

 

Added:  I guess that also confirms my fears that a rider can't 'JUST' install the shafts/cams without adjusting the base idle screws & have them be even close.

[greiffster]

The procedure is pretty straight forward once you get started.  Having the TB in hand clears up any of the text that may otherwise be tricky to understand.  I would stress that point of visually inspecting the ring of light around the throttle plate, if only for a backup measurement.  I would bet I could come pretty close just on the visual.  I find about a half turn on the idle screw to be apparent with just a good light.

 

I don't think that Bing could manufacture the shafts/cams to tight enough tolerance to say 0020-0030" at the idle stop relative to the "plane" of the throttle plate.  First, you've got the rotation of the "square" edge of the cam fitting relative to the throttle plane (maybe it's zero, but it doesn't really matter)  How do you do that with limited tolerance to not have an amplified effect further away from the radius of the shaft (ie the stop).  And then the metal bent portion of the stop??  What is the tolerance of the machine bending that thing?  I'm actually quite surprised that they are as close as they are.

 

My big question is what affect does the bike feel if the screw is out/in by a certain amount?  IOW, how close is good enough?  My cams were within about a full turn on the screw (one was half).  Maybe I got two good cam/shaft replacements? Maybe they are all within that tolerance?  But what does one turn on the idle screw really do to the bike?

[greiffster]

3 hours ago, dirtrider said:

I did call Bing on those screws & it wasn't the answer we were hoping for. Seems that Bing in Europe won't send the shafts & cams already assembled so Bing USA needs to assemble them here (therefore the screws) are used to pull the new cams onto the shafts & keep retain them there.

 

 

 

That screams BS to me. 

[dirtrider]

4 minutes ago, greiffster said:

 

 

My big question is what affect does a the bike feel if the screw is out/in by a certain amount?  IOW, how close is good enough?  My cams were within about a full turn on the screw (one was half).  Maybe I got two good cam/shaft replacements? Maybe they are all within that tolerance?  But what does one turn on the idle screw really do to the bike?

 

 

Afternoon Mike

 

There has to be some wiggle room here but the base idle screws add a fixed amount of air then the steppers control what is needed (+/-) on top of the base air flow. (steppers can't go any lower than base idle screw settings allow)

 

SO__ the base idle air flow (screw position) must allow enough base flow  to allow the Steppers to go to their fixed cold-engine starting position (based on engine temp, & other sensor inputs) so the engine has enough cold start air flow to allow quick engine starting in any conditions or oil thickness & remain running long enough for the steppers to start reacting & control engine RPM's.

 

On the other end the base air flow must be low enough to allow the engine idle to drop low enough at hot-engine, thin oil, high atmospheric pressure to it can get to low RPM command (plus not have the steppers bottomed out at 0 counts).  

[dirtrider]

5 minutes ago, greiffster said:

 

That screams BS to me. 

 

 

Afternoon Mike

 

Actually it doesn't to me as I was thinking of buying only the cams & that was going to be the way that I was going to install/retain the new cams on the original shafts.

 

In fact now that I have a couple of sets of shafts with broken cams I am probably going to start installing new cams on those shafts then rotate those into the next bike that needs cams replaced.   

[greiffster]

Update:

After a good road trip and 800+ miles after the cam/shaft replacement, I cannot say I've noticed any difference in performance. The idle is the same steady and smooth 1150rpm-ish as it was prior to the swap.  The bike starts the same.  I did a small adjustment to the TB balance to take out an off idle (around 3000rpm) imbalance.  But, I assume that the base idle adjustment wouldn't have much effect off idle that far anyway.  I'm pretty confident this method is going to yield consistently good results.

[dirtrider]

7 hours ago, greiffster said:

Update:

After a good road trip and 800+ miles after the cam/shaft replacement, I cannot say I've noticed any difference in performance. The idle is the same steady and smooth 1150rpm-ish as it was prior to the swap.  The bike starts the same.  I did a small adjustment to the TB balance to take out an off idle (around 3000rpm) imbalance.  But, I assume that the base idle adjustment wouldn't have much effect off idle that far anyway.  I'm pretty confident this method is going to yield consistently good results.

 

 

Morning Mike

 

Thanks for the follow up (sounds like your bike is working good).

 

The two 1200 bikes that I have done using that procedure have also worked out good with no detectable before/after differences.

 

I have a 3rd & 4th bike to do with the 3rd coming up shortly & the 4th later this spring. (probably more as more riders inspect their 1200 TB cams)

 

I hope this procedure pans out long term as there seems to be a LOT of 1200 bikes now turning up with cracked TB cams.   

[SHIMHEAD]

Hello Dirtrider,

     Thought I would add my 2 cents here. Assuming good mechanical engine condition, no intake air leaks, etc. Use stepper counts as a baseline for idle air flow combined stepper passage/throttle stop adjustment. Post cam install, do a live stop adjustment to achieve the same stepper counts as before. Theoretically this should achieve the same base idle airflow around the throttle plate well within the acceptable range of factory adjustment?? Looking for your thoughts. Maybe try it this way and compare to the careful measure/record/reset to measurement process. Of course clean throttle bodies and stepper passages, as well as fully functional steppers would be pre-requisites.

[dirtrider]

2 minutes ago, SHIMHEAD said:

Hello Dirtrider,

     Thought I would add my 2 cents here. Assuming good mechanical engine condition, no intake air leaks, etc. Use stepper counts as a baseline for idle air flow combined stepper passage/throttle stop adjustment. Post cam install, do a live stop adjustment to achieve the same stepper counts as before. Theoretically this should achieve the same base idle airflow around the throttle plate well within the acceptable range of factory adjustment?? Looking for your thoughts. Maybe try it this way and compare to the careful measure/record/reset to measurement process. Of course clean throttle bodies and stepper passages, as well as fully functional steppers would be pre-requisites.

 

 

Afternoon SHIMHEAD

 

That is basically the way I did the first  ones a while back,  problem is that is way more complicated & fiddly  than it sounds at first thought. That is also what drove me to try & find a simpler way that even a cave man can do it.

 

Then if the TB's are cleaned during the throttle shaft/cam work that can skew the baseline numbers as being totally useful.

 

That way works as I have done it that way but I was really looking for a much simpler way that could be done without the need for GS-911, or need of a lot of post work fiddly adjustments.

 

 

 

 

[Mike T]

Replaced my Throttle Body cams yesterday. Procedure very helpful so thanks very much for that. The hardest part was getting the aluminum cap off the right TB. I ended up using Mike's suggestion of a small coal chisel and small hammer to tap the cap off. It just caught the edge. Be careful when putting the TB in a vice. Very soft metal that will get marked up easily. Tip: when removing the TB's from the bike there is a stainless clip that releases the throttle cables from the black plastic TB housing so no need to loosen the lock nut on the cable (like I did).   Another Tip: I used a large paper clip to reattach the round cam spring end piece . You can easily grab the bent end to lift it up back on the new cam bracket. 

 

Both of my original TB's butterfly valves showed an equal amount of light all the way around them inside the TB when you shined a light behind them.  Left and Right looked to be the same and had a .0015 gap top and bottom as predicted. Very important to mark the brass butterfly valves with sharpie to show where the cam post is attached to them (as indicated with photos above.) I ended up making no adjustments to either stop screw. Did a TB sync using a manometer. The idle was off from side to side (not sure if this was true before). I decided to leave it as is since it idled smoothly and was at 1150 rpms. I did have to adjust the right side cable at 1800RPM to sync the the TBs using a GS-911. Took a short test ride and bike runs better than before with no issues noted.  

 

Thanks Guys for all the excellent info!

 

BTW, both cams had one or two cracks on outside of the cam and the Left TB had a crack on the inside as well. Everything still very tight and probably would have lasted a quite a while but better to fix at my convenience without paying for towing and have peace of mind. 

 

If anyone near Boulder, CO needs help with replacing theirs I'd be happy to assist. 

 

Cheers

 

Mike 

 

 

[dirtrider]

13 hours ago, Mike T said:

Replaced my Throttle Body cams yesterday. Procedure very helpful so thanks very much for that. The hardest part was getting the aluminum cap off the right TB. I ended up using Mike's suggestion of a small coal chisel and small hammer to tap the cap off. It just caught the edge. Be careful when putting the TB in a vice. Very soft metal that will get marked up easily. Tip: when removing the TB's from the bike there is a stainless clip that releases the throttle cables from the black plastic TB housing so no need to loosen the lock nut on the cable (like I did).   Another Tip: I used a large paper clip to reattach the round cam spring end piece . You can easily grab the bent end to lift it up back on the new cam bracket. 

 

Both of my original TB's butterfly valves showed an equal amount of light all the way around them inside the TB when you shined a light behind them.  Left and Right looked to be the same and had a .0015 gap top and bottom as predicted. Very important to mark the brass butterfly valves with sharpie to show where the cam post is attached to them (as indicated with photos above.) I ended up making no adjustments to either stop screw. Did a TB sync using a manometer. The idle was off from side to side (not sure if this was true before). I decided to leave it as is since it idled smoothly and was at 1150 rpms. I did have to adjust the right side cable at 1800RPM to sync the the TBs using a GS-911. Took a short test ride and bike runs better than before with no issues noted.  

 

 

Morning Mike

 

Thanks for the feedback after replacing your cams. This is the type of feedback that we are looking for.

 

Removing that cap does seem to be a pain in a$$, I have done a couple more since I posted the above & like yours, seem to be running/working great.

 

I have been able to get all the caps off using my small Achilles heel (sp) & working around  the cap but not everybody has a small achilleas heel  in their tool kit (so the chisel option should probably be added to the procedure).

 

On clamping the TB's into a vise, I usually use small pieces of 1/4" thick plywood  on each end of the TB (inlet & outlet ends)  then clamp them in the vise longways (they seem quite strong in that direction so not much chance of crushing the TB) but it does take a slightly larger vise to get them to fit that direction.

 

Please post a long term follow up after riding the bike for a month or so.

 

 

[lkraus]

7 minutes ago, dirtrider said:

...using my small achilleas heel & working around  the cap but not everybody has a small achilleas heel  in their tool kit...

OK, Google was no help. 

What is an achilleas heel?

[dirtrider]

1 hour ago, lkraus said:

OK, Google was no help. 

What is an achilleas heel?

 

 

Morning Larry

 

It should read  "Achilles heel"   (at least it did until my spell check militated it)  ---I'll fix that now!

 

This little devil (picture only shows the lower part of it  but I'm sure that you have seen them before). I don't even know what the technical  name is  but we have been calling them Achilles heels  forever.

 

Put  ----      Achilles heel pry bar           --- into Google

 

[lkraus]

Got it. I think I have a couple bars like that in a box lot I picked up at an auction.

 

I'll attribute "militated" to your mutilating spell checker, too. 

[dirtrider]

2 hours ago, lkraus said:

Got it. I think I have a couple bars like that in a box lot I picked up at an auction.

 

I'll attribute "militated" to your mutilating spell checker, too. 

 

Afternoon Larry

 

That was an on-purpose but I guess it wasn't funny? 

[Bigfish]

DR, I am about to attempt upgrading to the Machined Cam part ( http://www.beemerbits.com/catalog/product_info.php?products_id=856) here.

I have been studying this thread intently and was wondering about my particular retrofit to these new Cams.

Do I need to remove the Cam Shaft in order to fit these Machined Parts onto the Throttle Bodies?

Upon inspection of my 09 RT with 32,000 miles, both sides are showing cracks in the plastic cam.

When I get the TB off the bike, can't I just chip off the cracking plastic piece then slide the new Machined Aluminum Cam Part on.

Wouldn't this avoid all the marking and measuring to put the flapper and shafts back in the same exact position. Or is all that work to remove the shaft for cleaning up the bore?

 

Thanks!

[dirtrider]

3 hours ago, Bigfish said:

DR, I am about to attempt upgrading to the Machined Cam part ( http://www.beemerbits.com/catalog/product_info.php?products_id=856) here.

I have been studying this thread intently and was wondering about my particular retrofit to these new Cams.

Do I need to remove the Cam Shaft in order to fit these Machined Parts onto the Throttle Bodies?

Upon inspection of my 09 RT with 32,000 miles, both sides are showing cracks in the plastic cam.

When I get the TB off the bike, can't I just chip off the cracking plastic piece then slide the new Machined Aluminum Cam Part on.

Wouldn't this avoid all the marking and measuring to put the flapper and shafts back in the same exact position. Or is all that work to remove the shaft for cleaning up the bore?

 

Thanks!

Morning Bigfish

 

You can install the Beemerbits cams without removing the shafts or doing most of the above. 

 

See instructions here____  https://docs.google.com/document/d/1VCMTVPJNxGEUfM_UVJ3B8-GrmQgj6yffb42OQHb1UAw/edit

[bobde1234]

Here’s how I removed the metal cap without marring the throttle body or the cap. You’ll need 4 items:

An m25 external snap ring

A metal washer with 2 flats ground on it (I used 7/8” Id, and pretty thick. 

A slide hammer that has a couple external claws. 
snap ring pliers
 

I put the TB in a vice with wood soft jaws, with the metal cap facing up. I taped the exposed TB just in case something might scratch it. Then I put the washer over the cap, followed by the snap ring in the recess directly under the metal cap. The snap ring had a great seat on the edge of the metal cap almost 360°. I hooked my slide hammer claws on the flats on the washer so it wouldn’t slip and gently tapped up. It didn’t require much time or force and the cap easily popped off. It took me more time at the hardware store than to get this part off. I hope this method helps someone else! 

[bobde1234]

I measured my throttle bodies using the technique of this thread (shimming the throttle plate TP with 2 equal feeler gages and measuring the Base Index Screw BIS gap) and here are my numbers.

 

For reference:

My bike is ‘07 r12r and my TB are 77/47.

 

I didn’t look at the idle stepper motors count before taking the TB off, so I don’t have that data. 

 

 The blue paint on the base idle screws looks original and untouched (even used magnification).  
 

When I placed shims on the top and bottom of the TP, I made sure they were in the machined section and did not rest on the step/inclined machined area. 

data:

I got the same measurements for L&R TB. 
 

With 0.0015 TP shims the BIS touches the stop plate 

 

With 0.0020 TP shims the BIS touches the stop plate

 

With 0.0025 TP shims the BIS gap is 0.0025 

 

With 0.003 TP shims the BIS gap is 0.013 (I measured here just out of curiosity to see how the BIS gap would grow.

 

conclusion:

Common with a few people that posted on this thread, my left and right TB measurements are the same.

 

Not common to the other results on this thread, my measured gaps are larger. I was expecting to see a BIS gap when i shimmed  the TP out  to 0.0020, but it was still at the stop plate. It wasn’t until the next larger shim 0.0025 was the BIS off the stop plate. I don’t know how big a deal that is. 
 

I’ve studied this thread pretty carefully by now, and I have to decide which way to proceed. I bought the bing agency rebuild kit that contains Throttle plate shaft with pressed-on arm that has the BIS stop plate. While I have reservations about messing with the BIS, I think I’ll get the best TP position if I back it out and use the TB bore and a strong light (William from boxer2valve has a good video of this in a bing carb rebuild). I can record how much I’ve backed out the BIS and I know my factory TP gap to shoot for. 

 

 

 

 

 

[dirtrider]

16 minutes ago, bobde1234 said:

 

I’ve studied this thread pretty carefully by now, and I have to decide which way to proceed. I bought the bing agency rebuild kit that contains Throttle plate shaft with pressed-on arm that has the BIS stop plate. While I have reservations about messing with the BIS, I think I’ll get the best TP position if I back it out and use the TB bore and a strong light (William from boxer2valve has a good video of this in a bing carb rebuild). I can record how much I’ve backed out the BIS and I know my factory TP gap to shoot for. 

Afternoon bobde1234

 

Just keep in mind that you don't want the best throttle plate position, you want to duplicate your PRESENT throttle plate position. Especially on the L/H side as the the idle stop screw on the L/H side dictates the where the nominal TPS position is at base curb idle.

 

If you change the air flow with closed throttle that can change the nominal stepper count at idle. 

[bobde1234]

Yes I see what you are saying. In my case I want to preserve the relationship of 0.0025 shims on the throttle plate, and have 0.0025 gap on the base idle screw. When I look at the new throttle shaft assembly and the bent metal arm that forms the base idle stop, I have to wonder how close it can really be to the one I pulled out. Before I mess with the base idle screw, I should at least set it up with the 0.0025 shims and see what the base idle gap is. If it is same as before, for sure I won’t touch it. But if the relationship is off (and it could be because new shaft/arm) I might have to tweak it. I’d much prefer not to touch it. 

[dirtrider]

30 minutes ago, bobde1234 said:

Yes I see what you are saying. In my case I want to preserve the relationship of 0.0025 shims on the throttle plate, and have 0.0025 gap on the base idle screw. When I look at the new throttle shaft assembly and the bent metal arm that forms the base idle stop, I have to wonder how close it can really be to the one I pulled out. Before I mess with the base idle screw, I should at least set it up with the 0.0025 shims and see what the base idle gap is. If it is same as before, for sure I won’t touch it. But if the relationship is off (and it could be because new shaft/arm) I might have to tweak it. I’d much prefer not to touch it. 

Afternoon bobde1234

 

The good news is I have done a number of them now & so far they have all worked out good with little change in the before/after hot engine curb idle stepper counts. 

 

The important part is to really watch the throttle plate clocking, throttle shaft lateral positioning with throttle plate centered, & make darn sure the throttle plate is reinstalled in the correct TB with the top remaining at the top.     

[bobde1234]

Well good news. I replaced the throttle plate shaft on one throttle body, and didn’t have to change the base idle screw at all. I got the same shim to gap relationship. The clocking and caps all look good. The final test will be on the bike. I suppose I’ll need to do an idle stepper cal after all this. Do you know if there is a tps cal with gs911? It seems like there probably must be but I’ve never looked for it. 

[dirtrider]

10 hours ago, bobde1234 said:

Well good news. I replaced the throttle plate shaft on one throttle body, and didn’t have to at all. I got the same shim to gap relationship. The clocking and caps all look good. The final test will be on the bike. I suppose I’ll need to do an idle stepper cal after all this. Do you know if there is a tps cal with gs911? It seems like there probably must be but I’ve never looked for it. 

Morning bobde1234

 

The idle steppers (actuators) recalibrate themselves every time you turn the key on as at every key-on the fueling computer commands the idle steppers to home (seat) the pintle, then once home (zero counts) is assumed it opens the steppers to starting counts. With only 4 wire steppers the fueling computer gets no direct pintle position feedback so it only knows where the pintle is at the moment based on where it WAS last & how many + or - counts it has commanded. This only works if the system re-homes the steppers at every key on as the engine could have been shut down with the steppers in motion so they, then, could  be out of sync at next engine start up.

 

The GS-911 does have a service stepper calibration but that is basically so you can reset the steppers with engine running without turning the key-off then back-on. I use that function at times to try to see if a stepper is getting lost while riding (losing it's  actual position vs commanded position). 

 

To calibrate the TPS (force TPS relearn),  just disconnect the  battery for about 2 minutes, then turn the key on (do not start engine) then fully open & close the throttle a couple of times using the twist grip (only requires 1 full throttle open/close but I typically use 2 just to be sure it takes). This re-sets/re-teaches the TPS but also clears the fueling adaptive so your system starts with a clean fueling adaptive base. There is a GS-911 TPS cal but I seldom use it unless I want to save the learned fueling adaptives.   

 

If you didn't have to adjust the the base idle screw, then,  if doing the R/H TB no TPS relearn is required. If doing the L/H TB then a TPS re-learn is always a good idea. 

 

If you clear the fueling adaptives (always a good idea after throttle body work) you might have to ride the motorcycle for a while before it relearns it's new fueling adaptives (fueling off-sets). So give it a good ride before fully evaluating the effect of the TB service.  

 

 

[dirtrider]

More:

 

If you only did one side first then a good check of your work is to simply use the GS-911 to lock the steppers, or just use the GS-911 to monitor stepper counts & if they remain even side to side go with that, or without a GS-911 do the check right after a hot  engine start as the steppers usually remain locked together right after a hot engine start for long enough to do the testing.

 

Per the above, just put your liquid manometer on the throttle bodies (warm or hot engine) then start the engine, allow the idle to settle to a decent curb idle, then un-block the blocked manometer hose (you should block (pinch) one side off until engine stabilizes to prevent fluid getting sucked out at start-up).

 

If your cross side balance is under 3" of H2o then you are golden. If under 5" H2o then you are OK, if 6" you can live with that, if a lot over 6" then maybe re-address the base idle screws or throttle plate positions. Or ride the motorcycle for a while then recheck again.  

 

BMW actually gives you up to 25 mbar (10" H2o) variance so in reality that is the max but all I have done so far have never been over 5". 

 

Also check the above idle cross side balance, 15 mbar  (6" H2o) max,  but try to get it closer than that  if possible, with new throttle cams that might need to be adjusted as it could be off a little. 

 

 

[bobde1234]

Hi Dirtrider

 

On my previous comment, i made a typo which said “clocking and caps” , which should have said “clocking and light gaps”.  That actually makes sense. 
 

Thank you for the additional info. Is the tps re-learn you talked about applicable for hexhead (my bike). My Haynes manual (for 04-09 hexhead) says the tps sensor shouldn’t be removed, and if replaced, reset by the dealer. And I did see that you marked your tps with a paint mark and scribe line. I will have to do that. I’ve worked so far on the non-tps throttle body to start. 

[dirtrider]

34 minutes ago, bobde1234 said:

Thank you for the additional info. Is the tps re-learn you talked about applicable for hexhead (my bike). My Haynes manual (for 04-09 hexhead) says the tps sensor shouldn’t be removed, and if replaced, reset by the dealer. And I did see that you marked your tps with a paint mark and scribe line. I will have to do that. I’ve worked so far on the non-tps throttle body to start. 

Morning  bobde1234

 

Yes, the the 1200 hexhead can have the TPS taught. (look in your riders manual under battery replace).

 

I usually mark the TPS position as it in just a general habit on all vehicles that I remove/reinstall a TPS, on the hexhead it probably isn't necessary as the TPS is not mechanically adjustable other than nominal screw hole slop. 

 

 

[bobde1234]

Hi Dirtrider

 

After reading your remarks, I decided I’d pop the throttle bodies back on the bike and read the real time values for throttle valve position, and both idle actuator positions using the gs911. This is before making any changes at all to the throttle body which has the tps mounted. I see 0-100% on the tps, and both idle actuators read 204. This is with ign on but I never started the bike.
 

Then I performed a test to verify I could really reset the tps sensor. I simulated a change in base throttle adjustment  by inserting a long Bamboo bbq stick thru the throttle body. Now the throttle butterfly was held at something like 35.6% open (as read on gs911). I disconnected the battery and waited around 7 minutes. I reconnected the battery, turned ign on (but did not start), and cycled the throttle 3x from base position (as modified with my stick) to max position. Then I turned off ign and waited over a minute. I turned ign back on, and read my real time value from gs911. My base position remained 36.5%. I repeated this test a couple times, but I could never get the tps to think my modified base position was any other than 36.5%. The only thing I can think is that since my new base position is so radical it can’t be plausible, and no modification takes place. Maybe I’ll retest with a thinner obstruction.  Any thoughts on what I may have done wrong? 
 

I also had another idea, and I measured the current tps resistance (I got 1750 ohms at base position). When I replace the throttle shaft, if there is play, I can try to reproduce this resistance with the new shaft. It would be nicer for the tps to relearn, however. 

[dirtrider]

18 minutes ago, bobde1234 said:

Hi Dirtrider

 

After reading your remarks, I decided I’d pop the throttle bodies back on the bike and read the real time values for throttle valve position, and both idle actuator positions using the gs911. This is before making any changes at all to the throttle body which has the tps mounted. I see 0-100% on the tps, and both idle actuators read 204. This is with ign on but I never started the bike.
 

Then I performed a test to verify I could really reset the tps sensor. I simulated a change in base throttle adjustment  by inserting a long Bamboo bbq stick thru the throttle body. Now the throttle butterfly was held at something like 35.6% open (as read on gs911). I disconnected the battery and waited around 7 minutes. I reconnected the battery, turned ign on (but did not start), and cycled the throttle 3x from base position (as modified with my stick) to max position. Then I turned off ign and waited over a minute. I turned ign back on, and read my real time value from gs911. My base position remained 36.5%. I repeated this test a couple times, but I could never get the tps to think my modified base position was any other than 36.5%. The only thing I can think is that since my new base position is so radical it can’t be plausible, and no modification takes place. Maybe I’ll retest with a thinner obstruction.  Any thoughts on what I may have done wrong? 
 

I also had another idea, and I measured the current tps resistance (I got 1750 ohms at base position). When I replace the throttle shaft, if there is play, I can try to reproduce this resistance with the new shaft. It would be nicer for the tps to relearn, however. 

Afternoon  bobde1234

 

That 204 counts are just the commanded counts for starting. That is normal. They will usually always stay in sync until the engine is warm & certain conditions are met, a that time they go dynamic & go to independent control. It can take a long time for the steppers to go independent at times. 

 

As far as holding the TPS  throttle side open then trying a forced TPS relearn,  I haven't ever tried that. It might be so far out of expected that it won't reset, or possibly the battery wasn't disconnected long enough (try a lot longer disconnect & less forced hold-open). Also try a key-on with the battery disconnected as that can deplete the BMS-K capacitors quicker. As far as you were holding the throttle plate open it was definitely out of it's base range. 

 

I wouldn't worry about that as if you see see 0-100% TPS  then the BMS-K is happy & probably won't re-learn or re-set. 

 

[bobde1234]

Hi Dirtrider

 

i think I’ve got it figured out. I used a single thickness of blue painter tape to hold the throttle plate open, and it measured 3.5% on the gs911 (much more plausible). I turn off ign and wait till I see the gs911 stop communicating, then I turned ign back on, and the tps reading is 0%. Funny thing it will read 0-98.5%. But the key is that when ign is turned on it takes the base position as 0%. Another oddity is that if I remove the tape and close throttle, it remains at 0%. So my conclusion is that if I remove the tps and and replace it close to original, it will think the base position is 0%. Fwiw I didn’t have to disconnect the battery or cycle the throttle at all for the new 0%. 

[dirtrider]

14 minutes ago, bobde1234 said:

Hi Dirtrider

 

i think I’ve got it figured out. I used a single thickness of blue painter tape to hold the throttle plate open, and it measured 3.5% on the gs911 (much more plausible). I turn off ign and wait till I see the gs911 stop communicating, then I turned ign back on, and the tps reading is 0%. Funny thing it will read 0-98.5%. But the key is that when ign is turned on it takes the base position as 0%. Another oddity is that if I remove the tape and close throttle, it remains at 0%. So my conclusion is that if I remove the tps and and replace it close to original, it will think the base position is 0%. Fwiw I didn’t have to disconnect the battery or cycle the throttle at all for the new 0%. 

Afternoon  bobde1234

 

It's not the 0% that gets reset, it's the WOT that needs to see 100% at WOT (Wide Open Throttle).

[bobde1234]

The behavior I see is that with a changed base idle, on ign that is replaced with 0%, and the WOT will be something like 98%. It is as if the whole scale is offset a little. And if the obstruction is removed, I would see the full 0-100% range. I’ve now taken off my tps, and they’re not a whole lot of adjustment in the position of it. My feeling is that it is not made to adjust. 

[dirtrider]

1 hour ago, bobde1234 said:

The behavior I see is that with a changed base idle, on ign that is replaced with 0%, and the WOT will be something like 98%. It is as if the whole scale is offset a little. And if the obstruction is removed, I would see the full 0-100% range. I’ve now taken off my tps, and they’re not a whole lot of adjustment in the position of it. My feeling is that it is not made to adjust. 

Afternoon  bobde1234

 

The 1200 hexhead TPS is not designed to be manually adjustable. Just electronically learnable. 

 

In any case when reassembled just verify that you have 0-100% closed throttle to fully open throttle  (verify no tight throttle cable first).

[bobde1234]

Sounds good. I got the second throttle body assembled with the new throttle shaft, and shimmed the throttle plate and it looks good. But on this side, unfortunately, my base gap has changed when it’s shimmed. In fact I have zero gap when i shim it with 0.0025 (with old throttle shaft the gap was 0.0025). I do Ingle checked my other throttle body and those measurements hold. So, I think on this throttle body, I will have to slightly change the base idle screw. 

[dirtrider]

27 minutes ago, bobde1234 said:

Sounds good. I got the second throttle body assembled with the new throttle shaft, and shimmed the throttle plate and it looks good. But on this side, unfortunately, my base gap has changed when it’s shimmed. In fact I have zero gap when i shim it with 0.0025 (with old throttle shaft the gap was 0.0025). I do Ingle checked my other throttle body and those measurements hold. So, I think on this throttle body, I will have to slightly change the base idle screw. 

Evening  bobde1234

 

Before you move that screw take a close up picture of it's present position (baseline), then pay very close attention of how far you turn it to get your needed gap. That way if it doesn't work out you can put it back to where it was.    

[bobde1234]

I’ve put a paint dot on the screw head and on the plastic base. But before I go and do that I think I’ll replace the old throttle shaft with plate and re-align it, as a sanity check. 
 

With the original shaft in place I saw the base gap I expected. Then I replaced it with the new shaft and confirmed my gap was too tight. I ended up backing out the base idle screw a little over 1/4 turn. When I reinstalled the tps I saw 1750 ohm (same as with old shaft). So I’m feeling pretty good I’ve preserved the original throttle plate opening and equal on both throttle bodies. At least close enough that I think the idle steppers can equalize it. 

[dirtrider]

12 hours ago, bobde1234 said:

I’ve put a paint dot on the screw head and on the plastic base. But before I go and do that I think I’ll replace the old throttle shaft with plate and re-align it, as a sanity check. 
 

With the original shaft in place I saw the base gap I expected. Then I replaced it with the new shaft and confirmed my gap was too tight. I ended up backing out the base idle screw a little over 1/4 turn. When I reinstalled the tps I saw 1750 ohm (same as with old shaft). So I’m feeling pretty good I’ve preserved the original throttle plate opening and equal on both throttle bodies. At least close enough that I think the idle steppers can equalize it. 

Morning  bobde1234

 

At least close enough that I think the idle steppers can equalize it. ---  Your idle steppers can equalize a lot, BUT, to do that equalization they MUST be operating independently from each other. Once you get it back together & get a GS-911 on that motorcycle you will see how little they actually run independently at times. If they are locked together at the same commanded counts then they can't equalize anything side to side, they can still control idle speed when locked together but not cross side balance.   

 

Your big test will be in how close your hot engine curb-idle cross-side balance is with the steppers working, but NOT operating independently (in sync at the same commanded counts). Do your testing/checking with the Evap system purge hose disconnected & the TB nipple plugged off. The fuel tank will still vent with the Evap purge hose disconnected, it just can't suck in & burn the stored hydrocarbons in the Evap canister. When it is purging that is basically a calibrated vacuum leak. 

[bobde1234]

Dirtrider

 

Thanks for the additional info, I’ll be looking at the stepper info for sure. Bmw  could have saved some headaches if these pulleys were steel or aluminum lol. Interesting they are still the same in the r9t. 

[dirtrider]

1 hour ago, bobde1234 said:

Dirtrider

 

Thanks for the additional info, I’ll be looking at the stepper info for sure. Bmw  could have saved some headaches if these pulleys were steel or aluminum lol. Interesting they are still the same in the r9t. 

Morning  bobde1234

 

Pressed steel is OK as long as they are plated so don't corrode, aluminum not so much as that is difficult to prevent long term wear from the cables in certain conditions like dirt roads or muddy/dirty road water riding. 

 

The plastic is OK & has been wearing great on automobiles for a long time now. It is just a poor design from BMW as there isn't enough metal extending into the plastic cam. If you break a cam off & look closely at the design it allows the cam to actually wedge itself apart in use. Then once small cracks start it keeps opening the cracks in use due to that wedging action.