Rostra electronic cruise control installation
I’ve been installing a Rostra electronic cruise control on my 06 Boulevard M50 and am essentially done.
This was not a quick or easy installation. I spend the better part of several days on this. I would not recommend this to less than an accomplished mechanic. The attachment to the throttle must be safe, secure, and reliable to avoid a potential disaster. I’m not offering this as a how-to or instructions; rather just showing what I did. BTW while Rostra acknowledges “creative” installations on motorcycles and ATVs, they do not support such installations, so you are on your own.
The most difficult part was the throttle connection. The kit provides a few means of attachment to the throttle, but I did not use them. I used a metal R/C clevis with a keeper, a shaft, and a custom bracket with guide. I drilled a hole in the tab stop on the throttle butterfly – this tab rests against the idle screw at closed throttle and a stop at WOT. By placing the hole for the clevis near the end of this tab, I was able to get the required 1-5/8” of linear travel required as described in the Rostra instructions.
The throttle tab needed to be bent a bit for smooth operation. I ended up building a special tool to do this, to avoid having to remove the throttle body from the bike. This alone took several hours of trial and error.
The photos show the throttle closed and at WOT with the Rostra cable attached. As the throttle is opened, the cable slides back into the cable sheath. The Rostra model that I used, 250-1223, employs what Rostra calls “lost motion”, so this is the proper way to make the throttle connection. In cruise mode the Rostra of course pulls the cable.
Next most difficult was placing and mounting the servo/control unit. I had already used the space on the right side of the bike near the ECU (not sure the Rostra would fit there anyway). I found barely sufficient space behind the tool kit box on the left side. I simply bent the Rostra-supplied mount and fabricated an adapter out of HDPE to bolt the mount to the frame. Sounds simple, but I spend several hours determining that this was the right location and getting the bends just right.
I had to cut away a portion of the tool box, and then close it up with sheet aluminum using pop rivets to fasten and RTV to seal. There is still plenty of room for tools, as the cover itself contains significant volume.
The cable was routed up the frame to the right and looped around to the left.
Electrical connections were fairly straightforward. I used the auxiliary power connection in the headlight bucket. The required Vehicle Speed Sensor (VSS) signal is at the headlamp, as is the clutch switch. The latter is connected to the Neutral Safety Rostra input, so that squeezing the clutch disengages cruise control, as does brake application. I used a relay to make the required connection to the LED brake light per Rostra instructions.
I did not use a Rostra control switch, as they don’t make one for motorcycles. I used a momentary on – off – momentary on toggle switch, mounted in place of the hazard lights switch. (I didn’t think that switch was too useful. A replacement could easily be connected and mounted at the back of its original location). I did not use an on-off switch for the cruise itself, as one is not really needed. You use the toggle switch to engage, and tap the brakes or squeeze the clutch to disengage.
Right now it is working quite well, but I am still fine-tuning the Rostra setup DIP switches, particularly the settings for “Gain” and “Engine/Setup Timer”. These affect the response to hills and load, and how much or little the cruise drops speed and recovers. I’m happy to use the system as-is, but will be playing with it over the next few days to see if I can smooth the response out a bit.
2006 blue M50
2019 Honda Super Cub C125
1983 Wetbike (sold)
Last edited by DickB; 03-07-2019 at 07:05 PM.