Ridemalibu Motorcycle Rentals & Tours – Los Angeles CA
  1. The site owner Todd had surgery on Monday, and will be very slow to respond to all inquiries, including online Store questions.
  2. Ciao Guest - You’ve landed at the ultimate Guzzi site. In SoCal? See the SERVICE tab above for the best in service, tires, tuning and installation of our products or custom work. NEW FORUM REGISTRATIONS REQUIRE EMAIL ACTIVATION - CHECK YOUR SPAM FOLDER - Use the CONTACT above if we can be of help. ALWAYS TRY A SEARCH BEFORE STARTING A NEW TOPIC - Most questions you may have are already answered on the Forum with FACTS, NOT OPINIONS. PLEASE DON'T BE A DRIVE-BY POSTER: As a common courtesy, check back if you are posting elsewhere on the web. Note there's decades of Guzzi hands-on experienced help on this site, all whom give endless amounts of their time for free; BE COURTEOUS AND RESPECTFUL! Also be sure to click on the STORE link also above for our 600+ product inventory, including many of our 100% Made-in-house-USA GTM products and engine kits. We appreciate the consideration, understanding and your business... past and future. And if you haven't seen our MotoCycle (not) art, click on the BUILDS tab above to see our work at our sister business; GT MotoCycles® -- WE ARE ONLINE ONLY - NO PHONE CALLS MADE OR RECEIVED.
  3. There is ZERO tolerance on personal attacks and ANY HYPERLINKS to a PRODUCT or other competing website(s), this includes personal pages, social media or other Forums. We work very hard to keep info relevant here. First offense is a note, second is a warning, third time will get you banned from the site. Sorry to have to do this, but we don't have the time to chase these. This is NOT a social media platform; It's an ad-free, privately funded website, in small help with user donations. Be sure to see our online STORE link above; GTM product purchases help support the site, or you can upgrade your Forum profile or DONATE via the link above.

The Sacred Screw, the elusive 4.8, my story

Discussion in 'CARC' started by Nordicnorm, Aug 11, 2014.

  1. V700Steve

    V700Steve GT Reference GT di Razza Pura

    Joined:
    Dec 8, 2008
    Messages:
    1,063
    Likes Received:
    405
    Location:
    Atlanta area, GA
    The bikes came out acceptable but could be better with a flow bench set up. Same bikes had issues with stepper, that's how they got messed with instead of changing stepper.
    Later plastic stepper is way up in price from when they came out at least 10yrs ago.
     
  2. Steve roddy

    Steve roddy Just got it firing!

    Joined:
    Jul 5, 2020
    Messages:
    19
    Likes Received:
    0
    Location:
    Florida
    Mines running better than ever just from fixing some small vacuum leaks and valve adjustment and cat removal .I’ve had it about a year and don’t know much of its history since po was deceased when I bought it from his wife. I know from the mileage it hadn’t been ridden much and aside from a few hand written notes in service manual that’s about it. I’m going to do the sync and reset this week sometime. I wonder if some of the language about the tb being unusable is to some degree is lawyer talk to keep big brother content as far as tampering and emissions go.
     
  3. scottmastrocinque

    scottmastrocinque Scott Mastrocinque GT Famiglia

    Joined:
    Jun 26, 2011
    Messages:
    1,279
    Likes Received:
    984
    Location:
    Findlay, Ohio
    Although that method might be a crude band-aid, it is not very accurate. If it were that simple, the factory would have said so. They said the exact opposite.

    The screw is set at the factory flow bench, then fixed with solder and/or paint.

    You have to consciously screw with it to muck it up. Not recommended.

    Caveat emptor.
     
    john zibell likes this.
  4. tobinh

    tobinh Cruisin' Guzzisti GT Famiglia

    Joined:
    Oct 15, 2016
    Messages:
    164
    Likes Received:
    89
    Location:
    Burnaby, BC
    I'm not sure why you're persisting... do you have some reason to disbelieve the situation as described? what seems unlikely to you about the flow bench answer?
     
  5. Steve roddy

    Steve roddy Just got it firing!

    Joined:
    Jul 5, 2020
    Messages:
    19
    Likes Received:
    0
    Location:
    Florida
    I’m just curious and find it strange and quite frankly unbelievable that there’s no practical way way to readjust if necessary. It’s just my nature to try to understand things that seem out of the ordinary.
     
  6. scottmastrocinque

    scottmastrocinque Scott Mastrocinque GT Famiglia

    Joined:
    Jun 26, 2011
    Messages:
    1,279
    Likes Received:
    984
    Location:
    Findlay, Ohio
    Curiosity is one thing but you seem unprepared to accept the fact that some things just don’t tolerate tinkering with.

    All throttle-bodies are calibrated on flow benches and so were carburetors. That’s why the manufacturers put plugs over the idle mixture screws.

    When I was a young man, I thought the same way about VW Kombi Fuel infection air mass meters. The service manual tells you not to touch the wire but of course I did.

    It was a one-time-only very expensive mistake but I learned.
     
    Last edited: Jul 21, 2021
    john zibell likes this.
  7. Steve roddy

    Steve roddy Just got it firing!

    Joined:
    Jul 5, 2020
    Messages:
    19
    Likes Received:
    0
    Location:
    Florida
    I’m not wanting to tinker with anything I’m mostly curious as to why whatever the process is can’t be repeated. When I was young carburetors didn’t have the caps on the adjusters and fuel injection was for the most diesel only. Adjusting the idle speed and a/f mixture setting was part of regular maintenance. If it requires a flow bench that’s something not too awfully uncommon so it would make more sense to me to have a service procedure and specs rather than throwing a 1600.00 part away and buying a new one. Whether it’s been tampered with or not eventually it’s going to need some attention like all things mechanical.
     
  8. john zibell

    john zibell Moderator Staff Member GT di Razza Pura

    Joined:
    Oct 28, 2008
    Messages:
    8,307
    Likes Received:
    1,026
    Location:
    Huntsville, AL
    A quality flow bench at a dealer would be cost prohibitive considering if you don't mess with the screw it isn't needed. If you mess with it you pay the price for a new part. It is a matter of economics. It is expensive enough to be a dealer. Overhead just for the required software is very high as not only is there the initial cost, but the annual fee to use it.
     
  9. Nordicnorm

    Nordicnorm Cruisin' Guzzisti GT Famiglia

    Joined:
    May 12, 2011
    Messages:
    194
    Likes Received:
    71
    Location:
    Vancouver Island BC
    Square One: the TB valve is set on a flow bench to a specific CFM value. The air output of the stepper motor is calibrated to match that value for hot or cold starting and running. So is the fuel supplied by the ECU for hot or cold starting and running. This set-up meets Euro 3 emission standards. If you alter the throttle valve setting, the harmony in the system is gone. You will have more ore less air entering the throttle than what the design criteria specified. That is why MG says the throttle body must be replaced. To tell you anything else would leave them in a situation where they encourage tampering with emissions. Not likely.
    Your bike should start from cold or hot with no use of throttle whatsoever. A cold start should give you a 1250 rpm idle and stay there till the bike is fully warmed up. Once at operating temperature it will often idle lower than that. A hot start (gas station) should give you a short burst of 1750-1800 rpm before the stepper motor finds it's proper position for the engine temperature, and returns to the 1200 rpm area. After that half hour coffee break, it burbles contently up to 1200-1250 rpm area.
    I have "recued" 3 TB set-ups. If you are "out to lunch", you can use my early measurements to get started, but the key is in the idle speed, where the goal is to come close to the flow-bench target. Baby steps! If the idle is low, raise the TPS from 4.6 (if that is the reference on your diagnostic system), to 4.7, then re-set to 4.6. Go ride, and watch your idle. One decimal at a time with riding time in between. And I mean a full day in the saddle so you are sure you have a clear picture. Any idle above 1250rpm during the day is too high, so back it down one decimal step at a time.
    You should end up with hands-off starting and your fuel consumption computer in full agreement with what you meter into the tank.
    It can be done with patience and persistence (and access to diagnostics). When working as it is designed to do, it is a great system.
     
  10. scottmastrocinque

    scottmastrocinque Scott Mastrocinque GT Famiglia

    Joined:
    Jun 26, 2011
    Messages:
    1,279
    Likes Received:
    984
    Location:
    Findlay, Ohio
    This is tedious and I for one am completely over it.

    I don’t care what you do. Have at it. I’m tired of this.

    [Imagine the fun this will become when he discovers the stepper motor]

    It never ceases to amaze me when newbies to Moto Guzzi motorcycles want to have an impetuous fit at why things don’t bend to their will, rather than take at face value, the information that numerous people who have owned, ridden, and wrenched on Moto Guzzi, some their whole lives, generously share with them as well as what the factory even says.

    Do whatever the hell you want but please…

    Give it a damn rest. :banghead:
     
  11. arci

    arci Just got it firing!

    Joined:
    Dec 25, 2008
    Messages:
    12
    Likes Received:
    0
    Hello all.
    One question. Is it possible to use TPS sensor PF3C and set 150 mV at zero TPS position and after it set the 4.7 TPS position by corresponding voltage?
     
  12. john zibell

    john zibell Moderator Staff Member GT di Razza Pura

    Joined:
    Oct 28, 2008
    Messages:
    8,307
    Likes Received:
    1,026
    Location:
    Huntsville, AL
    No.
     
    Nordicnorm likes this.
  13. arci

    arci Just got it firing!

    Joined:
    Dec 25, 2008
    Messages:
    12
    Likes Received:
    0
    There is non touched scared screw TB measure from Moto Guzzi Norge 1200

    measure throtle Norge1200 (Sacred Screw).png
     
  14. john zibell

    john zibell Moderator Staff Member GT di Razza Pura

    Joined:
    Oct 28, 2008
    Messages:
    8,307
    Likes Received:
    1,026
    Location:
    Huntsville, AL

    All well and good for your bike, but due to manufacturing tolerances it will not be the same for all bikes. To accurately set a flow bench is needed.
     

Share This Page