When I did the inspection of the bike, the throttle and choke cables looked pretty worn with kinks showing in the outer armor. The Bowden connector rubber boots are disintegrating. I’m replacing the cables before riding the bike as I don’t want a stuck throttle or broken cable to happen.
I ordered the following from MAX BMW.
|32 73 1 242 593||CHOKE CABLE – L=671MM (from 09/80), To Handlebar||1|
|32 73 1 242 139||CHOKE CABLE – L=531MM (from 09/80), To Carburetors||2|
|32 73 1 242 128||ACCELERATOR BOWDEN CABLE-L=675MM (from 09/80), To Handlebar||1|
|32 73 1 242 135||ACCELERATOR BOWDEN CABLE-L=517,5MM (from 09/80), To Carburetors||2|
|32 73 2 301 342||Choke/Throttle Bowden PROTECTION CAP||2|
Removing Choke Cables
The 1983 R100RS has a handlebar operated choke instead of the one mounted to the left side air box cover.
A single cable from the handle bar lever pulls a plug inside the Bowden connector to which is connected the two cables that go to the carburetor choke levers.
To start, I remove the plastic cover on top of the choke lever using a utility knife to pry the cover up.
Under the cover is a large bolt that attaches the choke lever to the handlebar housing.
Unscrewing the large bolt reveals a special washer and the nipple of the choke cable connected to the cam on the choke lever. One of the cable stands is broken so it certainly is time to replace the cables.
I use needle nose pliers to pull the nipple out of the cam.
The cable routes through a slot in the housing.
Once the handlebar cable is removed from the choke lever, I work on disassembling the Bowden connector. It is on the left side of the frame next to the starter relay with the shredded rubber boot.
To open it, I unscrew the end cap that has the two cables going to the carburetor choke levers.
Then I screw in the adjuster for the handlebar cable all the way into the Bowden connector so the rubber plug extends outside the Bowden connector.
I pull out the plug that connects all three cables together. The handlebar cable is in the middle and the carburetor cables are on the sides of the rubber plug.
I remove the choke cable adjuster from each carburetor so I have slack in the cables.
I push the carburetor cables out of the plug and pull them through the slots in the rubber plug and through the two holes in the threaded top.
These are the Bowden connector parts. The cable cap and rubber plug are on top while the body of the Bowden connector and the rubber boot that fits over the handlebar cable are on the bottom.
Install New Choke Cables
Shown in the picture below are the new choke cables and Bowden connector rubber boot. The long cable (part# 32 73 1 242 593) is the handlebar cable and the two shorter ones, which have the same part number (part# 32 73 1 242 139), go to the carburetors.
I install the new rubber boot on the handlebar cable. I remove the nut on the cable adjuster, spray a little silicone lubricant inside the boot and the slide it over the adjuster. I find twisting it on the threads helps pull it along the adjuster without tearing the small hole. Go slow and it will slide over the adjuster without tearing.
Next, I thread the cable adjuster all the way into the Bowden connector so I have maximum inner cable length available so I can insert it into the middle of the rubber plug.
Then I insert the carburetor cables into the slots on the side of the plug.
I use a little Dry Slide on the cables near the ends where they seat in the rubber block. I screw the cap onto the Bowden connector. The Dry Slide evaporates leaving graphite stuck to the steel strands of the cable.
I insert the ferrule into the choke lever cam and grease the cam.
Then I route the cable into the choke housing that I also greased.
I attach the choke handle to the housing using the cover screw. Then I back out the handlebar cable adjuster at the Bowden connector until there is just a little slack in the handlebar cable. When the choke cable slack is adjusted, I push the rubber boot over the adjuster.
I insert the carburetor choke cable adjusters into the carburetor and adjusted the cables at the carburetor so both chokes open at the same time. I make sure the carburetor choke levers are all the way to the stops when the choke is turned off at the lever.
Replacing Throttle Cables
The procedure is the same as for the choke cables except the handlebar throttle assembly is different. I remove the cover screw to expose the cam and chain inside the throttle housing. They are completely dry, but should have some grease to lubricate the cable assembly and prevent rust.
The throttle Bowden connector is on the right side of the frame tube under the voltage regulator.
I install the cable ferrule of the new cable in the end of the chain and attach the cover to the throttle assembly. When I get the handlebar cable installed into the Bowden connector, I use the handlebar cable adjuster to remove most of the slack in the handlebar cable. Then, I install the carburetor cable adjusters in the carburetors and adjust them so the throttle levers move at the same time and there is a little bit of slack.
All done and now I don’t have to worry about broken or stuck cables.
2019-11-27 Edits and typos.
I was wondering how to deal with the throttle cables when there’s a brake fluid reservoir?
I don’t understand what you are asking.
In summary, the single throttle cable from the right-hand throttle assembly goes to the Bowden connector and each of the cables to the carburetors are attached to the other end of the Bowden connector. Access to the right hand throttle assembly requires removing the single screw in the cover. It is not obstructed by the front brake master cylinder.
I’m having trouble getting the cables to snug up to where the throttle handle will successfully open and close. I am in Casper Wyoming. 83 R80RT. Carbs rebuilt. Velorex detached in case I
have to transport it to a place that can help. If near Casper, feel free to visit.
Brook, I am having difficulty routing the throttle cables on my 78 RS that I have been rehabing – I continue to end up about 1/3 inch too short, which doesn’t allow the throttle to close. Do you have any photos or descriptions of the best way to route the cables? Your suggestions are always helpful too.
The cables route via the spine tube and fit in one of the holes in the large rubber grommet (part# 16 11 1 230 030 SUPPORT RUBBER) that several holes in each side of it for cable routing. The correct cable and length is:
32 73 1 236 616 ACCELERATOR BOWDEN CABLE – L=1108MM
Measure your inner cable length to see if it’s the correct length. The 1108 mm is from the end of the nipple that fits in the slot of the throttle cam inside the right side throttle housing to the top of the adjuster that is on the other end of the cable. Push the adjuster shaft all the way to the other end of the inner cable. Make the measurement to the top of the adjuster that the outer sheath of the throttle cable fits into.
If you don’t have the stock handlebars on the bike that makes a difference.
I hope that helps.
Thanks for you prompt and helpful guidance! I was able to confirm that I have the correct cables, but the grommet is not on the bike. More importantly, I was able to determine my error quickly with your input.
Let me know if you are ever in the Seattle area. I would like repay the favor(s) with a meal a couple of the PNW’s famous craft brews.
I’m glad my general comments were helpful in showing the “error of your ways”, so to speak. Been there, done that. 🙂
Thank you for the kindness. If this virus gets into the corral and they can keep the gate closed, I will be doing some riding around again and will keep your offer in mind.