This article is not a fault-finding article on how to repair faulty ignitions.
It is to try and identify your ignition system, point out their faults and help your tuned engine become more reliable.
The ignition system would control how a tune, carb and exhaust would work as a package.
A poorly set up ignition would mean the tune doesnít work correctly and would become unreliable.
All Lambretta engines need a good ignition system as much as it needs a piston, crankshaft or exhaust system.
This is a fact and it is a very important part of the engine especially a tuned engine!
From the beginning of the Lambretta engine the ignition system has always used the magneto points system.
As an easy explanation the flywheel has magnets embedded in it, as the flywheel turns it creates a magnetic field around coils located on the stator plate, this generates power for the lights and ignition.
This type of system on Lambrettas has always used contact points control when the ignition / spark plug fires.
Some systems used batteries and some did not.
The basic system has been modified from the model ĎAí right through to Grand Prix 200.
There have been variations on each system over the years but for tuning purposes they were all basically the same.
The early engines have four-pole flywheels and stator plates, this means they had four magnets within the flywheel creating four pulses, hence the four pole system.
The later versions were modified to six pole ignitions, i.e. six magnets in the flywheel.
SERIES 1, 2 AND EARLY SERIES 3 (four pole generators)
We havenít covered much of the early models in the tuning sections.
Most of the tuning is relevant and still works the same.
There have been four early systems used, these systems used brass flywheels and if still running could work fine on very mild tuned engines, especially engines that have kept their original carbs and exhausts as these limit the amount of power and revs that that engine will do!
Any ignition system would have to be in tiptop condition to stay working on a tuned motor.
These systems when working could be fine on a standard engine, but lack power in the lighting department, this can effect the ignition system and cause problems with firing of the plug when the lights are on!
These systems were quite inferior especially when used with high revving tuned engines and would be best at least converted to the Series 3 points type.
Changing any of these systems can be done by upgrading to the later series 3 type systems. This would require changing the relevant parts needed for the system to work.
SERIES 3 (6 pole generators)
These systems were fitted to all of the later type Lambretta models. There have been variations to these models.
There were two types:
1. The AC system, (alternating current) i.e. non-battery. These had 4 different coloured wires, purple, green, brown and pink.
2. The DC system, (direct current) i.e. battery system. these had 4 wires, 2 yellow, green and brown.
And there were two variations:
1. The Li, SX, TV type using the thin crankshaft taper.
2. The GP type using the fat crankshaft taper.
Flywheels were not interchangeable between crankshafts but all other parts were basically interchangeable.
Early systems used single spring points. This was one of the main tuning failures as the single spring was not strong enough to take the extra revs of a tuned engine, this caused points bounce and misfires at high revs.
This misfiring may have taken place at revs as low as 5000rpm.
The later systems used double spring points this, within reason, cured the problem of pointís bounce.
Other factors also affected the ignition system with regards to tuning.
For most Lambrettas UK models or imports the 6-volt, 6-pole system is the most common.
Parts are freely available new or second hand.
Towards the end of the Lambretta production range, the Grand Prix 200 electronic scooter appeared with a totally new ignition system.
The flywheel and stata plate looked very similar to the original points system but instead of points and condenser it had an electronic black pick box (chopper) a different low tension coil and now had a different ignition coil which was square shape and red in appearance.
The system had 6-volt lights, and to my knowledge the ignition was still 6 volt.
From the outside the flywheel looked identical to a GP flywheel.
The only difference were that two magnets had prongs than over lapped each other, this was the magnetic chopper controlling the spark.
The flywheel boss had no cam to open the points but I have seen flywheels with the cam type boss.
In my youthful days I seemed to be surrounded by old electronic scooters, they were all unreliable for some reason.
The main fault seemed to be the red ignition box, twenty years ago they fetched and held their money, even more so parts today.
It was possible to change to the later Vespa electronic coil if wired up different.
Other faults which effected the system from working was the stata plate these seemed brittle and fell to pieces (probably the owners fault).
As with all GP type flywheels used on fast tuned engines the die cast flywheel would crack around the boss and break!
The GP system came out in the late 1960ís, Vespa didnít bring out an electronic ignition until the-mid 1970ís with the introduction of the Rally 200, and this system was totally different!
But in the late 1970ís Vespa brought out the PE200 Scooter with electronic ignition nearly 10 years after Innocenti!
Ducati Electronica who made the GP system again made the Vespa system.
Basically the system resembled the GP one, the lighting was now 12volt and had a black ignition box instead of red.
By using the Vespa parts the Lambretta system could be repaired to work very well.
With the end of Innocenti, ignition system development ended for a while.
Both Scooters Indian limited and Servetta Spain took over production from the Italians.
Early scooters used Innocenti left overs, as these ran out India and Spain produced their own versions of the later Italian points systems.
As stated the Spanish factory used up old supplies of Innocenti SX / LI ignitions.
They then had their own systems made by the Spanish firm Motoplat.
These systems looked similar to the Li systems but flywheels and stata plates were different and parts were not interchangeable.
Spanish points had only a single spring and again tuning a Spanish engine had the problem of pointís bounce at relatively low revs!
The main downfall of the Motoplat systems was reliability, if they worked they worked well, but most were unreliable only working when they wanted, especially in the rain!
The early AC system could blow bulbs very easily and it has been known to fit 24 volt bulbs all round to cure bulbs blowing!
Motoplat had variations of their systems, they introduced 6-volt and 12-volt lighting and used different regulators and wiring set ups, again very little was interchangeable with the Italian or later the Indian systems.
All these systems had no interest from the tuning point of view.
The Motoplat points system used different points and condensers and were not interchangeable with either the Italian or Indian systems.
The pointís system flywheel weighed approximately 3kg; similar to the Italian item.
Using this weight on tuned Lambrettas, especially Spanish engines with Spanish crankshafts, problems could occur as the flywheelís weight could cause the crank taper or crank pin to snap!
In the-mid 1980ís Motoplat introduced an electronic ignition system that fitted the Li type crankshaft.
This system worked well, both lighting and ignition were excellent and was much improved over the points system!
Unfortunately its downfall for tuned engines was again the flywheel weight.
These flywheels weighed 3.2kg, by far the heaviest flywheel produced for Lambrettas.
Although very well made it was far too heavy, even heavier than a standard Ducati flywheel.
The problem with heavy flywheels on SX / Li crankshafts is that the crank tapers are not fat or strong enough.
The flywheel weight can snap crankshaft tapers and crank pins.
This seemed more so with Spanish crankshafts as the crank webs and crank pin didnít seem as strong as the Italian versions.
The flywheel had enough meat to be machined down safely without affecting the cooling fins or without the need for a plastic fan, but the crankshaft was still prone to failure.
To identify a flywheel was easy, look at the cut out inspection holes around the flywheel nut, this was the only flywheel with triangular holes for a flywheel holding tool to fit.
The coil was different to other systems, still red and similar to the MSC item but not interchangeable.
The regulator looked similar to the Vespa regulator and again was not interchangeable.
|The spanish motoplat Li Electronic flywheel and stator.|
|The Spanish motoplat electronic flywheel. Note the triangular holes which require a totally different flywheel holding tool.|
|View of the back of the flywheel.|
|The motorplat 6V Li electronic stator.|
|The back of the motoplat Stator.|
As stated the Indian factory used up left over ignitions from the Italian Grand Prix range.
As parts ran out SIL introduced their version of the Italian systems.
The main difference was the flywheel.
This was changed from a two piece die cast item to a steel and alloy type using nine separate pieces riveted together (not including the rivets!).
It has been known for rivets to shear and fins explode!
The stata plates were altered to either 6-volt or 12-volt lighting with their various versions of electrical accessories.
Some systems used batteries some didnít.
The Indian systems had such a bad reputation for unreliability.
The points and condenser were unreliable but could be changed to the Italian type, as these were interchangeable.
Basically because very little was understood about the Indian systems people tried to set up as per Italian ignitions.
But the Indian Ignition needed different points and plug gap, and also used a different coil!
If setting up as per Innocenti then problems occurred!
It was and is with out doubt that Indian electrics are not as well made as the Italian versions and this is still true to day!
They know this and still do nothing about it!
MIDLAND SCOOTER CENTRE. DJ MOTOPLAT GRAND PRIX ELECTRONIC IGNITIONS
In the early 1980ís MSC found a supply of Motoplat electronic ignitions originally fitted to a micro light aircraft.
These systems used a full 12-volt lighting system with lots of power, you could run fog lights from the system!
The system was a battery type and used a standard 12-volt Lambretta battery.
With use you would find the battery burnt out regularly!
Ideally a larger battery or two batteries needed fitting to cure this.
The ignition had no advance feature and used a fixed firing point.
It used a coil similar to the Spanish Motoplat systems but was different and not interchangeable.
These systems looked like no Lambretta system used before or after (apart from the later Servettas) there was a limited amount available, to date they are so rare I havenít come across any of these systems on working Lambrettas.
The last one I had was used on my sprint engine to good effect as the flywheel had some weight but not too much.
The flywheel weight was approximately 1.4kg.
It had no cast fins on it so a plastic fin was needed, this was no problem as the flywheel was nice and large and had a flat area to locate a plastic fin too.
The stata plate looked like no other before, as it was sealed in a red epoxy (similar to the later Jet item) a special alloy plate was made to suit it to mount inside the Lambrettas mag housing.
Also the flywheels taper was machined to fit only the GP type crankshaft.
Fitting a peg through a small hole in the flywheel set up the ignition timing, this then located into the stata plate, the same as the later Servettas.
A special stepped woodruff key was required for this system or the flywheel could be modified to take a standard woodruff key.
The main down fall for the system was that the battery would lose charge over a few nights and a special ignition switch was required to cut the earth out, stopping this discharge.
Or alternatively a cut out switch could be fitted to the earth strap of the battery.
We have come across a few lately and they were really well made, shame the supply dried up.
VESPA PX AND PE IGNITION CONVERSIONS
In 1985 I worked at Beedspeed scooters and was introduced to the delights of Vespas!
One thing I saw straight away was the Vespas ignition.
As I looked at the PX and PE statas I realised they would go straight into a Lambretta engine.
To do this it required the Vespa stator parts swapping on to a Lambretta stator.
This could be done in 2 ways.
1. Unsolder all wires, bend over the coil tabs and remove each coil and part individually, do the same to each stata then rewire the Vespa parts onto the Lambretta alloy part of the stata.
2. Another way was to leave all the coils intact drill out the rivets securing it to the alloy back plate then swap that onto a Lambretta stata, then rewire it.
You could do this to a PX points stata very easily.
By swapping the PX coils and leaving the Lambrettas ignition coil, points and condenser, this gave your Lambretta 12-volt lights (the PX regulator needed using) and you could use either the Lambretta or Vespa coil systems depending on how you did it.
The total Vespa conversion was best, as the ignition coil was more reliable that the Lambretta item.
Doing this conversion would use existing points and Lambretta 6 pole flywheels.
This system was very good and cheap but still used points with their problems on tuned Lambrettas.
The other way was to convert all the PE electronic system over on to the Lambretta stata plate and use a GP electronic flywheel this again was very easy but the flywheel was getting hard to find.
I looked at the PE flywheel swapped the cam, machined the flywheel down and fitted plastic fins, after a lot of timing and strobing, the system worked.
The main big problem was the Vespas flywheels firing point.
The Vespa system is out of line with a Lambretta so they fire in the wrong place!
You then need to re-drill and tap 3 more holes in your mag flange to get the stata in line with the firing marks.
Both PX and PE conversions worked but took a lot of time!
Given the hassle factor and difficulty in obtaining spare parts plus the factor of ignitions being totally out of time I pulled out of using this system in 1987!
Anyway what was the point in doing a difficult labour intensive system when the AF electronic system came out!
AF RAYSPEED, ELECTRONIC IGNITIONS
In 1987 AF Rayspeed introduced a new revolutionary ignition system.
This system we found to be the best, it fitted with minor modifications, and it worked and gave some of our engines the best horsepower.
Sadly flywheels and stata plates have dried up and will never be replaced.
There were two systems used, the AC (non-battery) and DC (battery) types.
We found that the DC system lost charge in the batteries very quickly and soon we converted to the AC system, this got rid of the battery, which we believed to be very impractical.
The AF system was a cross between the Ducati system introduced for the GP electronic, Vespa PE system and the J range.
The basic difference between the other systems seen at the time was the flywheel.
The flywheel was alloy and much smaller and lighter.
It resembles a J range flywheel except the cam was now GP and had the two cross over magnets with-in the flywheel for the pick up points.
The flywheel had three cut out windows compared to other systems and required a new flywheel holding tool.
The flywheel used a dust cover from the J range also.
Many people used to jam bits into the fins to tighten the flywheel up, this always resulted in broken fins.
These flywheels are now getting quite rare and when we see them some fins are usually missing.
In some circles this flywheel was considered too light at approximately 1.4kg, most engines required a faster tick over speed and if you didnít get it right stalling the engine was easy.
The light flywheel caused more vibration low down but the advantage was better throttle response.
The two types of statas (AC and DC) looked very similar, the low tension coil and pick up were the same but charging coils were different and were wired up differently.
The easy way to identify them was, the AC system had 4 wires coming off it and DC system had 6.
The AC system used a regulator the same as Vespas with 3 spade connectors, the DC system used a rectifier with 5 spade connectors.
They both looked similar and were the same to look at but were not interchangeable.
Both systems used a black electronic coil as per Vespas and were all-interchangeable.
Ignition timing was done by the original method set by Innocenti of the raised lines on the pickup box and notches on the flywheel if done correctly ignition timing was perfect!
The lighting system was now 12-volts and required the bulbs and horn changing over.
Some modifications were required or problems would occur.
Lately SIL have introduced their own electronic ignition system for the GP models (and in the last years for the SX models).
This system is a across between the Innocenti GP, the PE Vespa and AF system.
The Indian system is the only system available today so we are stuck with it!
The major difference with the system is the flywheel.
This was changed from a die cast item to a steel and alloy type riveted together.
The fins are alloy, the flywheel is steel and the magnets are bolt in loose types.
This flywheel is riveted, bolted and glued together.
The flywheel is very heavy at approximately 2.6kg, more so than a GP electronic type.
This can cause problems especially if flywheels are not tightened tight enough.
We find the flywheel is too heavy for SX and Li type crankshafts as the taper is thin and tends to shear or spin.
The GP flywheel has been under cut on the cam and these can shear off, MB Developments weld around this area and this cures the problem.
It has also come to our attention that the rivets holding the cam to the steel flywheel comes loose also, so MB Developments now weld these together with the kits we sell.
The Indians in their wisdom made the flywheel fins longer to aid cooling, this we have been told from the designer does nothing for cooling as no extra air can get between the fins.
A whole new longer flywheel cowling was made.
But the UK way is to machine down the fins to original size and use a standard flywheel cowling.
We have known the alloy fins to explode away from the rivets.
If this happens expect our cowling and mag housing to go with it.
The stata plate comes from the factory wired up differently to before as they use a different regulator and electronic coil.
The stata should be rewired correctly and supplied with an Italian type regulator and coil.
The quality of the Indian stator is very poor, in standard form they are not too reliable!
The main fault is the earth straps are not tight!
The pick up coil fails regularly in standard form.
MB Developments know about all these faults, it is very annoying!
All electronic systems sold by MB Developments are the GP type and have these modifications done before sale.
|The MBD conversion to strengthen the Indian electronic flywheel.
If this isn't done the cam can split and the flywheel will fall off or the rivets shear and the flyhweel falls off.
|The cause of the problem is the factory machining a 90 degree corner into the cam creating a weak point.
Our cure is to mig weld around the cam to put a strengthening bead there.
This has cured the problem.
|Indian electronic flywheels are very heavy at 2.6kg.
By carefully machining away as much as we dare the flywheel weight is reduced to a more sensible 2kg.
|The 2.6kg flywheel is fine for low down tickover and smooth running but for more performance and improved throttle response we lighten the flywheel as an option.
There isn't much more to take off but you don't want to over-lighten your flywheel as this can give you problems with getting your bike to tickover and maintain a steady speed.
All MB Developments ignition kits include:-
To reduce flywheel weight MB Developments offer a flywheel lightening service.
This can reduce weight down to approximately 2.0kg helping throttle response.
MB Developments offer these spare parts separately for the Indian electronic systems.
INTERCHANGABILITY OF AF, VESPA AND INDIAN SYSTEMS
Given the three electronic ignitions usually fitted to a Lambretta, parts are interchangeable.
The main failure of electronic systems is the pick up box and low-tension coils.
Indian pick ups are available but are not as good as the Vespa item (the only one MBD keep), the only low tension coil available is Indian.
Vespa do not offer this as a spare part, they only offer a complete stata plate.
The Vespa style regulator is usually used on all systems, these look different to the Indian ones, but both work if wired up correctly.
The Vespa style regulator come in different wattage ratings, they vary slightly in size and can be made in Italy or the Far East.
The ignition coils (or CDI box what ever you want to call it) usually come in black but there has been some available in different colours.
The colour coming through at the moment is Blue, there are no differences in their workings and ignition coils are interchangeable between all systems.
Indian, AF, Innocenti and Vespa flywheels are interchangeable with the same stata plates but care should be taken timing them up.
Any system can be repaired with the parts available today.
Over the years Motoplat has produced a number of race ignitions suitable for Lambretta engines.
Looking at a Lambretta flywheel it spins clockwise, most modern race style engines spin anticlockwise.
Some Kart engines spin the same way as a Lambrettas making them ideal to convert, the only problem was they were race systems and had no lights.
Two types were common
Major advantages of this system allowed an auto advance box to be fitted, these came in different degrees of advance to suit different engines.
Or they could be used as standard fixed ignition.
As these were race ignitions and came from small capacity racing Karts the flywheel were small and only weighed between 1.2 and1.5kg.
Plastic fins were also required on air-cooled engines.
In the 1990ís Motoplat went bust and ignitions became hard to find for race use.
Towards the end of the 90ís a company called Ital systems remade the clockwise race Motoplat system and it is now freely available for race engines but not for road engines unfortunately.
In 1987 I developed a Japanese ignition system using old Suzuki parts, this system was absolutely brilliant.
It had a built in advance retard feature and gave the scooter a pulling power rarely ever seen today.
It was this system that made me a fan of any ignition system with an advance retard feature (also called auto advance) this system used 12volt lights and a battery, the down fall was availability of second hand parts and new parts were unbelievably expensive!
In the 1990ís I developed a Japanese race ignition for our race team, again this worked well but second hand parts were hard to get and new they were very expensive.
Other dealers have used other race systems.
One very common one was the total loss system, this used an electronic chopper for igniting a cars coil energised through a battery. Once the battery went dead so did the spark, not good on a road bike.
IDEAL IGNITIONS AND AUTO ADVANCE / RETARD IGNITIONS
Ideally a tuned engine needs an electronic ignition.
It aids starting and produces a better spark keeping the engine firing in time with every revolution.
To advance further on this, the ignition should have some type of advance and retard feature, which varies the firing point depending upon revs.
All modern engines run such ignition systems but not the traditional Lambrettas or Vespas.
(Early LD systems used a mechanical auto advance system in the fifties but Innocenti didnít carry it on to other models).
As already stated some oddball ignitions had this function and usually the quickest race scooters found them to be an advantage.
For years I wanted to find a road system to use an advance retard feature, to no avail.
But in 2001 at last through looking and trying we finally found an electronic coil, which was a direct replacement to the Vespa electronic coil.
This coil could give nearly 10 degrees ignition advance depending on how much your engine revved.
This was not a lot compared to the Motoplat system that could give around 25 degrees advance.
Our early coils were red or blue, but after some testing we found they only worked on the Indian steel flywheels.
For some reason they did not work on either the AF flywheel or a Vespa flywheel.
And in some cases only 70% worked on Indian flywheels.
For this reason we disappointingly took these coils off the market.
Basically if they sparked then they worked and worked well.
We found with testing that on an average road scooter you got between 6 and 4 degrees, not much compared too the Motoplat system but just enough to feel the difference.
For 2002 we have found and introduced another CDI and separate coil set that works on all systems including the AF, Indian and Vespa flywheels.
It still only gives a small advance but is worth it on most engines.
The new MB Developments auto advance retard ignition coil kit.
It has been, over the years, a fad to lighten flywheels and fit plastic fans from electric motors.
This is quite fine and very normal for racing engines, unfortunately plastic fans donít have a very long life expectancy, especially if some thing goes into the flywheel cowling.
Racers could always take spare fans already predrilled, if a fan went on the track you could always limp back to the pits and race again.
As this article is aimed at high mileage road users, plastic fans become hard to squeeze into toolboxes or kit bags making them quite impractical.
Iím not saying that you couldnít get high mileage from a plastic fan, you could but it was that unknown factor and many people seized their engines not knowing the fan had disintegrated!
A flywheel nut on a Lambretta is a left handed thread, the reason for this is, as the flywheel spins clockwise it is tightening the nut, if it was a standard right handed nut then the flywheels rotation undoes the nut!
The only real way to secure a plastic fan would be to use small bolts or screws and wide washers to spread the load, using the same theory normal bolts would undo them selves and they did!
Loctite always helped this to stop happening.
Most flywheels donít leave enough metal area behind the fan to seat the fan correctly making life even worse.
The worst case of this would be the Vespa electronic conversions that I invented many years ago. I personally dropped this conversion for three reasons,
The most popular system using plastic fans was the MSC GP Motoplat system as used in the mid 1980ís.
The fan for this system was quite large and needed cutting down but usually lasted as it had a large flat area and plenty of metal to tap screws into it.
Standard Lambretta flywheels are quite heavy, the advantage of this is a smoother running engine especially at lower revs and tick over.
The disadvantages of heavy flywheels are a lack of response to the throttle and they will limit the amount of revs.
Over heavy flywheels cause crankshafts to spin out of line or in some cases as with the SX / Li crankshaft flywheel tapers and crankpins will shear!
This is the reason why MB Developments donít recommend SX / Li crankshaft and ignition systems in anything other than standard engines.
The worse case for a heavy flywheel set up was the Spanish Motoplat electronic system, which was used on SX cranks.
It was possible with this flywheel to machine a large amount of weight from it to make it more useable.
A lightened flywheel gives the advantage of throttle response, acceleration and higher revs.
The disadvantage of a lightened flywheel is the lack of inertia which at some parts of the rev range can be a disadvantage.
The worse case was possibly my 40hp sprinter fitted with a very light flywheel weight of .70kg, if there wasnít enough revs on when setting off the engine would stall.
But when setting off fast the engine just spun the back wheel giving nothing in-between!
Fitting flywheel weights helped to cure the problem, showing that too small a flywheel was no good.
The Indian flywheel is quite heavy at 2.6kg compared to an AF item at 1.4kg, which was a little too light.
An in between weight is the Indian flywheel machined down too approximately 2.0kg an ideal weight for any tuned Lambretta engine.
|MB Developments offer the complete "Dev-tronic" GP electronic ignition packages
Package 1 (Dev-tronic fixed) consists of:-
Please specify MRB0255 for package with grey wiring loom and MRB0303 for package with black wiring loom.
Package 2 (Dev-tronic advance) consists of:-
Please specify MRB0304 for package with grey wiring loom and MRB0305 for package with black wiring loom.
One side of the MB Developments electronic mounting bracket, shows the electronic coil tucked away where the standard coil would be.
No need to alter your frame or expose your electronic components to the elements!
|MB Developments offer the following electronic ignition parts, spares and sundries
Please E-mail us with any questions or comments.