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Old 09-08-2012, 10:13 PM   #104
Beastly Adventurer
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Joined: Sep 2004
Location: SanHo, NorCal
Oddometer: 1,242
Originally Posted by Poolside View Post
The link posted by BuilderBob covers the procedure. Based on the information on page 10 of that link, the VSS signal on the R12 is apparently an 'active low' signal. And needs a 'pull up resistor' in order to be a useable signal.

That all sounds perfectly normal. Except I would try using a 1/4 watt 1K or 2.2K resistor. A 300 ohm resistor seems like too low a value for a typical pull up resistor. Send me a PM if you would like to discuss it more detail.

This post here is probably the best post in the thread:

Summary of the above post. Mounting the Rostra Cruise on a R12GS:
1. Convert R12GS throttle grip to a 'twin throttle cable system' using two stock R12GS cables and the throttle drum from a 1300GT. One throttle cable connects to the Bowden box as it normally would. The new 'second' throttle cable connects to the Rostra unit.
2. The Rostra unit is equipped with has a throttle cable sticking out the side. Remove that cable and make an aluminum adapter to go from the Rostra unit to the new 'second' GS throttle cable.
3. Cut the 'cable ferrule' off the new 'second' GS throttle cable and solder on a new cable ferrule in order to achieve the desired inner cable length, and fit the cable to the Rostra unit.
4. The three pin plug under the beak contains a VSS signal. The blue w/green stripe works on the Rostra Cruise with the 6400 pulses per mile setting.

Presumably the pull up resistor mentioned above is required in step 4.

Yes, all of this information is excellent. Thanks for the pull-up resistor info Jim. I spent quite a bit of time trying to get that signal to work and ended up throwing up my hands and going with the coil signal. The required 12v is right there on the same connector...

About the other post, it looks to me like Dede used way more than just a K13 throttle drum. He's got a dual cable throttle housing that looks like it's from a K13 but the interface to the right side switch assembly needs quite a bit of modification to work on the R12GS bars. Looking at the pic he's got in his post, there's an intermediate aluminum part to make the GS switch bracket mate up. I'll send him a PM for more detail. Being able to run a dual cable throttle assembly is HUGE...
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