HEXHEAD Tech - R1200XX - Throttle Body Sync, all years

[deilenberger]

GOAL: This thread will discuss balancing or sync'ing the dual throttle bodies BMW uses on their opposed twin Hexhead motorcycles. It involves the use of some specific tools - and assumes some level of intelligence on the part of the reader.

The articles, posts and comments in this tech section are posted by individual members and reflect their personal thoughts and experiences with repairing, maintaining, and generally working on motorcycles. This information may require specific knowledge and skills, may or may not be correct or current to model.

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PLEASE PRINT AND READ ALL THE INSTRUCTIONS BEFORE BEGINNING! Make sure you understand what is being said, and what the concept is. If it's confusing, or I haven't explained something well - feel free to PM me, I'll try to clear it up, and it may help make the DIY better!

TOOLS NEEDED:

• TwinMax - Electronic differential balance tool - available from various vendors: http://www.google.com/search?sourcei...S221&q=twinmax - Approx. cost - a bit over $100.
• 2 x 10mm open-end wrenches.
• Large fan to use for cooling the engine while doing the adjustment.

TwinMax:

[deilenberger]

BIKE PREPARATION:

• In order to do the balance - or even the balance check, one must first be certain the valves are correctly adjusted. This is vital. Misadjusted valves will throw off the Throttle-Body sync/balance. If you haven't done the valve check/adjustment, please see:
  http://www.bmwmoa.org/forum/showthread.php?t=35445
  
  
• You also need to have access to the two throttle bodies. On some bikes they are easily accessible (R1200R, R1200GS), other bikes less so. On bikes like the R1200RT it makes sense to do this check/adjustment as part of the regular service where the plastic body panels will be removed. For removing the body panels on a Hexhead RT - see:
  http://www.bmwmoa.org/forum/showthread.php?t=35262
  
  
• The bike also must be warmed to normal operating temperatures. Since the bike will be run in a stationary position for a short period of time, it may be worthwhile to use a large fan to provide some cooling air over the engine.
  
  
• Place your fan where it will blow directly onto the engine/oil-cooler assembly. Since you'll be running the engine for a short time with the bike stationary - we need to have some air moving over it so it won't overheat.
  

Once again - I'll repeat - do NOT continue in this operation unless you are absolutely certain your valves are correctly adjusted!

[deilenberger]

TOOL PREPARATION:

Seems like not much to prepare - but - even though the TwinMax is a solid state device, there is a bit of learning to do to use it correctly.

First - check your TwinMax and see if it has short small diameter extensions to the primary hoses on it. If not - you're going to need these. The connections on the hexhead throttle bodies are smaller than the ID of the long tubing on the TwinMax. Some of the dealers who sell it - if it's being sold for use with a BMW - include reducing nipples and some short lengths of hose that will fit the BMW throttle-bodies.

If you don't have the reducing hoses - you might contact the vendor who sold you the TwinMax, or visit your local pet store. Turns out that fishtanks use tubing of all sizes to connect up various air operated accessories, and reducing nipples to connect different size hoses are quite common. You may also find these nipples at the big rotating "stuff" rack in your local autoparts store. What you want to end up with is tubing with an ID of about 1/8" - which will comfortably fit over and most importantly - seal to the Throttle-Body nipples.

Next - you want to make sure your TwinMax has a fresh battery in it and turn it on and calibrate it.

Calibrating the TwinMax:

1. Turn the SENSITIVITY knob fully counterclockwise (DOWN.
2. Turn the TwinMax on - and center the needle on the scale using the ZERO knob.
3. Walk away for a few minutes. Despite it being solid-state, there is some settling time on the TwinMax where it will tend to drift around for a minute or so. Give it a chance to stabilize.
4. Keeping the needle centered on "0" using the ZERO knob, start increasing the SENSITIVITY. You want to be able to turn the SENSITIVITY to max with the needle remaining at "0".
5. Once this is done, turn the SENSITIVITY fully counterclockwise again - leaving the TwinMax ON. Don't touch the ZERO adjustment!

You're now set to use the TwinMax!

[deilenberger]

The TwinMax with the reducing nipple (yellow box) and reduced diameter hoses (green box):

[deilenberger]

CONNECTING TO THE LEFT (clutch side) THROTTLE BODY:

The connection points on the throttle bodies are located on the top of each body. On the clutch side - you'll find a hose attached to the nipple. This hose goes to a purge valve that connects to the charcoal canister on your bike. It's shown in the photo below.

With the engine OFF

1. Remove the tubing*.
2. Connect one of the hoses from the TwinMax to this fitting.

* - if your bike is not a US model, it may not use the charcoal canister, or your US bike may have had it removed. In that case - there will be no factory hose connecting to this fitting - it will be capped just like the one on the throttle side.

[deilenberger]

CONNECTING TO THE RIGHT (throttle side) THROTTLE BODY:

Again, the fitting is easily located on the throttle body:

1. Remove the rubber cap - put it where you'll find it later (they do like to go missing.)
2. Connect the other hose from the TwinMax to this fitting.