This tutorial is also available in French ➔

HS4 waxstat carburetor maintenance on Austin Mini

Vehicle ➔ Mini 1000 am1991 automatic gearbox

Difficulty ➔ Easy

Time ➔ 3 hours

Summary

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The HS4 carburetor maintenance kit (CSK65 kit) does not include the throttle and its shaft. Before ordering, check the throttle shaft on the carburetor. If it has play, order the HS4 carburetor restoration kit (CRK121 kit).

Required Tools

Remove the air filter housing (➔ see the tutorial ''Replacing the HS4 air filter'' Steps 01 to 02).

Op 02

Remove the carburetor (➔ see the tutorial ''Disassembling the HS4 carburetor'' Steps 02 to 12).

Op 03

Unscrew and remove the piston damper. Unscrew by hand.

Op 04

Unscrew the 3 screws of the suction chamber. Use the flathead screwdriver.
Remove the chamber. Pull by hand.

Remove the suction chamber straight without tilting it. This could damage the piston or the needle.

Op 05

Remove the spring.
Carefully remove the piston + needle assembly. Pull by hand.
Empty the oil contained in the piston rod.

Warning! The piston + needle assembly is very fragile.

Op 06

Release the starter lever return spring. Use a screwdriver to disengage it from its support.

Op 07

Remove the retaining clip of the starter/jet linkage rod. Use a flathead screwdriver.

Op 08

Unscrew the nut securing the flexible tube of the jet to the bowl. Use the 7/16'' spanner.

Sometimes, the seal and the small washer remain stuck in the tapping of the bowl. Do not forget to remove them.

Op 09

Remove the jet from its housing. Pull by hand.

Op 10

Remove the jet adjustment nut and its spring. Unscrew by hand.

Op 11

Remove the 3 screws securing the bowl cover. Use a flathead screwdriver.

Recover the carburetor number plate.

Op 12

Remove the bowl cover + float assembly. Pull by hand.

Op 13

Remove the gasket and perfectly clean the support surface of the cover. Use a cutter.

Op 14

Remove the float pin. Use the pliers.

Remove the pin from the knurled side. It will be easier.

Op 15

Remove the needle.
Unscrew and remove the seat. Use a 9 mm socket.

Op 16

Unscrew the bowl fixing screw. Use the 11 mm socket spanner.

Op 17

Remove the bowl and its spacer. Pull by hand.

Op 18

Unscrew the 2 screws securing the air filter elbow. Use the Phillips screwdriver.

Unscrew screws securing air filter elbow

Op 19

Remove the air filter elbow and its gasket. Pull by hand.

Reassemble the carburetor

Op 20

Thoroughly clean all the carburetor components. Use gasoline, a brush and a cloth.

Op 21

Fit the air filter elbow and its gasket (CSK65 kit) on the carburetor body.
Tighten the 2 fixing screws with their washers (GFK1125). Use the Phillips screwdriver.

Op 22

Fit the bowl and its spacer on the carburetor body.
Tighten the bowl fixing screw with its spring washer (GFK1124) and its flat washer (GFK1113). Use the 11 mm socket spanner.

Op 23

Tighten the needle seat (CSK65 kit). Use a 9 mm socket.
Fit the needle (CSK65 kit). Simply engage it by hand.

Op 24

Fit the float and engage its pin. Use the pliers.

Engage the non-knurled side of the pin first. The knurls lock the pin on its support.

To make sure the system is working, blow into the fuel inlet tube and operate the float to check that the inlet is blocked when the float is raised.

Op 25

Fit the cover + float assembly and its gasket (CSK65 kit) on the bowl.
Tighten the 3 screws with their washers. Use the flathead screwdriver.

Do not forget to position the carburetor number plate on one of the bowl cover fixing screws.

On my carburetor, I had a flat washer on the screw holding the number plate and spring washers on the other 2 screws. I do not know if it was like that originally or if it had been modified.

Op 26

Tighten the jet adjustment nut and its spring. Screw in by hand.

Tighten the nut until the spring is completely compressed. Do not force it. We will adjust the carburetion later.

Op 27

Fit the jet in its housing. Insert it by hand.

Op 28

Check that there is a washer and a seal at the end of the flexible jet tube.
Fit the seal 5 mm from the end of the tube. Use the ruler.

Op 29

Fit the flexible jet tube on the bowl. Push by hand.
Tighten the nut. Use the 7/16'' combination spanner.

Op 30

Fit the starter/jet linkage rod on the jet.
Fit the retaining clip. Push with your finger.

The rod must be positioned below the jet lug (when the carburetor is in a vertical position).

The retaining clip has a mounting direction:
• One end is bowl-shaped to accommodate the ball of the rod.
• One end has a lug to lock onto the jet lug.

Op 31

Retension the starter lever return spring. Position it on its support.

Shape a mini hook with a wire and use it to pull on the spring and put it in place.

Op 32

Make sure the entire starter lever and jet system works well.

The jet should slide freely and return to the stop when the starter control is released.

Op 33

Reassemble the piston + needle assembly.
Fit the piston spring.

Check that the piston + needle assembly slides freely.

Op 34

Reassemble the suction chamber and its 3 screws. Use the flathead screwdriver.

Op 35

Reassemble the piston damper. Screw in by hand.

The oil will be put in the piston when the carburetor is on the vehicle.

Op 36

Check that the piston slides freely.

When the carburetor is reassembled, the piston is still accessible by hand through the air filter elbow.

Op 37

Preset the jet adjustment nut. Unscrew the nut by 2 turns.

A tip for counting the 2 turns: just count 12 flats when unscrewing the nut.

Op 38

Admire this magnificent carburetor. It's like new. Well done! Excellent work.

Op 39

Reassemble the carburetor (➔ see the tutorial ''Disassembling the HS4 carburetor'' Steps 13 to 29).

Op 40

Adjust the carburetor mixture (➔ see the tutorial ''Adjusting the HS4 carburetor mixture'').

Op 41

Reassemble the air filter housing (➔ see the tutorial ''Replacing the HS4 air filter'' Steps 10 to 13).

The End