Aprilia RS 50 Tech Tips

Aprilia RS 50 Tech Tips Part 2:

Removing the Airbox, Carburetor, Manifold, and Reed cage

Removing the airbox:

Now that the tank is off the next step is to remove the stock airbox and carburetor. First locate the clamp that holds the airbox to the carburetor itself. Using a flat blade screwdriver (a long one) loosen this clamp a few turns (see picture 1). Now locate the bolt at the rear top of the airbox. This M6 bolt has an 8mm hex head. Remove this bolt and that is all of the fasteners that hold the airbox to the carburetor and to the chassis. Firmly grab the airbox and pull straight up on it. This should allow it to separate from the rest of the assembly.

Removing the carburetor:

The first step in removing the carburetor itself is to remove the two bolts that hold the slide in place with a flat blade screwdriver (see picture 2). This is the point where the throttle cable goes into the carburetor. Once the two screws are removed, the slide assembly will come straight up and out of the stock carburetor. You can now remove the cable from the slide assembly. Next, loosen the clamp bolt that holds the carburetor onto the manifold. Once this is loose, the carburetor and all associated vent lines can be pulled out of the chassis. Next, remove the fuel line from the stock carburetor. This will be used on your aftermarket carburetor, or you can get a new fuel line that incorporates a filter.

Removing the throttle cable:

Now is the time to remove the throttle cable from the splitter junction. This is a simple process, but many people get confused at this point. First remove the two M4 Allen bolts that hold the oil injection pump cover onto the motor (see picture 3).

Now you will see where the second cable from the splitter junction terminates. This is the oil injection pump cable. It moves with the throttle cable to allow more oil into the case when the throttle is opened. Carefully rotate the arm that the cable terminates in to the rear of its travel (see picture 4).

You will now be able to remove the cable end from the arm. The junction splitter is made in two halves so you can remove the cables from it. The top cap is pressed on pretty well so some force will be required to break it loose. Once loose, you simply push both cables and the piston upwards. They ride in a small groove inside the junction. Remove the throttle cable from the junction splitter. If you are going to premix from now on, leave the oil pump cable disconnected. If you are going to continue to run the oil injection system, then take note of how the cables were routed and how the ends fit in their respective places. When reinstalling the cables, hook up the oil pump cable only after you are finished reinstalling cables inside the splitter junction.

Removing the manifold:
Removing the manifold is accomplished by removing the four M6 Allen bolts with a 5mm Allen driver and taking off the two small hoses that serve to heat the stock manifold (see picture 5). These hose clamps can be easily removed with a set of wire dyke pliers, and then the hoses must be pulled free. Take note at this point that two of these bolts hold stuff in addition to the manifold. The one in the top left of the manifold also holds three grounding wires that must be reconnected in order for your bike to run. The one in the bottom right holds the clutch cable in place. Take a careful look to see how these are installed. These both will need to be reinstalled on your new manifold. Once the four bolts are removed, the manifold should be free to come off. Sometimes the gasket will cause it to stick and some tapping with a rubber mallet may be needed.

Removing the reed cage:
At this point, you may either be replacing the entire reed cage, the reeds themselves or just removing the restrictor. You should see the backside of the reed cage at this point. It has a small opening that matches with the exit of the manifold. To remove the cage, try first to simply pull it out of the case with finger pressure. If that fails, resort to careful tapping and prying. This small opening is the reed cage restrictor (see highlighted picture 6).

It will only restrict your motor, if you are running a carburetor larger than the stock 12mm. For a stock carburetor, the restrictor is not a bad thing, since it smoothes the transition of air into the reed cage. For all the big carburetor users, it must come out.

The easiest way to remove the restrictor is to first remove the reeds and reed stoppers (be careful), and attack the restrictor from the front side (see picture 7). Hold the cage firmly and use a sharp Phillips screwdriver bit to remove the four screws that hold the reeds down. Once these screws are out, carefully pull the reeds away from the cage, and lay them down on a clean surface in the same way they were positioned in the cage. This is important, as reeds are usually curved to a very small extent to aid in their sealing. They need to be fitted in the same way they were originally fitted. With the reeds removed, take a screwdriver of the appropriate size and push on the restrictor from the back side. It will require some force to make it come out. Be careful not to let the tool push against anything but the restrictor (see picture 7).


You do not want to damage the sealing surfaces of the reed cage. Carefully reinstall the stock or carbon reeds and the reed stoppers

Source: Aprilia Forum