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Thread: Throttle Body Sync?

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  1. #1

    Question Throttle Body Sync?

    FWIW -

    Have nearly 16,000 miles on my R-12s since buying it in May, of last year. My question involves throttle body sync adjustments and out of adjustments.

    Specifically, done all the Dealer Mx/Svc. Here's my feedback on sync/valve adjustments:

    o Out of the box, in Denver, the bike was "buzzy."

    o Next day, changed oil at 200 mile, sync adjusted and most of the "buzz" went away.

    o The 600 mile service sync/valve adjustment, in SLC, brought back a mild buzz.

    o The 6,000 mile sync/valve adjustment, in CLE, made the bike ride "baby butt" smooth. Stayed that way until the 12K service.

    o The 12,000 mile sync/valve, in Den, brought back a mild buzz that continued to get worse.

    o Got my second set of M-3s (have gone through three sets total, original set was M-1s) at 16,000 miles. Mentioned buzz. They re-synced throttles and now it's gone back to being baby smooth.


    In summary, from 6K to 12K the bike ran like glass and the sync never varied. However, from 12K to 16K it seemed out of sync and distinctly got worse.

    In conclusion, what causes the throttle sync to remain stable? And what causes it to wander.

    Any insight from our resident motor-heads???

    With interest and appreciation....

    J.K.

  2. #2
    gulfcoastbeemer
    Guest
    After letting my BMW dealer perform all valve and throttle-body adjustments with mixed results, I performed my own valve adjustment and throttle-body sync at 21,000 miles on my '07 R1200RT. The results were a dramatically smoother engine. I could immediately feel the difference as well as see it in the mirrors

    Before I performed the throttle-body sync, I adjusted the valves with the engine stone cold. I used a Twinmax throttle-body balancing device.

    And, for what its worth, I didn't disconnect the "stepper motors" during the TB sync, and I optimized the sync at about 3,750 RPM, where the engine spends a lot of time.

    I'm pretty methodical and slow as molasses in January when I work on my bike. I'm not sure all professional mechanics or shops have this luxury. That could be the reason some tune-ups are better than others.

  3. #3
    A bozo on the bus deilenberger's Avatar
    Join Date
    Mar 2003
    Location
    Spring Lake NJ, USA
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    8,485
    WAG:

    I suspect the most critical adjustment on the hexhead engine is valve adjustment, and it's possible the valves drifted a bit and finally settled in between the 12k-16k interval where things were buzzy.

    It would seem that once the throttle cables stretch-in, they should stay pretty stable until they start to fail. When I've adjusted my valves and then checked sync with a Twin-Max, the sync has been dead-nutz on. The steppers are primarily for idle balance and idle speed, and are probably a very insignificant factor above idle (small-hole vs large hole when the throttle plate starts opening..)
    Don Eilenberger http://www.eilenberger.net
    Spring Lk Heights NJ NJ Shore BMW Riders
    '12 R1200R - I love this bike!

  4. #4

    Cool

    Quote Originally Posted by gulfcoastbeemer View Post
    After letting my BMW dealer perform all valve and throttle-body adjustments with mixed results, I performed my own valve adjustment and throttle-body sync at 21,000 miles on my '07 R1200RT. The results were a dramatically smoother engine. I could immediately feel the difference as well as see it in the mirrors

    Before I performed the throttle-body sync, I adjusted the valves with the engine stone cold. I used a Twinmax throttle-body balancing device.

    And, for what its worth, I didn't disconnect the "stepper motors" during the TB sync, and I optimized the sync at about 3,750 RPM, where the engine spends a lot of time.

    I'm pretty methodical and slow as molasses in January when I work on my bike. I'm not sure all professional mechanics or shops have this luxury. That could be the reason some tune-ups are better than others.
    Thanks guys -

    Stone cold engine may be the secret. Woody, at BMW of Cleveland, spent a full 30minutes dickering with the valves, then sync, to dial her in. Know when I do my other R90S and /6, a few judicious hits with the mallet on the cam bolt removes any double images of the timing marks, and really smoothes out engine vibrations. So much for the virtue of points and plugs.

    Also, since I tend to keep the RPMs between 4,000 - 4,500, some tune-ups may keep my humping hamsters happier than others.

    Anyway, the new ride keeps me "slow" happy. The only thing that gets tired is changing the tires.

    Thanks, again.

    J.K.

  5. #5
    bob1100rtc
    Guest
    My 07 RT was pretty smooth on delivery. The only thing I noticed was an occcasional stall on a hot restart. After the 600 mile service (done at 850) there is definately more vibration,an occasional pop when I blip the throttle to down shift , and it stalls more frequently on a hot or cold start. I'm at 2,750 miles now. Before I bring the bike out of hibernation, I intend on rechecking the valves and tb's. I'm also going to change the oil in the engine,trans and fd. That way I know whats in there. I had the dealer do the 600 mile only for warranty purposes. It was torture to let someone else work on a vehicle of mine.

  6. #6

    Cool

    Quote Originally Posted by Bob1100RTC View Post
    My 07 RT was pretty smooth on delivery. The only thing I noticed was an occcasional stall on a hot restart. After the 600 mile service (done at 850) there is definately more vibration,an occasional pop when I blip the throttle to down shift , and it stalls more frequently on a hot or cold start. I'm at 2,750 miles now. Before I bring the bike out of hibernation, I intend on rechecking the valves and tb's. I'm also going to change the oil in the engine,trans and fd. That way I know whats in there. I had the dealer do the 600 mile only for warranty purposes. It was torture to let someone else work on a vehicle of mine.
    Hey Bob -

    Don't think the valves alter the sync that much. By only adjusting the throttle body this week, the bike went back to riding as smooth as glass.

    Consequently, that's why I asked the question.


    J.K.

    P.S. It was out of whack by three bars, per mechanic at Foothill's BMW.

  7. #7
    Rally Rat
    Join Date
    May 2003
    Location
    Akron, OH
    Posts
    109

    Sync'd at 3750??

    Hello all,

    Just a quick question..... Shouldn't the throttle bodies be in "sync" at all rpms? Why would they "sync" at one setting and not all the others? The cables done stretch at certain rpms and not others, so why the "sync'd at" thingies????? Not sure if it matters, but really would like to know.....

    Thanks, Jeff

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