How i solved rosta cruise speed bleed down and excesive speed surging problems.

[davidgylland]

How i solved rostra cruise speed bleed down and excesive speed surging problems.

I recently installed rostra cruise and i had two major issues to solve. I search the web excessively and did not seem to get any real answers. So i would like to make this post so hopefully others will benefit from my pain. Lol. I have a Rostra electric cruise on a 2007 st1300 , i used a w2 pulse tracker to buffer and divide the vehicle speed sensor output.

1. first problem was that the cruise control would engage however the speed would gradually bleed down .
My fix for this was to configure the dip switches so that it wa set up for 15000 pulses per km and of curse to adjust the divder accordingly.
This for what ever reason solved the speed bleed down problem originally it was set to 38600 m/24000km setting.

2.next issue was that the bike had excesive surging combined with the fact that it alwas seemed to engage at a speed lower then the set speed. Then surge its way up to the commanded / set speed.

Played with may combinations of settings but finally settled on changing the engine set up timer to 8 cylinder high and this seemed to help alot. However it did not feel like it should . I turned my attention to the throttle set up original i used a chain bead set up,to compensation for the differance in cable travel. But i could not help but wonder if this was the main issue. I imagined it to be the same as a auto pilot with a lose elevator servo cable which would of course cause porpoising. So i fabricated a throttle leaver out of steel being very careful to make notched hole to match the throttle body shaft. The result was successful and i now have a very smooth cruise contol. Hope this helps others see attached photos, one shows previous install two shows the fix throttle close and open. P.S after throttle chage i did reselect 4 cylinder low.
My dip settings are. 001110100100.

 

[klwinter2]

David.. Can I talk to you about this fix?? Kenneth

 

[Larry Fine]

Ken, his post is over 2.5 years, but I may be able to help you.

 

[klwinter2]

Thanks for responding... I have just finished installing a rostra cruise control on my Honda Africa twin..
Today was the first ride.. I was excited it worked at all..

But I am having similar issues that you described.

I have tried Many DIP combinations.. But still the surging continues..

Questions:
1. I have already made an extended throttle arm on the throttle body.. This was needed to compensate for throttle pull length difference.
I wonder if it should be longer to make throttle pull smoother???

2. I am reading the VS sensor on the transmission.. I have no idea what the pulse rate is.. I can not find spec anywhere. I have the DIP settings on 38,600 max.
I wonder if I need to get the pulse divider or all a remote pick up like you did?
My bike is a 2016 Honda Africa twin.
How did you figure out the PPM for your machine?

Thanks for your input!!

Kenneth Winter
East TN

 

[Larry Fine]

Ken, I'm not the original poster. I have an 1100, not a 1300, but I can tell you what I do know. (Wiring is really my thing.)

With the Rostra 250-1223 unit, the beaded chain is not needed, because the cable can be pushed back toward the servo.

There are 1300 users here who can tell you the bike's pulse-per-mile count and the best frequency-divider setting to use.

The switch settings tell the unit your vehicle's power-to-weight ratio. Start with 8-cylinder high and low or medium gain.

 

[klwinter2]

With the Rostra 250-1223 unit, the beaded chain is not needed, because the cable can be pushed back toward the servo.

I dont understand what you are saying here?
Cable or sheath?
How to push?

 

[kiltman]

With the Rostra 250-1223 unit, the beaded chain is not needed, because the cable can be pushed back toward the servo.

I dont understand what you are saying here?
Cable or sheath?
How to push?

The black plastic nozzle that comes out of the servo, inside it the cable can move inside it to accommodate the normal travel of the throttle cable when the cruise is not activated.
In theory you don’t need to have beads on the end that is attached to your throttle body.
What you also have to insure is that the servo is secured to a frame member so that it DOESN’T move at all. Any movement on the servo will cause the cruise to hunt for the speed ...it will surge then drop then surge etc.
The Rostra needs to travel 41 mm in an arc off the bellcrank. What needs to happen is figure out how far your throttle cable goes from lock to lock. On the 1100 the travel is 31mm so the arm I had to put on was a radius of 2.25” to get the 41mm travel.

 

[Larry Fine]

The Rostra manuals are a mix of generic and model-specific instructions. The beaded chain is used with older models, like the vacuum-operated units, so the servo cable's inner wire doesn't bend or bunch up when the CC is off.

On my Nighthawk, I adjusted the cable using the outer housing clamp so there was next to zero slack, just like I prefer with my throttle cables. Too much slack causes slow throttle response, which helps cause speed hunting.

The throttle cable attachment on the Nighthawk was easy with the wire loop, because the cable wheel is made from stamped steel. The one on the ST is a solid wheel, so some form of adaptation is necessary. I'm still exploring options.

 

[Sadlsor]

<SNIP>
The throttle cable attachment on the Nighthawk was easy with the wire loop, because the cable wheel is made from stamped steel. The one on the ST is a solid wheel, so some form of adaptation is necessary. I'm still exploring options.

Please keep us posted, Larry.
The original Rostra thread was begun about 15 years ago, with not a lot of new posts. I have PM'd a couple names I found there, to establish reliability over time, and it seems for the most part, that a solid initial installation and proper tuning results in a fairly hassle-free upgrade.
While not an immediate project, I plan to add this in the next year to my 1300, and pair it to a proper GoldWing cruise control pod throttle-side for a sano install.

 

[Larry Fine]

Please keep us posted, Larry.

For the throttle cable, the choices I've explored are, in no particular order:

The MCCruise dual-drum interface

A generic dual-carb cable splitter

Replacing the throttle return cable

The popular bar-on-the-carb-wheel

Adding a second carb cable wheel


For the controller:

A GoldWing right-side switch pod

The TrailTech 8500-RS switch pod

An ST-police right-side switch pod

Buying or making a CC switch pod

 

[Sadlsor]

My understanding (*limited* understanding, that is) seems that the "cam" or modified interface from the throttle linkage to the actual cruise control box is the primary obstacle to smooth, surge-free speed setting.
This is after, or in conjunction with, the pulse-thingie (pulse-per-mile?) and the dip switch settings. I haven't reviewed the thread in a few weeks but the custom hardware connecting the throttle to the box seems to vary between installers, and that the bead chain is the least desirable / efficient.
But I'm just virtually bloviating around our digital campfire, as I will have to reread it before I have the complete grasp of the issues.

 

[kiltman]

and that the bead chain is the least desirable / efficient.

Yes and no.
First off I would disqualify the McCruise interface with the Rostra. Tony of McCruise explained, because of the travel required by the Rostra exceeds what the interface can deal with, and as a result the surging/hunting becomes an issue. The McCruise interface deals 1 for 1 31mm of travel and their servo does that travel. The Rostra requires 41!
The other thing to consider, and this is where the bead chain comes into play, is ideally you need a good sweeping curve of the cruise cable to the throttle with the Rostra set-up, so the cable inside the sheath will not bind allowing the cable to slide into the servo. If there is any binding in the cable the bead chain will allow just enough flex for the throttle not to bind. I have just one bead. This works out best for me.
I have to have my servo in the tail section because I have an ABS unit and there are computers and pumps in the front fairing preventing me to locate the servo there. If the cruise cable was two inches longer the tail location would work better. I contacted Rostra to see if longer cables were available and they are not. there standard replacement cable is $75! I suppose one could make a new cable but you have to also incorporate the nose cone that houses the cable and attaches to the servo.

 

[Larry Fine]

Well, in my opinion, the CC doesn't need to open the throttle the last 10mm of travel for realistic operation. I certainly wouldn't want it to have that much control over the bike, and the STs have more than enough torque to not need it.

As for a simple way to deal with bike cable vs servo cable travel differences, there's the Rostra 250-4198, aka the Throttle Multiplier. Not only can it compensate up or down in travel, it can also be used to extend a too-short servo cable.

 

[kiltman]

there's the Rostra 250-4198, aka the Throttle Multiplier. Not only can it compensate up or down in travel,

I was interested in that and had sent you a link via PM awhile back. At one point it was unavailable.... is back in inventory?

 

[Larry Fine]

PM sent.

 

[Sadlsor]

I was interested in that and had sent you a link via PM awhile back. At one point it was unavailable.... is back in inventory?

Amazon - $60 USD and $6 shipping:
Click here for Amazon listing

 

[kiltman]

Amazon - $60 USD and $6 shipping:
Click here for Amazon listing

The shipping price is $16-$80 to Canada plus exchange. I’m good with the system now. Thanks. Larry sent me a link as well

 

[rwthomas1]

Oh boy, questions for Kiltman and Larry, and anyone else who wants to chime in!

Since I have the bike apart and the carbs off, I figured I'd add the "arm" to the throttle cable wheel. I may not do the Rostra immediately, but now is the time to get the hard part done. I have looked at numerous posts, and Kiltmans instructions, and there are some discrepancies in how long the arm should be. According to Kiltman, and everyone else, the Rostra has 41mm of cable travel. That works out to roughly 1.6 inches.

I made an arm based on the numbers in the Kiltman instructions, drilled tapped and installed it, then started taking measurements.

According to the Kiltman instructions, a radius of 2.25" was used to get the 41mm/ 1.6". Well, 2.25" radius gets more like 2.5" of throttle travel measuring stop to stop on the carb. Hmmm, confusing. Now, maybe this works as in the Rostra can only pull 1.6" of the possible 2.5" of travel available it would never have more than maybe 60% throttle authority. Additionally, using all the Rostra travel for just 60% of the available throttle travel should made for fine, smooth control within that range.

I can see how there was issues with the Rostra directly connected to the throttle cable wheel. Just a guess but I think the Rostra would actually have excess travel in that location. As in 100% of throttle travel is only 80% of Rostra total. Things would probably get weird.

So the question is, is my fabricated arm too long, too short, or just right? I have a suspicion that it may do better a bit shorter, say with 100% Rostra travel for 70% of available throttle. I'd hate to not have enough travel to maintain speed when loaded and climbing a grade on the highway.

Thoughts?

Thanks, RT

 

[Larry Fine]

I can see how there was issues with the Rostra directly connected to the throttle cable wheel. Just a guess but I think the Rostra would actually have excess travel in that location. As in 100% of throttle travel is only 80% of Rostra total. Things would probably get weird.

The aggressiveness of the servo is fully adjustable with the DIP switch settings. On my Nighthawk, I put the loop cable end on the servo cable directly onto the throttle cable barrel, and I clamped the servo cable housing to the throttle cable housing.

 

[kiltman]

Guilty of doing the math wrong, I based the length of the arm from a member here had done. The bottom line is that it does work. I’ve been able to set the cruise at 30 mph - 80mph and no issues. If you wish to make the arm shorter it should be ok.