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Vacuum boost required for aftermarket cruise control?


Christo

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I'm planning on installing an aftermarket cruise control kit on my R1100RS. I'm going to use a vacuum powered cruise control system very similar to the Audiovox CCS100 kit, which is intended for automobiles.

 

my question is, is there anyone with experience installing these kits and *not* installing an auxiliary vacuum boost canister? I have installed several of these kits on cars, with and without a vacuum boost canister. I know firsthand how the auxiliary vacuum canister boosts the strength and responsiveness of the actuator. But at least for cars, a vacuum boost canister is not needed because there is sufficient vacuum coming from the engine.

 

Since this motorcycle has less available vacuum then a car, would this mean that the actuator could not work properly, like say up hills, without an auxiliary vacuum boost canister?

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Evening SnakePlisskin

 

I think that ultimately you will need a vacuum storage container.

 

Your 2 cyl BMW boxer has a few things that aren't the best for vacuum operated devices.--The engine only has 2 cylinders with a 360° firing order so the vacuum pulses are quite abrupt & spaced far apart, the TB's have rather large openings for the engine displacement so maintaining enough vacuum to operate the vacuum servo will be iffy when climbing hills, & the camshafts are fairly aggressive so the lower RPM vacuum will be even lower & more ragged. (multi cylinder engines produce a much more even vacuum than the BMW 2 cylinder does)

 

Not only should you probably install some sort of vacuum container or containers but you also need a one way check valve between the intake manifolds & the vacuum container(s).

 

You don't need a commercial vacuum container as you can make your own to fit in about any available spaces on the bike (Campbells soup cans work good as well as flat round tuna fish cans (just solder a vacuum fitting into the can). Then put a vacuum check valve between the engine & the vacuum cans.

 

You can t-r-y without a vacuum storage container but my guess is you will end up with one (or multiples if space is limited).

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http://www.ibmwr.org/ktech/k11cruise/k11cruiseInstall.shtml

 

Use this link and read how to make a vacuum boost reserve. This is the one that I made in about 1/2 hour and 7 dollars in parts. It is a 7" piece of 1 1/2 inch PVC, 2 end caps, a 1 way vacuum valve,and 1 tee and some RVT sealant .Yes I cut mine 1 inch shorter so it would fit in the tail section.

In this write up he tells you how to build this very unit. It works for me as this is the 2nd unit that I have hooked up.

The one thing that I have found with the Audio vox unit I used is you have to be turning at least 3000 RPM for the unit to engage and hold, so if you are running 50-55 keep it in 4th gear, If your at Highway speed in top gear its no problem holds great going up hill or down hill with no jerking just smooth and steady.

The unit seems to supply plenty of vacuum for my unit. I bought one of those ball units but it would not fit in the tail section of my R1100rt.

With the PVC unit I can still store my tool kit and the vacuum unit and the cruise unit all in the tail section of the bike.

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VACUUM RESERVE CANISTER

 

The vacuum reserve canister (VRC) is used to provide adequate vacuum for the cruise control servo unit. It uses the throttle body as a vacuum source and, via the vacuum check valve, stores up vacuum for the servo to use to pull the throttle cable.

 

You can also buy one of these at an auto parts store for about $10-15 but I decided to build my own so I could make one that would fit inside the left front of the main fairing body. If you decide to buy one, make sure you can return it if it doesn't fit inside the fairing or be prepared to mount it somewhere else like inside the tail cowl.

 

I used 8" of 2" diameter PVC tubing because that is the length that would easily fit inside the fairing It is mounted inside the fairing in front of the left "bucket." I used white PVC tubing but, in hindsight, would use black if possible since it is visible to the rider when mounted in the fairing. I suspect that the cruise control may actually work without the use of the vacuum canister so you might want to try the cruise without a VRC. If you do install the cruise control without a VRC, you'll want to put a vacuum check valve in the vacuum hose that goes from the throttle body to the cruise control servo unit.

 

VRC

 

I used epoxy for assembling the VRC as it's my permanent adhesive of choice. Cut an 8" length of 2" diameter PVC tubing. Sand the edges. Drill two holes as shown for the check valve and vacuum tee. There's a vacuum tee in the bags of installation miscellany that come with the cruise control. File the webbing from the right angles before gluing it and the check valve in place. Remember to glue the tee into place before gluing the end caps on. Make sure everything has an airtight seal. I used zip-ties to hold it in place inside the main fairing body in front of the left bucket.

 

Remove the little rubber cap from the #2 throttle body and run a length of vacuum hose from the throttle body to the check valve on the VRC. Route the vacuum hose so it doesn't get pinched when you put the gas tank back on. (You need to remove the tank to install the cruise control's throttle cable and power supply. If you don't know how to remove the gas tank, check your Clymer or Haynes manual.)

 

The vacuum hose from the "T" will go to the servo unit.

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Thanks DR for the technical comments. interesting to hear how the vacuum is produced and how it comes in quick pulses and may not be strong or steady enough to actuate the cruise control plunger. And I like your ideas using cans. I imagine they would be lighter and take up less room than some of the other methods. Thanks for the reminder about the check valve. Seems I had read something about that also.

 

Twinsig, I have looked into just about all cruise control devices with the throttlemeister being at my top end of the non-electronic options. I was contemplating the amount of work I was going to have to put into this project and so the mechanical methods started seeming more attractive. I should probably try an inexpensive alternative before I do anything else. I just can't get over the cool factor of having the electronic speed control.

 

njl4, thanks for the helpful information and links. Sounds like you've worked out all the kinks. I saw the write-ups on making the PVC vacuum chambers. I was just a little concerned that it would take a) more fabrication time, and b) more room in my trunk. Sounds like you knocked it out pretty quickly which is impressive, and still have room for your tools. and thanks for the tip about using the check valve even without a vacuum canister. I wouldn't have thought of that.

 

I had the idea of replacing my charcoal canister with a makeshift vacuum resevior, and just now after reading DR's suggestion, using the charcoal canister itself as the vacuum reservoir. Wouldn't that be a cool repurposing of space and materials. :grin:

 

njl4, did you ever ride the bike and test without the vacuum canister?

Also, were you not able to change the jumper settings on the servo unit to account for the lower number of ignition Pulses from the two cylinder engine? I know the Audiovox system was designed for a 4 cylinder engine at a minimum, but I was just wondering if you played with those jumper switches to get a lower speed engagement.

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I have played with these systems on a couple of bikes and was never really impressed even with them.

 

I have a Rostra electronic unit on my 1150RT and it operates as well as a factory cruise in my opinion.

 

You do need to use either a pulse splitter on the ABS signal or find a way to generate a pulse signal off the speedo cable.

 

Nasty install on these bikes, quadruple the time you think it will take.

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Boomer343, I hear you about the time involved. It's going to take some time. About the speed sensing, I was planning on getting the signal off the black wire to the ignition coil. Others have posted it that has worked for them and that is what I've used on the cars I've installed it on.

 

My biggest challenge is connecting the actuator cable to the throttle body. The actuator would be in the trunk, and in order to connect the cable to the throttle body and not rub on the crossover cable or any other brackets, I'd like to have the actuator cable pull vertically. To do this, I would have to fabricate a couple of brackets and a pulley. That would not be a five-minute job.

 

If anyone has pictures of how the throttle cable is attached, I'd love to see them.

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njl4, did you ever ride the bike and test without the vacuum canister?

Also, were you not able to change the jumper settings on the servo unit to account for the lower number of ignition Pulses from the two cylinder engine? I know the Audiovox system was designed for a 4 cylinder engine at a minimum, but I was just wondering if you played with those jumper switches to get a lower speed engagement.

 

 

Morning SnakePlisskin

 

In some respects the BMW 2 cylinder boxer is seen as a 4 cylinder as far as sparks per revolution go. Your BMW 2 cylinder uses a "Lost Spark" ignition system so it sparks on every piston up (not every other piston up like some of the older 4 cylinder engines with conventional ignition systems).

 

 

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roger 04 rt

Interesting project. A couple things:

 

-- If you use the ignition signal to sense engine speed remember that it may drop out on a steep downhill grade since Overrun Fuel Cutoff is accomplished by shutting off the spark.

 

-- If you run a lower gear to keep RPMs above 3000, your gas mileage will suffer.

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In some respects the BMW 2 cylinder boxer is seen as a 4 cylinder as far as sparks per revolution go. Your BMW 2 cylinder uses a "Lost Spark" ignition system so it sparks on every piston up (not every other piston up like some of the older 4 cylinder engines with conventional ignition systems).

Very interesting DR. I didn't know that. I just read up on this lost/wasted spark setup. Is this the case for all boxer engines? I read that the extra spark on the exhaust stroke is a lower energy spark, and I wonder if that will confuse the speed sensor.

 

If you use the ignition signal to sense engine speed remember that it may drop out on a steep downhill grade since Overrun Fuel Cutoff is accomplished by shutting off the spark.

I'll have to research overrun fuel cutoff, because this sounds like it may fool the cruise control mechanism into increasing throttle downhill.

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In some respects the BMW 2 cylinder boxer is seen as a 4 cylinder as far as sparks per revolution go. Your BMW 2 cylinder uses a "Lost Spark" ignition system so it sparks on every piston up (not every other piston up like some of the older 4 cylinder engines with conventional ignition systems).

Very interesting DR. I didn't know that. I just read up on this lost/wasted spark setup. Is this the case for all boxer engines? I read that the extra spark on the exhaust stroke is a lower energy spark, and I wonder if that will confuse the speed sensor.

 

Morning SnakePlisskin

 

No not all boxer engines just some (especially 2 cylinders) as the 360° firing lends itself to lost spark as it then only requires one ignition coil.

 

The later 1200 hexhead/camhead are not lost spark as they use a camshaft sensor to tell the computer when each side is on compression stroke.

 

I don't know where you are going to pick up your spark signal but if off the secondary side just remember that on the 1100/1150 BMW boxer one side sparks (positive polarity) & the other side sparks (negative polarity).

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-- If you use the ignition signal to sense engine speed remember that it may drop out on a steep downhill grade since Overrun Fuel Cutoff is accomplished by shutting off the spark.

 

Morning Roger

 

Are you sure on this?-- I haven't ever actually checked it but I can't say I have seen my timing light cut out on over-run (dropped throttle) fuel cut off.

 

It seems kind of strange to shut the spark off as any remaining fuel in the intake or TB area would go through into the exhaust as raw fuel.

 

I'm not doubting it just casually questioning it.

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Morning DR, I was rethinking that too. I want to go back and look at the data I have. RB

 

Morning Roger

 

See if your data shows a spark retard (not an actual shut off). I can see a spark advance change so it doesn't pop back through an open intake valve but based on automotive systems I can't see any advantage in shutting the spark off but can see an advantage of leaving it on (but maybe with an advance change).

 

 

 

 

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I don't know where you are going to pick up your spark signal but if off the secondary side just remember that on the 1100/1150 BMW boxer one side sparks (positive polarity) & the other side sparks (negative polarity).

DR, I was going to use the black wire on the ignition coil. Based on what you were saying earlier, I'm thinking this wire will generate a signal two times for each cylinder's combustion. Do you concur?

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I don't know where you are going to pick up your spark signal but if off the secondary side just remember that on the 1100/1150 BMW boxer one side sparks (positive polarity) & the other side sparks (negative polarity).

DR, I was going to use the black wire on the ignition coil. Based on what you were saying earlier, I'm thinking this wire will generate a signal two times for each cylinder's combustion. Do you concur?

 

Afternoon SnakePlisskin

 

Yes, you will get a signal on every revolution & that matches a firing on one cylinder every firing.

 

Just be careful to not put too much load on that black wire as that could damage the coil driver in the Motronic.

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roger 04 rt
Morning DR, I was rethinking that too. I want to go back and look at the data I have. RB

 

Morning Roger

 

See if your data shows a spark retard (not an actual shut off). I can see a spark advance change so it doesn't pop back through an open intake valve but based on automotive systems I can't see any advantage in shutting the spark off but can see an advantage of leaving it on (but maybe with an advance change).

 

 

 

 

Afternoon DR, I went back and looked at the data. The injection time is set to zero but the ignition angles are retarded to 4-5 degrees advance. Just before the end of overrun fuel cutoff, the stick coil dwell time is extended from about 1 mS to about 2 mS, which I guess is intended to ensure a healthy spark.

 

Having been back through the data, my original concern of a lost RPM signal was wrong. However, it may well be that a PowerCommander which relies on the INJECTION signal for RPM information loses its way since the injectors are not being pulsed. And that's what I was thinking of with the earlier post.

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I used the dip switch setting that were shown in the one link that I sent to you( the one with all the pictures). As for the issue of it loosing speed going down hill I have not had an issue with that.

Running at 3000 rpm's to make the cruise engage was only to see if I could get the unit to engage at a slower speed (25-30 mph). Yes you may ask why would you need to engage the cruise at that speed? I was just checking all ranges of the unit, if your at normal speed for freeway use there is no issue.

When using a unit such as the Rostra unit I would use the speed sensor that you can buy from Amazon, Flea Bay. You then just glue some rare earth magnets in the heads of the screws that hold the rotors onto the front wheel and when the wheel spins the magnets pass the speed sensor and create a pulse that the unit recognize as the ABS signal puts out a different wave length that the unit will not recognize. either way at the end of the day both units work well.

The Rostra unit will run you about 200 dollars and you still have to buy the control pad for another 60 dollars, while the Audio Vox unit will run you about 120 dollars and you get the control pad with it. Both hook up about the same and both work well. If I lived closer I would come over and help you hook up your unit.

Seeing how you have a 95 BMW the hook up is a lot easier than if you had a later model that have the boden box. Good luck with your hook up, If you need further help just PM me and I will try to answer your questions or keep post here and I will chime in and give you my 2 cents on the issue at hand. Good luck and remember once your done you will have that feeling that you have accomplished the task at hand and have real cruise control and not some throttle lock.

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Just be careful to not put too much load on that black wire as that could damage the coil driver in the Motronic.

DR, the installation instructions in the cruise control kit say the connection to the negative side of the ignition coil is to "monitor pulses" and that the circuit in the CC unit "receives a signal" from the ignition wire. I wonder (hope) if instead of a load drawn, there is some sort of inductive coil to measure current without disturbing it.

 

njl4, thanks for sentiment. It would be cool if you could come by. :) I mentioned the dip switch settings because I thought you indicated the unit would not engage at a low enough speed, but it sounds like have it working well. So you used the black ignition wire for the signal, correct?

 

I've installed a couple of these but the cable attachment is going to take some time and fabrication on my RS. No quick way to do it as far as I can tell. Please send/post some pics of what you did for that.

 

 

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Audiovox 250-1316 cruise control doesn't use a vacuum. It is all electrical which will probably give better results especially up hill. (Approx $175)

 

I have thought a bout a cruise control but I am still working on ideas for the sensor coming off the rear wheel. I don't like front wheel sensing if for some reason you hit a slick patch causing the speed sensed to lower in the front wheel relative to the back and the cruise requesting more power to maintain speed. That could be a disaster.

 

The other note: these after market cruise controls work on about 7,500 pulses a minute max so if you plan on the ABS sensor for pulses, that is closer to 30,000 a minute and it won't sense correctly for the speed.

 

Probably the best way to get the pulses would be to modify the Hall sensor with a third pick-up 90 degrees from the other two sensors and use that for the cruise. Then it is not interfering with signal strength for the tach or the TDC engine timing sensor.

 

Another sneaky thing I found is there are nearly 4 cable channels in the bowden box.... 2 for the throttle mixers and 1 for the handlebar input. With some gentle work with a dremel, you can complete the groove for the 4th channel and install a 4th cable to directly control the bowden box inputs with the cruise control. It is definitely buried under the battery box and mototronic unit so something I would consider at a major tear down. Rather than mess up yours, find one on Ebay and play. You can easily pick one up for under $10.

 

If you are interested in a photo of the bowden box modification, let me know and I can send you a photo of the one I modified.

 

 

 

 

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Good evening, SnakePlisskin

 

When attaching to the negitive side of your coil Be Very Careful.The wire is a wire inside of an outer layer of shielding wire. What you will have to do is very carefully cut and remove about 3/4 of an inch of the outer layer insulation, then pull the shielding wire away and apply your T tap to the inner wire. Now that you have this done you need to take care and wrap the shielding wire with high temp tape. Make sure that you don't brake the shielding wire, if so, you must solder it back together.

Make sure that NONE of that outer shielding wire makes contact with the inner wire, if so you will loose SPARK and your mind for about 2 weeks wondering what did I do? When that outer wire touches the inner wire that is what happens, no spark.

Thanks to my new friends on this form and D.R. I was able to learn a lot about that wire a couple of weeks ago. Once I got that repaired the bike came back to life.

The lesson learned here is: Be careful when you are working on that black wire.

 

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Rx_Mich, those are some good ideas. I thought about the HES, but didn't know about the Bowden box as a source. What I don't know is how the servo unit detect signals. Voltage, current, flux,...? It makes it hard to know what wire to use. I'm inclined to use the negative ignition coil wire since the CC unit was designed for that, but other signals may be possible. I would imagine that since the device is universal (to work on Yugos to Corvettes) the manufacturers would not want to risk damaging an ignition system. But who knows with the BMW motronic as DR suggested.

 

njl4, thanks for the words of caution on the ignition wire! Didn't know about the wire wrapping.

 

Boomer, the Rostra seems to have a lot more options for speed sensing. Personally, I feel like the engine or its electrical pulses should be used if possible for speed sensing to take advantage of the cruise control servo's rpm limiter circuit. (disengages the CC when the RPM spikes) I know the R1100 has its own redline rev limiter but I'd hate to have to hear it engage if say I pulled the clutch while the CC was engaged or if there was a malfunction somewhere.

 

By the way, also trying to figure out a way to add a switch to detect clutch lever pull. (This can then be used with the CC servo to disengage CC) Is there a clutch switch built into the transmission or the clutch lever itself?? Perhaps so if CC was an option on these bikes.

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Rx_Mich, those are some good ideas. I thought about the HES, but didn't know about the Bowden box as a source. What I don't know is how the servo unit detect signals. Voltage, current, flux,...? It makes it hard to know what wire to use. I'm inclined to use the negative ignition coil wire since the CC unit was designed for that, but other signals may be possible. I would imagine that since the device is universal (to work on Yugos to Corvettes) the manufacturers would not want to risk damaging an ignition system. But who knows with the BMW motronic as DR suggested.

 

njl4, thanks for the words of caution on the ignition wire! Didn't know about the wire wrapping.

 

Boomer, the Rostra seems to have a lot more options for speed sensing. Personally, I feel like the engine or its electrical pulses should be used if possible for speed sensing to take advantage of the cruise control servo's rpm limiter circuit. (disengages the CC when the RPM spikes) I know the R1100 has its own redline rev limiter but I'd hate to have to hear it engage if say I pulled the clutch while the CC was engaged or if there was a malfunction somewhere.

 

By the way, also trying to figure out a way to add a switch to detect clutch lever pull. (This can then be used with the CC servo to disengage CC) Is there a clutch switch built into the transmission or the clutch lever itself?? Perhaps so if CC was an option on these bikes.

 

 

Morning SnakePlisskin

 

Unless your 95 has been converted it probably doesn't have a Bowden box (Bowden box was added to later BMW boxer bikes).

 

Your bike should have a switch on the clutch lever assembly (so your engine will start while in gear with clutch lever pulled in). On older bikes sometimes that switch has been by-passed.

 

You might be able to use the existing switch & a diode, or relay, or maybe cobble in a clutch switch from the BMW 1200Rt as those have dual outputs (one for starting & one for cruise disengagement)

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Thanks Boomer. I didn't know they made that. The next step is to see if it dilute the ABS signal in any way that would interfere with it's operation.

 

I am a big fan of getting the speed input from either the engine itself or the rear wheel. Speedometer or front wheel I just don't feel comfortable with in anything the clean road and dry weather.

 

My first thought was to use the front wheel and insert a small neodymium magnets in the hex key slot for the rotor bolts with a pickup sensor. As far as I know the HES sensor has a power wire,ground, and sensing voltage wire. A transistor is tripped when a magnet buried in the crankshaft to change the voltage. Those type of sensors have to be voltage spikes either positive or negative depending on the polarity of the magnet. A reference voltage of 5v and in the field of the magnet will jump +2.5V to 7.5v or drop to 2.5 volts.

 

The ABS sensor is a bit different... it has the magnet inside of it and the tooth of the rotor in close proximity changes the magnetic field to create a voltage drop or increase. A transitor detects the change in magnetic field and report a voltage change.

 

A side note...if your ABS shows a fault both lights flashing simultaneously one of the first things to check is if you have a small metal shaving from road debris stuck to the sensor magnet. Wipe both wheel sensors clean with a rag and it should work again.

 

If your ABS fault lights are on in alternating fashion (as mine did when a connector came loose), then the bike computer needs to have a hard reset. It will not correct itself even after the problem has been rectified. A chassis grounding wire to the center computer plug module under the seat, turning the bike on and press the ABS button and hold for 5 seconds will reset it. :)

 

 

 

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Rx the only thing I have found these cruise controls sensitive to is the brake switch. Your concern about the system getting a possible false signal from a front wheel and then adding power in an uncontrolled way isn't the way I have found these cruise control units work.

As far as an over rev situation and putting in a clutch switch I haven't found that necessary. A quick tap on the brakes has worked for me and I have even played with doing power shifts with the cruise on to no ill effect. Again these units don't react super fast and if they did it would be a pretty jerky ride. BTW that doesn't mean I put the unit switches into high sensitivity.

 

As to affecting the ABS signal by putting in a divider, based on the reports from people who have done it there isn't any issues.

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Good evening,

 

I have installed an Audio Vox cc100 unit on my bike, The hook up was pretty straight forward. On my unit this is how the unit detects RPM surge.

Ignition coil monitor. This monitors the frequency of the ignition coil to set and maintain your cruising speed. DO NOT CUT THIS WIRE. It has an in-line noise filter. You'll notice the big red warning label to remind you not to cut/shorten the wire. I tapped this into the negative side of the ignition coil. It is a black wire coming out of the bottom of the coil. (The brain in the servo unit also uses this connection to detect RPM surges. This is a safety feature. If you pull in the clutch without hitting the brakes, the cruise control will sense the sudden RPM increase and disengage. When I tested this feature, I pulled the clutch in while cruising at around 4000 rpm. The cruise control disengaged before the RPMs hit 4500.)

This is why I used the negative side of the coil wire. Just be careful with this wire.

 

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Unless your 95 has been converted it probably doesn't have a Bowden box (Bowden box was added to later BMW boxer bikes).
I've heard of the Bowden boxes but have not read up on them yet. Is the purpose of the Bowden Box to split the throttle cable? If so, then no, I don't. I have a single throttle cable to the left side and a crossover cable to the right.

 

Your bike should have a switch on the clutch lever assembly (so your engine will start while in gear with clutch lever pulled in). On older bikes sometimes that switch has been by-passed.
Thanks for the tip. You are correct, I held down the start button and slowly pulled in the clutch until the starter engaged. I then identified the wire and now have a way to tap into it. Thanks! Before that, I tried to listen for a microswitch clicking sound, but it was silent.

 

Assuming I can find a safe and reliable way to detect speed, my next main concern is will I have enough vacuum to operate the servo? I've installed this exact same unit on a older 4 cylinder Mazda and found the vacuum a little lacking. It worked, but sometimes it was slow to respond. Also, during uphill climbs, the servo by itself could not fully depress the gas pedal. I installed the kit 20 years ago but distinctly remember calling technical support and complaining, and the tech suggested a vacuum booster. I then installed a 4" diameter ball-shaped booster and this improved the responsiveness as well as enabling the servo to fully depress the gas pedal. Note that in this installation, I was drawing vacuum directly from a previously capped (spare) vacuum port coming off the intake manifold.

 

A key difference here is that the hp/weight ratio on the bike is much higher, so a sluggish/weak servo might still be functional. In fact, the reduced vacuum might even make the operation smoother and more desirable. One way to find out!

 

 

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Good afternoon,

 

Your bike is a 95 correct? if so you will not have a boden box. What you will have is, your throttle cable from handle bars will run down to the Left hand side throttle body. Your choke cable will also run to the left side throttle body, There is a 3rd cable attach to the left side throttle body will be a cross over cable and this will connect to the right hand throttle body.

The Boden box didn't come until later years, D.R. would be able to give you an exact year.Being how you have a 95 you will have the set up described above.

 

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Originally Posted By: njl4

 

The Boden box didn't come until later years, Being how you have a 95 you will have the set up described above.

 

 

 

Afternoon njl4

 

That is usually the case but keep in mind that over the years a number of those early bikes were converted to a Bowden box system in an attempt to eliminate surging so you have to ask (IF) the bike has a Bowden box or not, or ask if it has been converted.

_________________________

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Thank you, D.R.

This is the kind of information that this forum is know for. It enlightens all of us when we learn and read these post. Again Thank you.

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