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Twinmax zeroing problem


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I just resynched the T.B's on my 1100RT. My question is that everytime I shut the bike off between steps and to let it cool a bit (just to be on the safe side) my twin max would be off zero. Is this normal for the twinmax? I rezeroed the twinmax between each step, and kept going on the synch procedures. With the bike running I would make adjustments to bring everything to zero, but as soon as I shut off the bike the it would be off.

Am I being too anal or is there something I'm doing wrong?


This is the second time doing the T.B's in as many months, so I want to make sure I get it right this time, so I don't have to do it again right away.


All help would be appreciated.



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When you are zeroing the twinmax, bike is off, sensitivity should be all the way up, zero in, then turn sensitvity down, start bike, turn sensitvity back up (I personally go about 3/4 up, not full up) then start syncing.

Try using a house fan if front of the bike to help cool it rather than turning the bike off and on, higher temps can affect you sync. IMHO.

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I have had my Twinmax for several years now. I used it on several BMW bikes over the years and now on my '99 R1100S. I must admit I never checked if it is zero again after switching off. What I do is standard which is to zero the device with the bike not running and sensitivity set to max, ignition on and start ( of course with the engine already warmed-up earlier ) and adjust one of the brass screws to zero the twinmax at idle and adjusting one side of the cables for zeroing the twinmax at higher rpms and check the sync at other rpms. These " standard " procedures if followed would result in synchronised throttle vacuums over almost the entire rpm range. Sometimes it doesnt but with the Twinmax set at max sensitivity, we are talking about small discrepancies in vacuum which is not really noticeable when riding. I dont think there is a need to recheck if the Twinmax is back at zero with the bike engine off.... is there?? Have I missed something?? So far it has worked really well with all the airheads and now oilhead bikes that I have had. Plse enlighten.......

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There is a significant zero drift when using the Twinmax with the lamp connected. The circuit voltage is unregulated and the lamp draws a significant amount of power from the battery. As the battery voltage drops, the zero drifts. On my unit it would drift at least 2 full marks at max sensitivity over the course of about 5 minutes.

With the lamp disconnected, my TwinMax can be zeroed within about 5 seconds of being turned on. After that, the zero does not drift at max sensitivity for at least a half an hour, which is the longest I have ever needed to keep it on. There is also no drift when varing sensitivity between min & max.


As to whether or not a 2 mark drift at max sensitivity is significant enough to worry about, I'll leave to someone else to decide. For me it's easy to eliminate the drift so that my perfectionist streak is satisfied.

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So far it has worked really well with all the airheads and now oilhead bikes that I have had. Plse enlighten.......
You answered your own question!


If you don't want to cut the lamp connections make sure you turn the Twinmax on for at least 5 minutes before using it and don't turn it off until you are finished.

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OR......use a mercury manometer....easier, cheaper, no batteries, no zeroing and the manometer self calibrates to changes in barometric pressure (Heh-heh). If you are mercury conscious, make a manometer using clear plastic tubing and heavy transmission oil.....cheaper yet and, no batteries, no zeroing, self calibrates and adjusts to changes in barometric pressure....

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The twinmax is a bad implementation of a great idea.


Disconnect the lamp.

Rezero any time you touch the gain. In theory zeroing at peak gain would be best, but this is not the case with the twinmax.

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Thanks for the quick responses. It looks to me that maybe I'm being too anal and need to disconnect the light and all will be fine.

By the way I am using a fan and the temp never goes over 6 bars. Me being new to these oilheads, I am carefull about turning the bike off when I check the procedure to make sure I'm doing things right. I don't like having the bike running and taking a chance of melting anything.


Thanks again for the reply's

Dave thumbsup.gif

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I don't know how my operation of the TM differs from yours, but I have not had any problem with zero drift on my TM. FWIW.

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