TPS adjustment/throttle body sync - 99 R1100

[rlusher]

Hello. I followed Stephen Karlan's 12-step method for adjusting the TPS and syncing the throttle bodies:

 

1. Loosen throttle cable (left side)

2. Loosen throttle body crossover synch cable (right side)

3. Back out the left throttle plate stop screw (underneath left side)

4. Attach DVM to red-white TPS wire #1 (rear) - ignition on

5. Move TPS to obtain zero reading (.006 volts) and lock TPS

6. Move left throttle plate stop screw to obtain .370 volts and lock screw

7. Large brass bypass screws in, bike on, warm engine, rough idle expected

8. Turn the large brass bypass screws out in 1/4 increments if bike will not idle; attach carb stix

9. Set right throttle plate stop screw using carb stix

10 Reduce TPS in increments of 0.020 if idle exceeds 1100-1200 rpm

11. Reset throttle cable (left side) to .5 mm free play

12. Perform the "Throttle Body Synch for Dummies"

 

All went like clockwork until step 7. I cannot get the bike to remain running so I can balance the throttle bodies (step 9). I adjusted the brass screws to try to increase idle, but it does not make any difference. It just runs very rough and quits.

 

One part of this method I am not 100% about is the free play in the throttle cables. Does this involve simply loosening the knurled adjuster until there is ~.5mm slack when I tug on the cable?

This could be where things are going wrong.

 

Anyone tried this method and had issues?

 

My bike surges quite a bit, and that is why I was doing this.

 

Thanks for any input!! This forum is a tremendous help.

[Twinsig]

http://advwisdom.hogranch.com/Wisdom/

 

This may be what you need, worked for me, one day you too will have that moment when it "clicks".

[rlusher]

Hi Twinsig. Thanks for the reply. Which document do you recommend? I have read the TBSD document, which seems to be most closely related. There is lot of good information there. I will bookmark the page for sure. Thanks again.

[Edgar]

You are correct on your assumption on the free play on the throttle cable. Is the throttle cable seated correctly in the adjuster? Not idling well or running on 1 cylinder is an indication of this, especially with no prior history of this behavior.

[Twinsig]

TBSD

OVAD is another

 

[rlusher]

Hi Edgar. Thanks for the clarification. Yes, I double-checked the cables and they are seated properly. To adjust them to 0.5mm play was a pretty significant adjustment away from where they already were. I wonder if this has any bearing...?

 

Another thing. I had cleaned the brass screws with carb cleaner (cat safe), and reinstalled them (per advice from another post). I restarted, then checked the screws again (don't know why, was just curious), and the left side one was all gunked up again, even after I had just cleaned it. Could this indicate something awry on the left side (same side as the TPS)?

 

Thanks again!

 

Beginning to think I should have left it alone. It really was running OK, but I want it perfect! The good thing is I learn something new every time I go on one these adventures, LOL.

[Jim Moore]

One part of this method I am not 100% about is the free play in the throttle cables. Does this involve simply loosening the knurled adjuster until there is ~.5mm slack when I tug on the cable?

This could be where things are going wrong.

 

You need to turn the adjusters on the lower throttle cables. Basically you want to make sure the stop screws are touching the plates, plus a small amount of slack.

[Boffin]

One part of this method I am not 100% about is the free play in the throttle cables. Does this involve simply loosening the knurled adjuster until there is ~.5mm slack when I tug on the cable?

This could be where things are going wrong.

 

You need to turn the adjusters on the lower throttle cables. Basically you want to make sure the stop screws are touching the plates, plus a small amount of slack.

The 0.5mm (about 0.02 inch) is not critical - just a very small amount of clearance that is the same all-round.

 

Andy

[Peter Parts]

I wonder how many 1999 bikes have not had the setting on their idle stop screws screwed up?

 

Ben

[rlusher]

Thanks guys! Let me make sure I understand. I need to adjust the throttle cables using the knurled adjuster until they are just touching the stop screws?

 

Peter Parts, can I find some comfort in knowing that I am not the only one that has done this kind of thing?.....LOL

[Jake]

Let's go back to some base information for a moment. The stop screws at one point in their life were paint sealed. Did you or a previous owner adjust those screws - is the paint seal broken?

 

In answer to your question, the throttle cables should be adjusted (by the knurled adjuster) so that the tension is not holding the throttle plate off the stop screws. So, that means they should be adjusted so that the throttle plate is just touching the stop screws, plus 1/8th of a turn of slack - so they are definitely touching. This will give you a small amount of play at the throttle before revving. It all starts with the stop screws, however. If those babys are slightly off, they at least need to be off the same amount on both sides! Otherwise your throttle plates will open at different times/rates, and the airflow is exponentially different at various low RPM throttle positions. This would give you fits when trying to balance/synch the TBs.

 

Where in FL are you?

[rlusher]

Hi Jake.

 

I am not sure if anyone before me turned the screws, but they did not appear to be sealed (although there is blue paint visible). Does not matter now, LOL. This is great info. Thanks. I took a few steps back from this to try to understand the process better conceptually. So far, I have just been blindly following the steps. From the posts here, and the "Throttle Body Syncing for Dummies" article, I now understand it better (at least better than before, anyway). I am going to give it another try starting from the beginning, and will pray for better success. I believe a lot of my problem was that right side was grossly out of whack before I ever cranked it.

 

I'll re-post with results.

 

To answer your question, I am in Ocala.

 

Thanks again.

[OoPEZoO]

I don't know if this will help at all, but here is a link to the thread I started when I rebuilt my throttle bodies on my RT LINK

 

I had to start with both throttle bodies and stop screws from scratch and got them dialed in damn near perfect. The bike ran great until I retired it a few months later due to a transmission failure. The throttle bodies were sold to another board member and are (as far as I know) still going strong on his bike. Give a yell if you have any questions.

[Jake]

Keep at it and keep asking questions. There are, however, a number of items that can conspire against you having immediate success, particularly on an older bike. I'd really suggest removing the big black plastic intake tubes on both sides (slide toward Airbox- they should be tight) and clean them out. While those are off, remove the larger brass screws and hit the throttle bodies with a little compressed air and some carb cleaner. A flashlight is your best friend - poke your head in there and see if there is any wayward gunk. Manually open the throttle bodies and look in there to ensure the butterfly valves can open and snap closed without impediment. Check the air filter while you are at it.

 

The intake tubes have an o-ring which will need to be carefully reseated when replacing the tubes. They have a nasty habit of binding on the opposite side of your view, and this alone can create an airleak inbalance.

 

Ensure your throttle cables are free flowing and not hanging up. Visually check the throttle cable seats and channels/guides on the throttle bodies to ensure they are free from debris. A little pebble can be a culprit.

 

Once clean and clear, then start with your procedure one step at a time. Conceptualize what you are doing, which is setting the left side throttle body perfectly, then balancing the right side to match that. Both throttle cables should begin their pull at the same time. The brass screws should be roughly the same, which is 1 1/2 turns out from fully seated (but lightly - Brass is soft) as your starting point, then adjust from there to fine tune the idle, getting the left side done first, then fine tune the right. The brass screws are only for idle matching, you will later use the knurled adjuster on the right throttle body for your higher rpm balance adjustments, using whatever meter (Carbtune, Twinmax) you have. Keep your fans blowing and don't let your bike cook.

 

If it's still a mess, let me know. I'm not too far away and can give it a look. If it ends up with both of us scratching our heads then at least we will have eliminated some variables.

 

Good luck!

[rlusher]

Thanks Keith. Great info.! Maybe there is hope for me, LOL.

[rlusher]

Thanks Jake! I printed this out to add to my growing library of TB info.

 

Let me ask a question. Once I get the left side squared away (using the voltmeter/stop screw to set the TPS), what should be my starting point with the right side stop screw (now that I have already messed with it) and throttle cable relative to the plate? Again, I think the right side is where I am going wrong. Thanks so much for the offer to put eyes on it!

[roger 04 rt]

The paint on my throttle stops and TPS are original so my TB balances are BBSs with the throttles on the stops and a right-side adjustment at 3000 RPM.

 

Reading through the thread it seems like there are several moving parts.

 

For the 3000 RPM & Right Side adjustment don't I want two things: throttles coming off the stops at precisely the same moment and equal intake manifold vacuum?

 

Then with the throttles on the stops, the BBS take up any difference even if that means the BBSs are somewhat unequal?

 

I noticed that when I pull the fast idle lever up, even though idle and 3000 RPM are good, that there is a vacuum imbalance--modest, a few bars on the Harmonizer.

 

Does anyone know at idle, what percentage of the air flows through the BBS?

 

RB

[OoPEZoO]

Once I get the left side squared away (using the voltmeter/stop screw to set the TPS), what should be my starting point with the right side stop screw (now that I have already messed with it) and throttle cable relative to the plate? Again, I think the right side is where I am going wrong. Thanks so much for the offer to put eyes on it!

 

If your throttle plates are properly centered in the bore of the throttle body, then you should be able to just eyeball the right side throttle stop screw to match the left side. As long as it is close, you should be able to fine tune the balance using the brass screws. Thats how I did mine at least and they were almost identical when I finished up. With the ignition on, but not running I set the left side throttle stop screw to get .385V at the TPS. Once its set, open the throttle plate and let it snap shut a few times to make sure the .385V is repeatable. Then I eyeballed the right side throttle stop screw to match the left. I set both brass screws to 1.5 turns out from seated. Then I reinstalled the throttle bodies back onto the bike. I adjusted the throttle cable on the left side for the appropriate slack called out in the manual and then adjusted the right side throttle cable to get it as close as I could to match the left. I did this by opening and closing the throttle slowly, and listening to the throttle pully bottom out on the throttle stops. If you hear two *click* *click*, then they are not closing at the same time. You want to adjust the right to hit the stop at the exact same time as the left. I fired up the bike and let it sit until warmed up (W/ a box fan blowing on the heads/exhaust). Once warmed up I adjusted the brass screws to dial in 1100 RPM and even vacuum from both throtte bodies. In my case, that required about a 1/4 turn on each brass screw (I can't remember if it was in or out). once you have the idle set and even. Turn the throttle to get the RPMs up and adjust the right side throttle cable to make sure the vacuum stays even between the throttle bodies. I usually picked 4000-5000 RPMs as the point where I balanced it as that is where I spent most of my time riding. If all goes well, then you should be all set at this point.

 

If you run into a snag, following the above procedure should help you narrow down the problem. For instance.....before I rebuilt my throttle bodies, there was no way in hell I could ever get that .385V to be repeatable because the throttle plate shaft in the left side throttle body had a notch worn in it. This made the shaft have slop in it, which in turn caused the TPS to get improper throttle position and put out an inconsistant voltage. I could grab the pully, rock it around, and see the TPS voltage go all over the place. Everytime I would snap it shut, it would rest at a different voltage ranging from .346V to .418V. After the rebuild it was rock solid and dead nuts repeatable. It dropped right to .385 and stayed there after each throttle closing. The right side throttle plate shaft was no better. There was lots of slop between the shaft and bushings that it rode in. Afterwards, it was nice and tight with smooth operation. Once I got it all figured out, it makes perfect sense why my bike was running like crap. The computer had no idea what position the throttle plates were actually in. The TPS was feeding it bad voltages and the computer was trying to compensate for that. Hope that gets you going in the right direction

[OoPEZoO]

The paint on my throttle stops and TPS are original so my TB balances are BBSs with the throttles on the stops and a right-side adjustment at 3000 RPM.

 

Reading through the thread it seems like there are several moving parts.

 

For the 3000 RPM & Right Side adjustment don't I want two things: throttles coming off the stops at precisely the same moment and equal intake manifold vacuum?

 

Then with the throttles on the stops, the BBS take up any difference even if that means the BBSs are somewhat unequal?

 

I noticed that when I pull the fast idle lever up, even though idle and 3000 RPM are good, that there is a vacuum imbalance--modest, a few bars on the Harmonizer.

 

Does anyone know at idle, what percentage of the air flows through the BBS?

 

RB

 

If I remember correctly, the fast idle cable only opens the left side throttle body......hense the imbalance

 

You are correct on all other points

[rlusher]

Printing this, too, Keith. This seems to put the icing on the cake for me. Thanks!

[dirtrider]

Afternoon Rick

 

The fast idle cable/lever opens BOTH side TB's same as twisting the twist grip. (it won't run worth a hoot if only one TB is opened)

 

On the very early 1100's a long single throttle cable ran to the L/H throttle body cam, then around the cam & on to the R/H TB. The fast idle cable acted on the L/H TB but that crossover cable assured both side TB's opened pretty well together with the fast idle cable.

 

The later 1100's (like your 99) has a Bowden box & on that the BOTH the twist grip & fast idle cable/lever move the cam/pulley in the Bowden box. From there very short cables run from the Bowden box to both side TB'S & operate them equally (if cable adjusters are set correctly).

 

If you are getting a different cross side vacuum between the twist grip & fast idle lever then look for an issue inside the Bowden box like a worn pulley bore or cable entry issue.

 

I wouldn't let a small vacuum difference on fast idle worry me though. The one you want correct is when the twist grip is used.

 

[roger 04 rt]

My fast idle, as I mentioned, is a bit unequal. Not enough difference to run it down. Next time I have the plastic off I may use a feeler gauge to see how many degrees it's different by lifting the lever, blocking the right side with a feeler gauge and and twisting the left side and watching the TPS. More curiosity than anything.

 

I've noticed that a tiny turn on the RH adjuster at 3000 RPM moves the Harmonizer from one side to the other. Small enough that tightening the lock nut throws it off.

[Twinsig]

Rlusher is working his way to the moment when it just clicks, that AH-HA moment where so many others have been before!

 

Keep it up bro, your getting close, when you grasp this TB balance concept you'll be able to adjust the right side cable with enough offset to tighten the nut and achieve balance.

Now, if someone could show me how to tighten this loose nut in my head!

[AnotherLee]

Hi, Roger -

 

I've noticed that a tiny turn on the RH adjuster at 3000 RPM moves the Harmonizer from one side to the other. Small enough that tightening the lock nut throws it off.

 

You've probably already figured this out but I use a pair of long nose pliers to hold the adjuster while I tighten the lock nut. Works well for me.

[philbytx]

Marc Parnes made a great knurled adjuster for oilheads but they are now out of production. Fortunately I bought one for the RT a few years back....

[OoPEZoO]

Marc Parnes made a great knurled adjuster for oilheads but they are now out of production. Fortunately I bought one for the RT a few years back....

 

+1......One of the few parts that I could actually move from my old RT to my GS. I was very pleased to find out that it fit. It makes adjusting that throttle cable a lot easier

[rlusher]

Thanks to all for all the great info.! I will not be able to work on this for another week or so, but will post results when I do. This forum is amazing in that a week ago I thought I had messed this thing beyond my ability, but after these replies, I believe there is hope. Thanks again.

 

-Rick

[philbytx]

Hey!

perhaps we could email Marc and ask if he would produce a batch for BMWST.COM?

 

How many takers on here???

 

 

[AndyS]

Ah, would he ship to the UK?

[philbytx]

I'd ship them to you mate as they are very light !

Just need to find out if he WOULD make a batch but then we need to know how many folks are interested in buying a pair.

 

 

[waynerd]

Every 6K miles I start obsessing about a differential screw adjuster idea. Then I muddle through the balancing, button everything back up cause I'm anxious to ride and promptly forget about it 'til the next service interval.

 

I learned about the adjuster knob from this prior thread . Much simpler than my idea and it would provide a definite improvement. Taylor1 (Dave) sent me a drawing of the knob that he got from Marc Parnes. He was going to make one for himself. He made it sound like Parnes is no longer willing, or able, to make them. I lost my access to a decent lathe & mill, so I never did make one.

 

I'd be interested in one (and I think I only need one, not a pair, right?). Or if we got permission, could maybe find an enterprising shop to crank some out.