- Remove the spark plug from the cylinder head, reattach it to the suppressor cap of the HT lead, then hold the metal part of the plug against earth (your engine mount). With the ignition switch in the ON position (fuel and choke OFF) give the kickstart lever a brisk kick. You should see a blue spark jump the plug gap.
- Still No Spark. Remove the suppressor cap from the HT lead (should screw off) now repeat the above procedure holding the lead 5mm from an earth (the engine mount). You may need to cut 10mm of HT lead off, if the copper core is corroded or damaged.
If you now have a spark, either the spark plug or the suppressor cap is broken and will require replacement.
- Still No Spark. Trace the HT lead back to the CDI unit, checking for damage. The CDI Unit should have four wires plugged in to it (Yellow, White and two Greens). Three of these come from the Stator plate (behind the flywheel). One of the greens comes from the loom, not the stator plate. Unplug the green that comes from the loom and repeat the procedure as per instruction 2.
If you now have a spark, there is a problem with either the loom, the ignition switch, or the head lamp connection block, these will need to be checked and replaced as required.
- Still No Spark. The CDI unit has a yellow wire coming out of it (cast in to it). This wire should be attached to earth. Check that it has a good connection to earth. Also run an additional wire between the engine and the frame, to ensure a good earth connection. Now repeat the procedure as per instruction 2.
If you now have a spark, poor / intermittent earth connections are by far the most common fault with the electronics of the Lambretta, corrosion is often the cause.
You will now require a multi-meter to carry out further tests.
- 5. Still No Spark. Disconnect the three wires connected to the CDI from the stator plate (Red, White, Green). Connect the multi-meter terminals, one to the Green wire and one to the White wire. You should measure a resistance of between 400 and 500 Ohms. A figure of higher or infinite resistance suggests a break in either wire or a damaged low-tension coil. A lower Figure suggests either a trapped wire or a damaged low-tension coil.
If you now have to remove the kit, checking carefully whilst removing that there is no visible damage from abrasion, heat or trapped wires to identify the problem.
6. Still No Spark. You should now seek the help of your local dealer or ourselves as the stator plate and CDI unit will require testing with workshop equipment to identify the fault. If all other tests have been carried out correctly either the CDI unit (extremely rare) or the pickup box will be the cause of the fault.
Note, Please carry out these checks methodically, and carefully, it wastes both your time and ours when a perfectly good component is sent back.
When sending any component back to us. It must be well packed (must arrive in fit condition) with a letter describing the fault encountered (even if it has been discussed over the phone). You must include your name, telephone number and return address.