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Syncing Throttle Bodies- Stelvio 8V

Discussion in 'Stelvio Reference Topics/Recalls' started by canuck1969, Jul 17, 2012.

  1. Ed Baker

    Ed Baker Just got it firing!

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    thanks John. Maybe I can find someone with the equipment willing to help me do it here in Austin TX area. Ultimately I'll end up buying the gear. My bike has only 2800 miles so it go awhile just fine. Seems to vibrate like a Harley at idle, and remain a little rough until really smoothing out at 4000rpm onwards. I think it's just the bikes character...
     
  2. john zibell

    john zibell Moderator Staff Member GT di Razza Pura

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    Those are indications it should be looked at. You might want to check in the South Central section to see if there is someone near you that can assist. MPH in Houston is probably the closest dealer.
     
  3. Ed Baker

    Ed Baker Just got it firing!

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    It just came back from the dealer (AF1 in Austin) , for a few infant mortality issues. BTW, they rock. Dealer says it is running as it is supposed to be. I bought the bike with 1800 miles on the clock and it apparently had a bad relay that took out the alternator, and you can guess the rest of the story. But now I've put on 1000 miles in the last week and its running very well. I guess I'm just used to BMW boxers which now seem overly refined in comparison. :) I will poke around and see if I can't check it though. Thanks for the advice.
     
  4. toma nova

    toma nova Cruisin' Guzzisti GT Contributor

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    Ed,

    I'm north of Houston, easy back roads from Hutto (79, 36, 6, 105, etc to The Woodlands). I've got an old school tube-on-board manometer and a digital CarbMate so take your pick. GuzziDiag to reset the TPS also. Easy to open up and have a look anytime. I'm also at ~4000 miles and will do a full service at 5k, hopefully before the GRIT rally. Put that on your calendar, great camp out in East TX the first weekend in October.

    Tom
     
  5. Ed Baker

    Ed Baker Just got it firing!

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    thanks Tom! I will definitely take you up on that. I'm used to servicing BMWs but this is my first Guzzi. So far I've done the basic oils (engine, tranny,shaft) is all as the bike was serviced at 1200 and I always like to start with fresh fluids as a baseline. It has about 3K on it and really runs good. Maybe I can come down and watch as you service yours and take a peak at my sync then. I will check out the GRIT rally you mentioned. thanks!
     
  6. QueenslandKen

    QueenslandKen Just got it firing!

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    Thanks very much for all the info, my first sync went well !
     
  7. Resom

    Resom Just got it firing!

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    The one thing I don't like about the Guzzi procedure is, if you have to open the RH butterfly to sync the TB's, it will actually unseat the RH throttle stop from its stop screw. This means that the RH butterfly is basically floating on the linkage rod at idle. I noticed the TPS position at idle (4.8) would bounce around between 4.6 and 4.8 while monitoring it at idle after sync because of this.

    Note: I had to turn the sync adjust screw 1/4 turn clockwise to get the TB's in sync, which is not much, but still unseated the RH butterfly stop from its stop screw.

    I know Guzzi states not to touch the stop screws, which I agree with on the LH throttle body, but I think it may be a good idea to move the RH stop screw so that after sync the butterfly is resting on it, as it was from the factory.

    Thoughts?
     
  8. john zibell

    john zibell Moderator Staff Member GT di Razza Pura

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    You don't ride the bike at idle. The movement of 4.6 to 4.8 still has the TPS in range (4.8 +/- 0.2) so don't worry about it. My recommendation is don't touch the throttle stop screw on either side. BTW, you may be opening or closing the RH butterfly, it depends on the bike.
     
  9. Resom

    Resom Just got it firing!

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    Another interesting point..! If the RH butterfly is resting on the RH stopper screw, how would it be possible to close the RH butterfly anymore?

    I'm a little confused why the RH stopper screw is there even there..?
     
  10. kiwi dave

    kiwi dave GT Reference

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    I agree, there's no requirement for a RH stopper screw since the butterfly is being controlled by the sync arm. I've set up my V11 LeMans in this fashion by removing the RH screw. There is no sacred screw on the V11 throttle bodies.

    However, that is a perfect world. You may find that slop in the sync arm means that the RH throttle body's butterfly may not rest in the same position each time. Winding the RH screw in so it just touches (i.e. no increase in engine revs) will provide a "safety net" should the slop not maintain the sweet idle you've been trying to achieve.

    Also, I've always wondered why the TPS is on the RH throttle body, any adjustment in the sync arm means the TPS has to be reset. I think it should be moved to the LH throttle body, or make the RH throttle stopper screw "sacred". I'm not even convinced how sacred the "sacred scew" is.

    Others may be able to supply better reasoning, but this is how I see it.
     
  11. Stevie

    Stevie Cruisin' Guzzisti

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    Dude, don't screw with the screw.
     
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  12. kiwi dave

    kiwi dave GT Reference

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    If the screw wasn't there for adjustment, it wouldn't be there i.e. it would be blanked off.

    How many Moto Guzzis have you purchased that were just perfect and didn't need setting up properly?
     
  13. Stevie

    Stevie Cruisin' Guzzisti

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    Go ahead and adjust the sacred screw to your hearts content. A BMW mechanic did that to an 08 GSA I owned, it took forever to get the bike to run correctly after we figured out what the idiot had done.
     
  14. kiwi dave

    kiwi dave GT Reference

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    So because a BMW mechanic stuffed you around, you think all mechanics are idiots? Get a life!
     
  15. Brian UK

    Brian UK GT Reference

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    So why does it come sealed with paint? The balance screw isn't sealed because it is meant to be adjusted.
    The screw is there because it has to be set up on a jig at assembly fairly accurately, this could not be done with just a bent bit of metal.
     
  16. canuck1969

    canuck1969 GT Reference GT Contributor

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    Not just paint, but if look closely it should also be soldered so it does not move. The tb manufacurer uses it to set the min throttle opening since it is the reference tb setting on the bike. It is set up for a specific air flow. If you move it you will loose the reference opening and will never get the right tb balance correct again without a lot of luck.

    This is not something new. Many have turned the adjuster and had a world of hurt trying to get it back. Most reported that the bike never really ran right again. Guzzi, BMW, Aprillia and just about any other twin manufacturer that uses the same tb setup. There is no benefit at all to turning the screw for adjustment so why would you do it. It is factory calibrated for a reason.

    If u want to play with it knock yourself out, but you have years of data telling u not too. Let us know how it turns out. Maybe everyone else and the factory were wrong.

    By the way, not all bike technicians are idiots........ Just the ones that do the things that they are not supposed to and believe they are better than all the other techs out there. Know a few of those and those are the dangerous ones....to themselves and the industry.
     
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  17. Bonaventure

    Bonaventure Cruisin' Guzzisti

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    Somewhat of a thread resurrect here, but from reading this excellent guide I thought there was only the one sacred screw-- on the left hand throttle body. So in fact there are two, one for each tb and then the right hand tb's throttle-stop screw is just as sacred as the left one?

     
  18. Nicolai

    Nicolai Just got it firing!

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    trying to post GRAZIE MILE to Scott Mastrocinque (i think - new to forums) !!!
    Want to try this on my 2013 Stelvio BUT
    1) I first need a Centurion S tool (or is it a cable to my laptop?), yes?
    2)the link above leads to an error page... suggestions anyone?

    Many thanks and safe holiday rides to all!
     
  19. scottmastrocinque

    scottmastrocinque Scott Mastrocinque GT Famiglia

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    Prego Nicolai. Ti ringrazio!

    The Centurion-S has been superseded by the Alaris tool.

    Todd sells it too. I have both.

    https://www.guzzitech.com/store/product/tr-alaris/
     
    Last edited: Dec 2, 2017
  20. scottmastrocinque

    scottmastrocinque Scott Mastrocinque GT Famiglia

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    REPOSTED 4/4/19 WITH LOCAL FILE POSTING: PHOTOBUCKET NO LONGER WORKS!

    No Problem. I think it becomes clear when one fully understands what is happening here, so to this end, let me offer this.

    This is my lousy drawing of the throttle-bodies arrangement on the Stelvio.


    Throttlebodies.jpg


    As you can see, there are butterfly valves inside of the throttle-bodies. As they open, more air is drawn in from the airbox to mix with the injected fuel. The blue line connecting them together, is the linkage rod so that when one turns, the other turns the same amount. The yellow arrow is the location of the fast speed throttle-body balance adjustment screw. The red arrow is the stop plate screw which is factory set and you should NEVER touch otherwise the whole thing is ruined and must be replaced! The green diamond is the TPS sensor which resides on top of the right hand side throttle body. Now let's look at real pics.

    Here is a side view , pointing towards the rear of the left hand (sitting on the bike) throttle-body. The colored arrows match the previous diagram. Yellow is the adjustment screw, red is the stop plate screw you never touch.

    GuzziThrottlebodies002_640x480.jpg

    Here is the same side taken from a more straight on angle. Again, yellow arrow is adjustment screw, red arrow is factory set stop plate screw you do not touch, and now the white arrow shows the connecting rod which goes over to the right hand side throttle-body (in my lousy graphic, this was the blue line connecting the two throttle-bodies together).

    GuzziThrottlebodies003_640x480.jpg

    Here is the best view. Notice the white circle which shows the connecting rod going all the way over to the right hand throttle body, and the red circle which shows the factory set stop plate screw resting against the stop post from the throttle-body. This is why you never adjust the stop plate screw (red arrow) because this distance is a factory calibration which is linked to the fuel injection software as to it's position, approximately 4.9 degrees. Basically this distance is a constant so that the fuel injection map, which depends upon throttle POSITION (i.e. open or closed within it's range of motion) is calibrated at a ZERO point. It will make more sense in a moment.

    GuzziThrottlebodies004_640x480.jpg

    This is the throttle-body on the right-hand side. The green diamond is the TPS sensor. The white circle shows the connecting rod coming from the left-hand side which connects to the right-hand side. The throttle cable only attaches to the left-hand side throttle-body. All movement on the right-hand side is controlled by this linkage rod. You never adjust or change this rod. It too, is factory set.

    GuzziThrottlebodies005_640x480.jpg

    GuzziThrottlebodies006_640x480.jpg

    Now, let's look at the bleed screws. Left-hand side first. It is the blue arrow and you can make out the hex head on the inside of the screw. You can also see an excellent view of the factory set stop plate screw in the red circle.

    Also look carefully at the yellow arrow (the fast speed throttle body balancing screw). See the mechanism with the spring? When you turn this screw, it allows the secondary plate (on the right side of the spring)to move INDEPENDENT from the left side of the spring. So, the plate on the left side of the spring is the left-hand throttle-body. It NEVER moves from the factory set position. The plate on the right side of the spring, is connected to the control rod which goes over to the right-hand side throttle body. Thus, when you adjust this screw, you are physically moving the butterfly valve in the right hand throttle-body! Get it? )You can see the two independent plates in the second photo) The left side never moves adjustment wise, but the right side can be adjusted in or out as needed to balance the high speed balance. Remember, the TPS sensor sits on top of the right-hand throttle-body - i.e. the one that can be MOVED. The fuel injection computer orders the injectors to do their thing based upon certain conditions which it always is evaluating, one being throttle position, and if we moved the butterfly valve on the right-hand throttle-body, the TPS will read an incorrect position (voltage) from the TPS sensor from the get go and our fuel injection map will be out of alignment with actual operating conditions.

    Now this is WHY you need to be able to reset the TPS. Remember that the TPS position is linked to the fuel injection map in the ECU. In order for the throttle position and the fuel injection map to be in alignment there has to be a synchronized ZERO point. That point is the value set by the factory on the left-hand set plate screw of usually 4.9 degrees and this is why you NEVER adjust this screw. But we do reset the TPS so that the altered-position of the right-hand throttle-body, is set to match the factory baseline setting of 4.9, (this is what the left-hand side will ALWAYS BE - IT CANNOT EVER MOVE SO LONG AS YOU DON'T TOUCH THE STOP PLATE SCREW) regardless of where it actually is, so that everything is in alignment. Left-hand side physically and permanently always at 4.9 and right-hand side electronically reset to 4.9, irregardless of where it actually might be in order to properly balance the throttle-bodies. Does it now make perfect sense? Now you understand precisely WHAT is happening and when.

    So, when we adjust the fast speed adjustment screw, we are moving the right-hand throttle body out of alignment from the permanent factory setting on the left-hand side, in essence, because the TPS sits on top of the right-hand side, we have moved the alignment of the throttle position with the fuel injection map. Bad thing - crappy running motorcycle.

    So, when we RESET the TPS, we are telling the ECU that the value it is reading from the TPS sensor on the right-hand throttle body, should be the ZERO point (in actuality, the 4.9 factory setting which is what the left-hand side is), REGARDLESS of where the right-hand side has been moved to, thus aligning the throttle position and fuel injection map, while maintaining the actual true zero point which is physically set by the stop plate screw on the left-hand throttle-body at the factory.

    We are commanding the ECU to recognize and program that at whatever position the right-hand throttle-body is at right at that moment (remember, we may have moved it left or right by adjusting the fast speed throttle-body balance screw), should be reset to the baseline 4.9 (in this particular model, others are different). We are setting that ZERO point to align the TPS sensor and the FI map to the actual operating conditions (the real position of the right-hand throttle-body).

    Had the factory put the TPS sensor on the left-hand throttle body, we would never need to reset the TPS and could move the fast speed adjustment screw anytime we needed to without worrying about a TPS reset. However, because they put the sensor on the RIGHT-HAND throttle-body, and because this position can be changed via the fast speed adjustment screw, we must be able to tell the computer to reset the zero position (which it reads on the right-hand throttle body via the TPS sensor) after we've made changes to the fast speed balance adjustment screw. I hope this makes complete sense now. :geek:

    AirBleedScrews002_640x480.jpg

    GuzziThrottlebodies004_640x480.jpg

    Let's look at the right-hand side air bleed screw. Again, you can see the hex head inside of the bleed screw. These screws are a BEAR to get to, especially the left-hand side.


    GuzziThrottlebodies006_640x480.jpg

    AirBleedScrews004_640x480.jpg

    AirBleedScrews003_640x480.jpg


    So, the general idea is this.

    1. Connect your Centurion to the bike and turn the ignition switch on. Reset the TPS with the Centurion. (We are establishing a ZERO point based upon the position of the right-hand butterfly valve position).

    2. Close BOTH air bleed screws. More than likely, only 1 will be open. Remember, closed, but not crushed! A light touch works really well here.

    3. Place a large high-velocity fan right in front of the motorcycle, blowing towards the motorcycle to keep air flowing over it during this procedure. This is a MUST DO to avoid overheating! Bring engine to operating temperature > 60 degree Celsius (The Centurion you can buy from Todd here on the forum, will display the engine temperature from the engine temp sensor, very handy).

    4. Turn off engine, attach your CarbMate, mercury stick, or whatever tool you are using to balance the throttle-bodies, to your vacuum ports on the bottom of the throttle-bodies, one on each side.

    5. Turn engine on, and have an assistant raise speed to approximately 3800-4000 rpm and hold it there steady. Look at your balancer, and adjust the fast speed throttle-body balancing screw to bring the throttle-bodies into alignment. Turning the screw one way will raise the right-hand vacuum and turning it the other way will lower the right-hand vacuum. You will understand when you do it. CAUTION! It is easy to push on the screw while you are turning it, and this will raise the rpm erratically (you are pressing in the linkage and moving the connecting rod). The trick here is to ROTATE the adjustment screw WITHOUT pushing against it. It takes some getting used to. When you are doing it, you will instantly notice if you are pushing against the screw because your engine speed will change. Personally, I use a socket attached to a screwdriver-type handle to rotate the screw but you will have to scrape away some of the yellow marking paint for your socket to slide on easily. The socket allows for better rotation without pushing into the screw. When the fast speed adjustment is balanced, release the throttle back to idle. Turn off the engine and reset the TPS again. (We are resetting the zero point now that we have changed the position of the right-hand throttle-body via the fast speed balancing screw). When done. Disconnect your Centurion from the motorcycle.

    6. Start engine again and blip the throttle and then release it and allow it to click back against the stop screw. Now at idle, what does your balancing tool say? More than likely it will read different values. The side that is HIGHER, is the side you want to open the air bleed screw on, thus allowing more air to enter and thereby reduce it's vacuum. (Don't touch the other side air bleed screw. It's not necessary.) Only one side is the higher side and if we open that side's air bleed screw, it's vacuum will become less, and as you adjust (open) the screw, the balancer tool you are using will show the throttle-bodies come into idling alignment. Once the alignment is the same for both throttle-bodies, by having adjusted ONLY the higher side, you are done!

    7. Turn off engine, disconnect balancer tool, cap off your vacuum ports, and smile. You did it.

    I sincerely hope that this explanation helps you. Good Luck! :D
     
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