Lambretta LD LC No Spark Tips & Tricks
If your reading this news post and find that you still have problems and have rectified it by other means, I would be greatful if you could get in contact, so that I might update this page to aid others with problems in this area.
If your Lambretta is in working order consider removing typical items and placing them to one side and purchasing a new set. Starting problems can occur frequently, depending on how frequently you ride your Lambretta and it’s storage conditions. Then should you have any problems in the future, you have a working set that you are confident has no problems. These items may include:
Points (& cables / small leads if they come off!) , Condensor (AKA resistor), spark plug and complete HT Lead (Note of importance, the spark plug and cap should be the non resistant type – read further information below) and coil if you can.
It is important to note that Multi Reader Volt / Amp / Ohms Tests should not be relied upon in regards to readings you obtain from it as they are often wrong. I will endeavour to cover some of my own tests complete last year in this area in regards to condensor testing, four pole coil testing and testing from the green cable.
To aid you further in your understanding, the comments below should also be read in conjunction to the downloadable services mans book (pages 69 to 77)
The Lambretta Serviceman’s Book by D B Palmer: 1st edition TV Li LD LC models download
170MB (PDF – Large file) This covers Lambretta 125 & 150LI / 175 TV and Lambretta 125 7 150 LD Mk 1 2 & 3
11mb (PDF – The same file as above, but smaller – not as good a quality) This covers Lambretta 125 & 150LI / 175 TV and Lambretta 125 7 150 LD Mk 1 2 & 3
Review pages 69 to 77 for standard fault diagnostics work
- The use of a cheaper Vespa coil for a period of time, rather than a more expensive Lambrertta coil.
- Further testing on Magneto’s and Coils
- Condensor (AKA capacitor) testing in more detail (Completed in 2019, with test results to be uploaded at some stage)
“Condensor / Capacitor” Condensors (Also known as Capacitors) can sometime be problematic on Lambretta LD / LC models if it has never been changed.
The condenser is a simple capacitor that can store a small amount of current.
When the points begin to open, the current flowing through the points looks for an alternative path to ground.
A condensor is used to reduce the spark at the contact points as they open in the distributor
If the condenser were not there, the spark would try to jump across the gap of the points as they begin to open. Burning and pitting of the points can also occur with a faulty condensor.
A faulty condensor or the wiring in this area can cause either a weak or no spark. During 2019, I completed various testing in this area and when I have time, I will publish an article in this area covering this in more detail.
Summary – Always have a spare and consider replacing if you have staring problems or engine running rough issues.
“Points” Lambretta LC / LD Breaker Gap / Points & Spark Plug settings:
Ignition timing: 26 degrees BTDC
Points gap / Breaker gap: Imperial 014″- 018″
Points gap / Breaker gap: Metric 0.3 to 0.4 mm
Spark plug and electrode gap:Imperial between 0.0197″ 0.0236″
Spark plug and electrode gap: Metric 0.50mm to 0.60mm
Review of points:
- Clean your points with something like some emery paper.
- Check for pitting (Indicating condensor issues).
- Check points gap.
- Check cable connections and check they are also not loose, faulty, breaking down.
- After cleaning, insert a small piece of paper insert into points and turn the flywheel to make sure that the points grip the paper. This will prove that the points are closing.
Point to note: Most cheap Metric feeler gauges you buy online at around £3 go up to 1.00mm.
Tip: look for feelers gauges with only a few gauges, but that include 0.50mm / 0.55mm & 0.60mm, as these are the ones you will use for your Lambretta
“Bad Earth / Faulty Earth and or Damp Conditions”Damp weather can cause a leakage to earth. Check your earth cable thoroughly in this area. Check and ensure all is OK with the engine to frame earth cable.
A Lambretta never does very well in damp or wet conditions, or if they have been left standing for some time / over the winter. Consider getting a heater element of some type (hair dryer) and point it in the area of the stator plate for a short while to ensure all is dry in this area.
Remember to see the Fuel and Oils comment in this section for further information on letting your Lambretta stand fr some time
“Green Wire has spark, but still no spark at spark plug or no spark at all?” The Green wire from stator will spark if it is held close to engine. However, you may have a weak spark?
Check that you have a strong spark and not a weak one. You will of course need a dark space to check this!
If you have no spark or a weak one at that point, then you are going to need to read and pay particular attention to the comments located in this section:
- Points,
- Condensor (AKA capacitor)
- Ignition coil (4 pole system)
- Stator / 4 Pole Systems together with the associated wiring.
- Magneto (Unlikely to be this, but may need ruling out)
Quick fix: If it’s a weak spark, re-check the wire that goes from the points to the condenser. Remember that a spark from the points will take the easiest route and if your getting a weak spark, it may be arking out somewhere else inside the mag / near the flywheel. A faulty condensor can cause this. If this is the case, you may not be getting enough power to the coil (If coil installed!) or HT lead.
“Magneto – Includes general information” This post should be read in conjunction with the Stator statement below.
The flywheel has magnets embedded in it. As the flywheel turns it creates a magnetic field around coils located on the stator plate.
Search goolge for and look at the BrighSparkMagnetos.com website for information on this topic.
“what causes a magnetos magnet to lose its strength“
Summary: It is unlikely that your Magneto has lost it’s strength, that results in a weak or no spark. To date I have not been able to test this extensivly and if a magneto has lost it’s strengh. the only testing I have been able to do in thisa re is take a magneto from a working Lambretta and non starter and place the magneto on the work top and see if it will hang onto the Magneto when lifted via the screwdriver.
Additional Information In This Area
For the thinner wire coil, this aids in creating a spark for the points
For the thicker wire coil, this generates power for the lights and ignition.
These types of systems can cause a lack of power in the lighting area which in turn can effect the ignition system and cause problems with firing of the plug when the lights are on. You may therefore want to ensure that all electrical demands such as lighting remains switched off until your Lambretta has been kick started.
Note: If your using a battery operated Lambretta remember, extra care is required in maintaining the battery and if possible, consider adding a trickle charge environment to them. Some dealers will only provide a guarantee of 6 months for these types of batteries.
If you believe you have a faulty stator or magneto, you may need to borrow one from a working Lambretta to rule this out. if your in Kent and need assistance, please reach out to me.
“Bad Stator / 4 Pole System x2 Coils” This post should be read in conjunction with the Magneto statement above.
Note1: I have done much testing in regards to volt meters and trying to ascertain what a typical reading should be. In summary, do not waste your time in this area as there are currently no bench marks. I will endeavour to cover this topic in more detail at a later date. If interested, please see this external link for more information: http://www.ilambretta.co.uk/forum/viewtopic.php?f=12&t=11739
Note 2: Most of the information below applies to Lambretta LD and LC’s, which all have a four pole stator system with Green / Brown / Blue cables. It does not apply to LI’s with Pink wires!.
The coil with the thinner wire is the ignition coil, which should be see as the the green wire coming out of the mag, that connects to the coil.
The inner part of the winding is soldered to the base of the coil to ground it.
The ignition stator coil generates the power for the spark plug. It is unlikely that your stator is dying. However, if it is, it can produce a weak spark, causing the engine to miss or run poorly. You may find that symptoms are often worsened as the engine warms up.
If you believe you have a faulty stator or magneto, you may need to borrow one from a working Lambretta to rule this out. if your in Kent and need assistance, please reach out to me. “Faulty Coil (If coil used!)” I will be reviewing this area again in the future.
For coils the positive side of the coil is usually marked “II” or “15” or a + sign.
For coils the negative is marked “1” or blank or with a “-” sign.
In theory, to test from mag flange area (disconnecting from the spark plug and coil) when you kick over your Lambretta, this should produce around 1.5 to 2.0 volts AC.
In theory, you should be able to use any coil to test your Lambretta, if you believe you have a faulty one installed. However, I do not have enough information on this at present to comment any further in regards to riding with it for prolong periods of time.
Lambretta.net provides further information in this area a link to their website may be found below.
To be carried out at some stage: testing will be carried out on replacing one of my MK3 Lambretta LD coils with a cheap Vespa one. Results will be published as a News Post and link added to this page with results.
Summary: Try a known working ignition coil in place of your old one.[/vc_column_text][/vc_tta_section][vc_tta_section title=”Fake Plugs” tab_id=”1579603907818-ac22f1ed-c527″][vc_column_text]Avoid fake spark plugs and only buy from reputable places, as this may impact starting your Lambretta. Further information can be found here in regards to NGK fake plugs:
http://www.ngk-sparkplugs.jp/english/techinfo/fake/“Spark Plug – Note Avoid Resistor Made Spark Plugs & Caps” Lambretta LC / LD Breaker Gap / Points & Spark Plug settings:
- Ignition timing: 26 degrees BTDC
- Points gap / Breaker gap: Imperial 014″- 018″
- Points gap / Breaker gap: Metric 0.3 to 0.4 mm
- Spark plug and electrode gap:Imperial between 0.0197″ 0.0236″
- Spark plug and electrode gap: Metric 0.50mm to 0.60mm
- New spark plugs arrive at between 0.70mm to 0.90mm and will need to be reviewed.
Using NGK as the example, Champion are also used frequently by people.
NGK resistor spark plugs have a letter “R” near the start of the plug code, for example a BPR7HS
A non resistor (Short reach) would be B7HS or B6HS
A resistor plug is a spark plug that has a built-in resistor which is designed to suppress electrical interference caused by the spark. This is normally important for use in later motocyles and cars.
Old Lambrettas fitted with magneto type ignition do not have a powerful ignition system and the extra effort and voltage required to make a spark pass through the resistor as well as jump the spark plug gap may not occur or could be causing a weak spark, intermittent or complete loss of a spark.
For this reason a non-resistor type spark plugs (and cap) are recommended for such older vehicles.
Point to note: Most cheap Metric feeler gauges you buy online at around £3 go up to 1.00mm.
Tip: look for feelers gauges with only a few gauges, but that include 0.50mm / 0.55mm & 0.60mm, as these are the ones you will use for your Lambretta
NGK B6HS / B7HS (short reach) spark plug
- B: Indicates 14mm thread diameter in the cylinder head. This diameter is used on all LC and LD Lambrettas
- 1-9: Indicates temperature (1 Hottest – 9 coldest).
- H: Indicates 12.7mm thread reach (approx 1/2″)
- S: Standard electrode
- To my knowledge, most people use B6HS. I use B6HS, but you can use B7HS (Slightly colder plugs!)
Notes:
- When a spark plug is overheating the points burn away is increased.
- Check the plug gap frequently.
“HT Lead & Testing – Avoid Resistor Made Caps” NGK caps are mostly made from phenolic resin, a type of plastic similar to bakelite. Champion caps are made from silicone rubber.
Similar to the spark plug itself, caps can have a built-in resistor which is designed to suppress electrical interference caused by the spark. This is normally important for use in later motocyles and cars.
Old Lambrettas fitted with magneto type ignition do not have a powerful ignition system and the extra effort and voltage required to make a spark pass through the HT lead may not occur or could be causing a weak spark, intermittent or complete loss of a spark.
For this reason a non-resistor type spark caps are recommended for such older vehicles.
HT leads can have:
- Vibration damage
- Heat damage
- Abrasion damage
- Ends can become loose
Summary info
Make sure both ends of your high tension lead are screwed right in and making a good connection.
One way to test a lead would be to hold a meter probe on each end of the cable and read the total resistance on the meter. The maximum resistance should be around 12,000 ohms-per-foot. However, some OEMs have recommended different maximum resistances. Use between 10,000 to 12,000 ohms per foot as a starter.
“Fuel / Petrol / Oil problems & Reminders” If fuel is left un-used for a prolonged period, then the fuel can become ‘stale’ over time. When the engine is attempted to be started, the stale fuel can wet foul the spark plug and thus fail to start your Lambretta.
If your using leaving fuel in the tank for short period of time (or new fuel), remember to rock your Lambretta Left & Right to remix the oil with the fuel.
General Info on Fuel & Oil
The use of leaded fuel does not really affect Lambrettas, other than there being more heat build up.
Lubrication of the engine is carried out by the fuel and oil mixture.
Most people report a run a 4% mix being required. Please see the Fuels and Oils page for further information on this located here: (Lambretta Fuels & Oils Link)
The carb float sticks often. Especially if you have old fuel and oil sitting in the float chamber for a period of time, so the carb may require cleaning ever so often to stop this from happening.
The Lambretta LD 1950’s manual:
“Additional Resources Section” LCGB Checking Your Ignition http://www.ilambretta.co.uk/ignition.html
Lambretta Workshop Tech Center http://www.lambretta.net/lambretta-tech-center.htm#sparkfail
General Fault Diagnostics: https://www.youtube.com/watch?v=pBoI6dcYt5A
Converting 6V to 12V https://www.matchlessclueless.com/electrical/lucas/12v-conversion/
Under review when I get time