Lambretta Choke Cable
The choke cable on a Series I through III Lambretta runs from the choke lever on the right side of the glovebox, to the carburetor on the right side of the engine. The cable has two small soldered nipples on each end and must be a specific length to work properly. When the small choke lever is turned on the frame it simply pulls the cable by about a quarter inch which allows the starter jet to be activated and provide a richer mixture for starting.
To make things easier it is a good idea to remove the air filter so you can get access to the point where the choke cable connects to the carb. There is more info on how to do this on the Lambretta air filter page.
Once the air filter, or at least, the air filter tube is out of the way you can start be removing the choke plunger from the carb body. Using a pair of pliers or a small metric wrench, unscrew the plunger assembly from the carb body by turning it anti-clockwise.
At this point you should be able to bend the cable where the spring goes into the carb, and pull out the spring and the small brass plunger. If your cable has actually snapped it may be tougher to remove the plunger. You may need to remove the carb to shake it out while holding the carb upside down.
Remove the brass plunger (red arrow) from the end of the cable pushing the small end nipple out of the hole just under the spring. Once this is removed the spring, adjuster (blue arrow) and 90 degree bend tube (green arrow) will all be able to be removed. This will release the slack on the cable and allow you to release the other end from the choke lever on the right side of the frame.
Follow the cable back to the right side of the bike and you will see where it connects to the inside of the choke lever just under the toolbox. There is a metal retaining cap (red arrow) that needs to be pulled clear of the lever assembly in order to allow the cable to be removed from the lever.
Once the metal cap is clear the cable can slide out of the choke knob in the same manner as the brass plunger on the carb end. Now that both ends are free you can replace the old cable with a new one. As you remove the old cable, note where it passes through the frame so that the new one can follow the same route. Make sure to lubricate the new cable before installing it. Thread the new cable through the metal cap, and attach it to the choke lever assembly by pushing the nipple into the slot.
On the carb end, thread the 90 degree bend, followed by the adjuster, and finally the spring. You'll need to compress the spring with your fingernails so you can attach the brass plunger.
Try a test before you attach the plunger back into the carb body. Turn the choke lever from on to off and you should get results like above. The left image is off and the right is in the on position. The adjuster will allow you to fine tune the travel if the length of the cable is not just right. If everything looks good, then reattach the plunger to the carb, refit the air filter and you are done.
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