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Thread: 09' R1200RT TB Sync

  1. #1
    xdriver
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    09' R1200RT TB Sync

    I had a GS of the same year prior to this bike, and did my TB sync with little issue. With this one, I just can't seem to get it. Bike is warm, Twin Max calibrated, Idle at max sensitivity, Then adjust my way up to 4000 RPM stopping at 2K and 3K on the way. Check it again, before I tighten everything down and all is well.

    When i tighten down the nuts, I use the two number 10's and I swear that top curl nut does not move. Then, when I start up again and recheck on the TM, it's off again. Not much, maybe .25 +/- on one side. Then I try again, and it all repeats. I spent all morning on this simple task. Am I just trying to hard to make it perfect?

    Also, I never ran my GS at the speeds I run this RT (80-90 and 4500RPM+ plus at cruise), but I just seem to get this buzz in my feet, and a very slight vibe in the bars that I don't recall on my GS. I know I should feel this bike, but how much, and yes I know that's subjective? Again, am I just trying too hard and being hyper sensitive to any vibe?

    On two previous TB syncs on this bike, I did do the valves first. This one was just a TB sync due to above mentioned vibes.

    Thanks

  2. #2
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    Vibes mean it isn't right. Do the valves first and then the TB sync. I don't like the twin max but know others swear by it. I use the carb tune/have done at least 60 TB's on BMW RT's and GS's and never had vibes after.
    Marty Hill
    12 GS black/Boxer Cup Replika

    ride till you can't

  3. #3
    xdriver
    Guest
    Thanks Marty. I think you're right, and I think what's happening are one of two things.

    A)I tighten that bottom nut, and it pulls just enough on the cable to throw it off some, and I need to try and compensate for that.

    B)The Twin Max sits on the seat of the bike while I do the sync, and the vibrations running through the twin max from the seat are making the needle give me erroneous readings. When I check it after the sync, it's always in my hand, so it's steady.

    Guess I'll pull the tupperware again and give it another shot.

  4. #4
    Polarbear Polarbear's Avatar
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    Very sensative;

    Mine too, as you describe. IF you don't hold your nose just right, stand just perfectly correct, you get this phenom. I've been using the TM for a very long time and still like it, but practice is an understatement with these devices. Once set, I rarely ever have to go back in though and I mean sometimes a year or more, no adjusts. That nut tightening on the TBs is a bugger and usually a reepat a few times to nail it, dead on. Randy

  5. #5
    A bozo on the bus deilenberger's Avatar
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    Actually - even though I wrote the DIY on balancing the TB's - aside from doing it for that DIY, I've never adjusted the balance on mine.

    Once the valves are dead-nutz on (even on each cylinder and even cylinder to cylinder) the balance has been pefect, even on max sensitivity on the TwinMax. The bike currently has 52,000 miles. I suspect many people who adjust the balance - simply are correcting for a not perfect valve adjustment.

    A few things I may have left out on the DIY..

    - Leave the Twinmax on for about 5 minutes before trying to balance anything. It drifts a bit from a cold start.

    - Zero it at max sensitivity, then turn it down to minimum before starting the engine.

    - Once the engine is started - don't adjust anything at idle. The steppers do wander relative to each other at idle. Wait until the steppers seem to be in sync, and turn the sensitivity up. As the steppers settle down (engine warmed up) - increase the sensitivity. You only want to do this when the steppers are giving what appears to be an even vacuum at idle.*

    - Once the steppers are settled down - then open the throttle to 2,000-2,200 RPM. The steppers are now locked together in the same ratio as they were at idle. And they track that way at different openings. They are basically out of the equation for balance - but they can offset the reading slightly if they were offset at idle (BMW's instructions alude to this - not too clearly..)

    - That's when you balance the TBs. And I do it at fairly low RPM (around 2-2,200 RPM) since that's where it's most sensitive.

    If you get it right at that point - then reving the engine to higher RPMs - the balance should remain good.

    Checked mine the other day - and it was perfect from 2,000-6,000 RPM at max sensitivity on the TwinMax. That was without adjusting anything - I had just adjusted the valves and put in new plugs.

    * = This is where the "lock steppers" TB balance function on the GS-911 will come in handy. It sets the steppers to a uniform opening and then locks them there. The GS-911 "zero the steppers" function might be useful IF you never let the full startup procedure complete on your bike. If you do - when you turn the key on - before starting the engine - the instruments go to max values then back to zero, and the steppers do a self-set-zero function. It takes about 10 seconds for that function to complete.. The GS-911 is also handy since it won't let you do the balance function until the engine is fully warmed (someplace around 170F on oil temperature.) Doing it before the engine is fully warmed up will give inaccurate results.

    Oh - my bike felt wonderful after doing the valve adjustment. They were almost right on - but the exhausts were slightly different side to side (less then 0.001", but enough that I could feel the difference with the feelers, using a GO-NO-GO feeler sequence.) It really does make a difference (which makes me wonder if the new OHC engines can be tuned as well since the spheres used to adjust the valves only come in descrete steps..)
    Don Eilenberger http://www.eilenberger.net
    Spring Lk Heights NJ NJ Shore BMW Riders New Sweden BMW Riders
    '07 R1200R (current ride) and some bimmers.. and a Porsche

  6. #6
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    Take a good look at all your hose connections and make sure they are all clean/tight. Even a trivial leak will mess up a balance device.

    BTW, for tools these days- take a look at the Harmonizer. Sold over at the adv site.

    I use a TwinMax with no issue and agree with Don- get it right and it stays. I don't check valves and synch every 6K any more. No need to do it that often.

  7. #7
    Polarbear Polarbear's Avatar
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    Agreed:)

    Valves are a major player indeed, as airflow is what the TMs are reading and the slightest off valve set is always suspect. Engine breathes in and out via the valves. I set my TBs without checking my valves the other day. Why, you ask. Just to do it and I was and always am looking to improve my mpg's. The GSA has been suffering lately in this department, mpg's. I am a lifelong wrench on bikes, so I usually know mine quite well, in and out. Bike runs perfect. My valve check is coming again soon enough, before depart to Sedalia Rally. I've been doing'em every 6000+, sometimes to 8000m intervals and they rarely change like you said above. Ever so slight adjusts at best. FYI; my mpg's have been 35-37 for some time now and it has dropped about 10%+ from my best of 40+. Our gasolines are changing. Randy

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