Earlier, when I first got the bike, I rebuilt the carburetors and removed the “Pulse Air” system from the air box. You can read about how I did that here.
- 13 BMW 1983 R100RS Rebuild Bing 94/40 Carburetors & Karcoma Petcocks
- 13 BMW 1983 R100RS Update Pulse Air System and Replace Oil Breather Hose
The following includes similar information to what’s in the documents above, but here I’ve simplified it to just removing these components.
The carburetors are easy to remove. They are attached to the air box air intake and the engine cylinder intake spigot with straps.
The air intake rubber bushing attaches to an aluminum bushing in the air box. I push the rubber bushing down the air tube to get it off the air box bushing. Then I remove the air intake from the carburetor.
There is a steel bushing inside the air box end of the air intake.
I make the air intakes to make it easier to get the right one on the correct carburetor.
Here are the air intake parts.
I pull the carburetor off the engine intake bushing and then remove the bushing from the intake spigot. I also remove the fuel lines from the metal tee.
Remove Choke & Throttle Cables From Carburetor
The Bing carburetor on the 1983 RS uses a return spring for the choke since the choke lever is attached to the handlebar and uses a flexible braided steel cable. The earlier style choke used solid wire with a lever on the left half of the clam shell cover of the air cleaner.
I remove the return spring so I can easily rotate the choke lever to remove the cable ferrule from the slot in the arm. Then I reattach the return spring.
Then I loosen the lock nut and unscrew the choke cable adjuster from the top of the carburetor.
The procedure is similar to remove the throttle cable.
Choke & Throttle Bowden Cable Details
Both the choke and throttle cables on the 1983 model use a Bowden system. There is a single cable that goes to the handlebar that connects to end of a cable splitter mechanism. The other end has the two cables that go to either each choke lever or throttle plate lever on the carburetors. These cables look the same, but the part numbers are printed on the sheath. I put a label on each so I won’t get them confused when it’s time to put things back together. You can see the internals of the Bowden cable splitter here:
Since I am converting this bike to an RT model, I will have to replace the upper handlebar cables for the throttle and choke since they are longer on the RT model, than the RS model due to the wider RT handlebar.
Here is the carburetor stripped of the fuel line and cables.
Remove Air Box
The yellow pipe inside the bushing in the air box is part of the engine crankcase vent system. I remove the bushing.
Then I remove the cover with the intake snorkels from the air box and the metal cover clamps.
Remove Intake Tunnels and Crankcase Breather Hoses
Inside the air box are the intake tunnels and the hoses for the engine crankcase breather that feeds crankcase vapor into each carburetor. On the earlier models with the clam shell air filter housing with the cylindrical air filter, there was one breather hose that fed into only the right carburetor air intake tube.
Earlier, I removed the solenoids and the piping to the exhaust passages in the cylinders that is part of what BMW called the “Pulse Air System”. You can read about how I did that here.
The crankcase breather hose comes into a tee fitting inside the air box with a clip to secure it. I slide the clips down the breather hose to remove the hose from the tee and then remove the intake tunnels by pushing them back into the air box.
Inside the intake tunnel is a plastic vent pipe that delivers the crankcase vapor into the carburetor intake tube.
The rubber breather hose presses into the intake tunnel. If you remove the hose, you can pull the plastic vent pipe off the breather hose.
I mark the intake tunnels so I will easily know which side they go to.
Then I remove the breather hose tee. It fits into the breather hose inside the top engine cover that goes to the crankcase breather valve assembly.
The air box is secured to the top of the transmission with two bolts and one nut. The left bolt and right nut secure the transmission to the engine. The middle bolt used to secure the bottom strap for the older style clam shell halves. I remove the bolts and the nut.
The breather hose from the crankcase breather valve has a grommet that the tee fit into. I push the grommet out of the box, slide the air box to the rear and lift it off the top of the transmission.