Concours 1400 (C14) FAQ > Engine and Controls (Fuel, Ignition, Exhaust, Sensors and the like)
TB sync - can't balance left and right
Shawzy:
Attempting my first TB sync on 2008 C14 (14000km or 8750m).
Got the carbtune-pro and 90deg driver. Getting to that center adjustment screw is tough - never mind getting the rubber cap off #2. Fingers still bleeding.
My issue is that turning the center screw does not seem to balance left and right.
Readings before any adjustments @ 1100rpm fully warm:
1-2-3-4 : 27-28-26-24
After three full turns out of center screw @1100 rpm:
1-2-3-4 : 30-32-30-26
No matter what direction i turn the center screw, the difference in the highest value on each bank (in my case between #2 and #3) is always 2. I am sure i am on the screw as change does occur with each turn, just not the desired change.
I am bit nervous about continuing, for fear of backing the center screw right out (do not want to go there).
How 'exact' is exact, exactly? Should i be able to get #2 & #3 equal to each other or is there a deviation acceptable?
Shawzy:
Ok - for whatever reason I got things balanced. Walked away, took a break, went back and made a single turn in and bang, success.
On first attempt I must have had the c14 idling for 15-20minutes trying to get that center screw, I kept checking she stayed at 1100rpm and adjusted as needed, not sure if this contributed to my issue or not.
All of my readings are now on the high side, ie: 29-30-30-27. I will attempt bleeder screw adjustment to get them in range (25+/-1).
Shawzy:
I need someone with a good understanding on the TB Sync to chime in here.
After syncing both left and right (ie. 1/2 with 3/4) all 4 of my tb's were not in spec. They were all on the high side. The manual states to "balance 1 and 2" and then "3 and 4" with bleeder screws. Ok fine. Done. Still not in spec, all too high. Manual doesn't cover what to do next, so I assumed that adjusting each bleeder screw to bring down each tb into spec was the next step.
This got me thinking - why do we bother with the centre screw in the first place, if we could use the bleeder screws to put all tB in sync with each other and within spec? Am i making this too complicated? Is the center screw meant as a 'gross adjuster' and the bleeders 'fine tune'?
If one can adjust all bleeder screws so all TB are bang on 250mmhg is this not the point - what am I missing?
Tactical_Mik:
:popcorn:
B.D.F.:
Yes, you could think of the balance screw between the two sets of throttle bodies as the 'course' adjustment and the air bleed screws as the 'fine' adjustment as that is sort of how it works out. To be honest, I do not know why there is a balance screw, as you mention all four T.B.'s could be synch'd with the air bleed screws.
I can't tell from your posts but after each adjustment you should tap the throttle just a little bit to bring the engine RPM up and especially, reset all the throttle body throttle plates against their respective stops. Just adjusting the balance screw and watching for change will not work very well. But you also have to be careful not to 'zing' the throttle too hard as there will be a strong vacuum generated when you close the throttle and you do not want to pull fluid (especially mercury if you have mercury 'sticks' (manometers) ) into the throttle bodies from the top of the manometer tubes. So a gentle tap on the throttle followed by perhaps 5 or 10 seconds to let everything settle down and stabilize and you will notice a change after each turn of the balance screw.
You also have to tap the throttle slightly when turning the individual air bleed screws just to reset all the vacuum levels in all the throttle bodies. Also this adjustment is tricky because as you adjust any one screw, the other three T.B.'s will change and the changes may NOT be the SAME for all three. So you are trying to hit a moving target. The method is to make small moves and generally move toward an even vacuum reading.
Not sure what Kawasaki recommends but I think it is something like 5 cm of mercury difference between all four. With some tweaking you should be able to get all of them within 2 cm of mercury, and perhaps a tad batter but 1 cm is a lot to ask for in my opinion. Note that each reading is really only good for one throttle setting, temperature, etc. because when something like the idle speed changes, so will the relative T.B. vacuum balance.
As far as the actual value of each vacuum reading, you cannot control that- physics does. At a given RPM and a given set of conditions (temp., air / fuel ratio, humidity, and several others) there will be a specific pressure drop across the throttle bodies where the throttle plates are restricting flow (and causing the engine to idle). You can adjust the ratios but not the total amount; if you raise one value, the other three will make a corresponding drop and the sum will be the same within a reasonable idling range. The actual vacuum value is more indicative of engine efficiency (volumetric efficiency) and condition and even that is not a very good way to measure in my opinion. My advice is to ignore the actual value as long as it is not a long way from the factory spec. say, 10 cm of mercury or more. Just balance the individual cylinders relative to each other and call it great; trying to hit a particular value is not going to work and will drive you crazy trying.
Glad to hear you made out OK with the whole thing. Tasks like this are not nearly as scientific as, say, balancing a wheel and tend to be a 'hocus pocus' or best result kind of adjustment like steering a boat on the water rather than a precision setting.
Brian
--- Quote from: Shawzy on May 28, 2011, 03:16:36 PM ---I need someone with a good understanding on the TB Sync to chime in here.
After syncing both left and right (ie. 1/2 with 3/4) all 4 of my tb's were not in spec. They were all on the high side. The manual states to "balance 1 and 2" and then "3 and 4" with bleeder screws. Ok fine. Done. Still not in spec, all too high. Manual doesn't cover what to do next, so I assumed that adjusting each bleeder screw to bring down each tb into spec was the next step.
This got me thinking - why do we bother with the centre screw in the first place, if we could use the bleeder screws to put all tB in sync with each other and within spec? Am i making this too complicated? Is the center screw meant as a 'gross adjuster' and the bleeders 'fine tune'?
If one can adjust all bleeder screws so all TB are bang on 250mmhg is this not the point - what am I missing?
--- End quote ---
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