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#469673 - 04/27/09 12:36 PM Question on throttle body sync on R1200rt.
palani Offline
Newer Member

Registered: 08/20/06
Posts: 32
Loc: Lake Orion, MI
After completing the valve job on my R1200rt I proceeded to do throttle body sync. As simple as it may sound I am confused. I followed JVB instructions to do this. I have not did not make any changes to the throttle cables or disconnect the stepper motor. I just wanted to get a baseline read out.

This is the procedure I followed.
1) After the valve adjustment I ran the engine for about 10 minutes.
2) I used the twin max hose and plugged it onto the vacuum hose nipple on the engine heads. Here were I had my first issue. The hose from twinmax fits very loosely on the vacuum nipple (especially on the right side of the engine). And depending on how the hose is moved/wiggle the reading varies. Did others have the same problem?
What I did for this issue was use a zip tie to tighten (I took care not to over tighten the hose the vacuum nipple). I could still pull the hose out from the nipple without the need to cutting the zip tie. I made it hand tight.

3) Next with the engine shut off, I moved the twin max knob to high sensitivity setting and centered the zero as suggested by JVB. I started the engine and let it run at idle. The needle was swinging back and forth between 1-2 -3 on the A side. I had plugged the hose from twin max side A to the right side of the engine and B to the left side of the engine where the hose attaches to the carbon canister.
According the JVB at idle the needle should be swinging at 1-0-1. Prior to zip tie the end of the hose the reading was 1-2-3 on the B side.
I am not sure if the reading is correct at idle? Any insight
4) I can manually center the needle between 1-0-1 when the engine is running at idle. Then I raise the rpm to 2000, 3000 and 4000 and the reading shows that I am of the center of zero towards the B (0-1). I did not make any changes to the throttle cable.
5) But now when I shut the engine off and with the twin max still in on position the needle is pointing at 1 on the B-side.

Am I doing something wrong that gives me all these varying read outs or do I have a problem with my idle? Please advice.

#469694 - 04/27/09 01:41 PM Re: Question on throttle body sync on R1200rt. [Re: palani]
Twisty1 Offline

Registered: 06/25/06
Posts: 5799
Loc: Mi
palani, personally I dont use a Twin Max so hopefully someone familiar with TwinMax operation will help you out with that part..

A couple of thoughts here though..

1)- For ANY TBI balancing equipment.. U-tube,, or gauges to function with any sort of accuracy the hoses MUST fit tight with absolutely no leakage at any of the attachment points or joints.. I would suggest that you either buy some short pieces of correct fitting vacuum tubing & some plastic connectors then make your TwinMax fit the TBI nipples correctly (tie straps are a very poor way to make hoses fit as they dont fit tightly all the way around the hose due to the pull through latch).. OR buy some very small O rings & place those on/over the vacuum hose at the TBI nipples as that will force the vacuum hose to shrink tightly on the nipple connection..

2)- Also,, buy a vacuum tee so you can hook both TwinMax hoses to the same side TBI.. That will allow you to see how accurate the TwinMax is on each side.. If both TwinMax hoses are hooked to the SAME TBI they had better read exactly the same reading or you have issues with your instrument or its calibration.. Once you are sure both sides of the TwinMax read the EXACT same when hooked to one TBI vacuum source then you can hook it to both TBIs & be assured it will be accurate..


Only a Motorcyclist knows why a dog rides with his head out the car window

#469697 - 04/27/09 01:49 PM Re: Question on throttle body sync on R1200rt. [Re: palani]
hopz Offline

Registered: 08/21/05
Posts: 3717
Loc: Colorado Springs, CO
First of all, update your profile so we know where you are.

Next, you are misreading the JVB directions. what you have described is the incorrect process.

The Twinmax vacuum hoses should fit fairly tight over the nipples. There is an adapter hose available to accomplish this.

Install fresh battery in the TwinMax.
Fit the hoses to the nipples, warm up the bike, set sensitivity low,
Start the bike, at idle read the meter as you turn up the sensitivity.
Run RPM up to 3500 or so (more or less as you desire) read the meter.
Adjust the right hand throttle cable in or out as necessary to center the needle while at the desired RPM.
Lock down the cable. Re-test, re-adjust till you get it correct. Done.
<---- (That's not it) 2014 R1200RT-W

As Woody Guthrie says, Left wing, right wing, chicken wing.I keep my mind open. Whatever you believe, its all a mystery in the end.

#469704 - 04/27/09 02:07 PM Re: Question on throttle body sync on R1200rt. [Re: hopz]
markgoodrich Offline

Registered: 02/04/07
Posts: 3311
Loc: Austin, TX
RL Motorcycles sells the Twinmax with hose adapter and smaller-diameter hose specifically for the BMW. Perhaps you could call them and purchase the adapters. Very nice people.
2012 K1600GT

#469715 - 04/27/09 02:35 PM Re: Question on throttle body sync on R1200rt. [Re: palani]
SageRider Offline

Registered: 01/16/02
Posts: 8287
Loc: Minden, Nevada
When I bought my Twinmax, it came with clear nylon tubes and black rubber tubing for the end, connected by a plastic vacuum coupler.
The rubber tubes were too big for the BMW ports, and the couplers leaked anyways. I replaced all the stock tubing with a smaller diameter (don't remember size) that I was able to get at the local auto parts store.
In addition, disconnecting the power to the meter light inside the Twinmax will reduce meter zero drift to nothing.

If you doubt the meter's accuracy, connect both tubes with a vacuum tee, then pull a vacuum. Meter should read zero (as set on unit) with or without vacuum applied.

Edited by SageRider (04/27/09 02:36 PM)
2010 Unrally IX Sierra Adventures Co-Chair
KE6GYC 2M/440
'12 F800-GS Trophy: (dearly departed)
'06 R1200-RT, Piedmont RED! (dearly departed)
'99 R1100-RT (dearly departed)
Minden, Nevada

#469730 - 04/27/09 03:22 PM Re: Question on throttle body sync on R1200rt. [Re: SageRider]
Redbrick Offline

Registered: 06/05/05
Posts: 2570
Loc: Santa Paula CA
I used 1/8" ID plastic tubing to size the Twin Max hoses down to a tight fitting size in both the hoses and on the nipples....Cost about two bits at the local hardware store.......


"It's not the arrival, it's how you got there."

'05 R1200RT (red, of course)

#470241 - 04/28/09 07:39 PM Re: Question on throttle body sync on R1200rt. [Re: Redbrick]
PlaneGeek Offline
Newer Member

Registered: 07/08/08
Posts: 12
Loc: Salem, OR
Originally Posted By: Redbrick
I used 1/8" ID plastic tubing to size the Twin Max hoses down to a tight fitting size in both the hoses and on the nipples....Cost about two bits at the local hardware store.......

Good idea... Mine did not come with the adapters either...
Jeff K.
Salem, OR
'08 Silver R1200RT