Repair the carburetor if any of its parts break or if the carburetor performs unsatisfactorily after adjustment in all engine operating modes
Before disassembling, wash the carburetor with kerosene to remove dust and dirt.
When using leaded gasoline, pre-soak the carburetor in kerosene for 10–20 minutes.
Procedure for disassembling and assembling the K-131 carburetor
Unscrew the five screws securing the float chamber cover.
Carefully lift the cover so as not to damage the float mechanism, disconnect the low-speed rod, remove the cover and float chamber gasket.
Turn the lid over and, holding the float, remove the float axis from the stands.
Remove the float and carefully remove its needle with the sealing polyurethane washer from the fuel supply valve body.
Unscrew the valve body and remove its gasket.
Unscrew the filter plug, remove its gasket and remove the filter mesh.
Unscrew the accelerator pump nozzle and remove the sealing washer.
Disassemble the air damper drive mechanism and remove the damper only if the operation of the mechanism is unsatisfactory, and also if the gaps between the wall of the air pipe and the damper when closing it exceed 0.2 mm.
Separate the mixing chamber from the float chamber body by unscrewing the two bolts and, unscrewing the accelerator pump drive shackle, remove it from the rod and lever.
After removing the mixing chamber gasket, remove the large diffuser from the float chamber housing.
Remove the accelerator pump piston assembly with its drive parts and the economizer drive rod.
Unscrew the economizer valve assembly and remove it from the well.
Unscrew the plug of the emulsion tube well together with the gasket and remove this tube, unscrew the idle air jet.
Unscrew the plugs of the channels of the fuel and air jets of the main metering system and the idle fuel jet, remove the gaskets of these plugs and unscrew the corresponding jets.
Remove the accelerator pump valve lock and remove the valve from the well.
Remove the retaining ring and ball of the accelerator pump check valve. Do not press out the small diffuser unless necessary.
When disassembling the mixing chamber, unscrew the idle mixture quality adjustment screw and remove its spring.
Remove the throttle valve and its axis only if:
- – the throttle axis does not rotate freely in the chamber bosses;
- – gaps between the walls of the chamber and the damper in the closed position are more than 0.06 mm;
- – the upper edge of the throttle valve in the closed position does not coincide with the axis of the transition hole F 1.6+0.06 mm (deviation ±0.15 mm is allowed).
After disassembling, wash all carburetor parts in unleaded gasoline or hot water at a temperature of at least 80°C, then blow with compressed air.
All carburetor parts must be clean and free of soot and tar deposits. Jets and other metering elements must have a given capacity or dimensions.
The economizer valve assembly must be sealed.
When checking its tightness under a pressure of 1200 mm water. Art. No more than four drops of water per minute are allowed to flow.
The degree of wear of the accelerator pump piston and the walls of its well, as well as the tightness of the check valve, must be such as to ensure a pump flow of at least 8 cm 3 for 10 working strokes of the piston.
Check the float for leaks by immersing it in water with a temperature of at least 80°C.
The release of bubbles from the float indicates a violation of its tightness.
Solder the damaged areas of the float with soft solder, after removing any fuel that has gotten into the float. After soldering, check the weight of the float, which should be equal to (13.3±0.7) g.
Adjust the weight by removing excess solder without disturbing the seal of the float.
The surface of the housing connector and the float chamber cover must be flat, the permissible deviation from the plane is no more than 0.2 mm.
Assemble the carburetor in the reverse order of disassembly, taking into account the following:
- 1. If the throttle or air damper was removed during disassembly, tighten the screws securing them during reassembly.
- 2. Check that the economizer is fully engaged and, if necessary, adjust as indicated in the article “Maintenance of the K-131 carburetor.”
- 3. Adjust the fuel level in the float chamber. On the assembled carburetor, check the relationship between the air and throttle valves.
With the air damper completely closed, the throttle valve should open slightly at an angle of 17–21°, which corresponds to the gap between the wall of the mixing chamber and the edge of the damper (2.5 ± 0.2) mm.
If the specified requirement is not met, bend the small rod crankshaft rotation speed.