Ignition system Triples CDI and BTZ and late SFC

Unlike the owner complaints received on the Triple alternator, those for the early ignition system were not really anyone's fault. The equipment supplied by Bosch for the Triple was of good quality and was certainly fit for the task in hand. It worked on those early machines in southern Europe (warm and dry) but not on those in northern Europe (cold and wet). Eventually Bosch and Laverda working together found that it was Britain's damp climate which caused the problem. The Triple's 'black box' (neither black nor a box) suffered internal condensation and the thyristor within failed. The design was sealed differently and turned upside down and the problem went away. (The Slater Brothers have stated that every UK imported Triple fitted with the early black box has now been retrofitted with the redesigned and reliable unit).

Let me recap, now that I have overcome the politics of the situation.

Most Triples to date have been fitted with a Bosch manufactured CDI (Capacitor Discharge Ignition) system which is essentially an ultra-reliable, super efficient maintenance free system. Bosch now describe it as their MHKZ system. The early 1000 machines up to frame number 3051 were fitted with the unreliable black boxes. These black boxes had their connections on the top side. The new reliable unit had its connections on the bottom side. This system produces high tension current from generating coils on the stator plate inside the flywheel magneto which then shoots it to the black box via the triggering mechanism which then shoots it off to the spark plugs — put crudely.

From mid-1978 on the 1200s and November 1978 on the 1000s, another system has been used.

This is manufactured by Bosch (although the HT coils are supplied by Nippon Denso) and is called the BTZ system. (Batteri Transisto Zündung ignition). This system works on a low tension current being supplied from the battery to two Bosch CDI amplifier units and then through two HT coils (ND) and onto the spark plugs. The stator plate mounted coils amount to triggering mechanisms. This too is a very reliable and maintenance free system.

I cannot over stress that with certain provisos both Triple ignition systems are very good and will not tax the owner.

NOTE: This sub-section will also describe the starter freewheel mechanism because it sits behind the flywheel magneto.

The first description necessary here is to explain the ignition systems' fitment. For whatever reason you are removing or fitting ignition components you MUST always disconnect both terminals of the battery. It has been known for two wires to touch, even as far away as the headlamp, and for the black box to blow!

The magneto flywheel removal has been described in the alternator sub-section; so has the stator plate removal. Remember that on that stator plate are the two triggering mechanisms; these are known as pick-ups to the factory. Remember too that the system used on the Triples is really a twin cylinder system; the two outer cylinders both spark together even though only one is actually igniting anything. With the stator plate removed you can change the charging coils but you must replace the stator plate complete with both triggering mechanisms if any one of these components has failed.

All that is now left on the crankshaft, which affects the ignition system, is the ignition trigger sleeve or impulse cam. On early machines before frame number 2820, the impulse cam was a push-on fit onto the crankshaft with a spring behind the flywheel and a tab inside the flywheel hub to make it rotate. It should be fairly straightforward to pull this impulse cam off. Go gently; you should be able to manage without a puller. On machines after frame number 2819 the impulse cam is located by a small alien (grub) screw.

NOTE: In terms of removal and assembly procedures, the CDI and BTZ systems are similar in this particular area.

Replacement of the impulse cam and complete stator plate is very straightforward. You cannot go wrong provided you replace each component in exactly the same position from which it was removed. Align the mark on the stator plate with the TDC mark on the starter gear cover; it's at 1 o'clock. There is only one area in which it is possible to set things up badly and that is if the position of the stator plate, which obviously controls the ignition advance, is not in the right place. It will be necessary to use a strobe light to check it.

Turn the crankshaft until the mark on the flywheel cover aligns with the TDC mark on the starter gear cover. Now measure 36mm for CDI systems and 42mm for BTZ systems, on the flywheel outer cover. Make a mark on the flywheel and then make a second mark on the starter gear cover. Now make a third mark diametrically opposite on the other 'side' of the starter gear cover.

Connect a strobe light to one of the outer spark plugs, make sure all three plug caps are earthed, i.e. fitted to their respective spark plugs and start the engine. At 5000 rev/min the TDC (first) mark on the flywheel should advance 36/42 mm back to the second mark made on the starter gear cover.

If they don't align under the strobe light, stop the engine, pull the flywheel magneto cover, loosen the two screws which hold the stator plate and then move the stator plate in a clockwise directicifiiif the advance is more than 36/42 mm (to the left of the second mark), or anticlockwise if it is less than 36/42 mm (to the right of the second mark). Tighten the screw again, refit the flywheel magneto cover and repeat the operation. Stop when the setting is accurate. 36 mm is the equivalent of 29°, and 42 mm to 33°30' of the crankshaft at full advance. The third mark on the 'other' side of the starter gear cover helps you to line up the two necessary marks with'the engine spinning at 5000 rev/min when reading under a strobe light. A tolerance of ± 2.5 mm is permissible. Remember that strobing is not necessary if your original stator plate and starter gear cover marks are accurate.


Mbi Ignition Sytem Ans Cycle

Laverda's method of checking the ignition advance on a BTZ equipped Triple: the numbers carry the same caption as the CDI machine

Laverda's method of checking ignition advance or a CDI equipped Triple: 1 is the existing mark on re flywheel, 2Jg the TDC marking, 3 is the Igmt or advance marking and 4 is the fresh mark diametrically opposed to 3

The starter freewheel (from a Triple, although the

Twin's is identical) showing the two major components with the plungers and springs in place

The components of both models starter freewheel -lubrication is essential

Laverda Jarama

The very reliable Bosch black box used on CDI ignition The other side of the CDI black box. Note the frame machines. This machine is a Jarama ' brace and earth wire

Laverda's method of checking ignition advance or a CDI equipped Triple: 1 is the existing mark on re flywheel, 2Jg the TDC marking, 3 is the Igmt or advance marking and 4 is the fresh mark diametrically opposed to 3

The starter freewheel (from a Triple, although the

Twin's is identical) showing the two major components with the plungers and springs in place

The components of both models starter freewheel -lubrication is essential

Laverda's method of checking the ignition advance on a BTZ equipped Triple: the numbers carry the same caption as the CDI machine

Starter gear

Behind the stator plate of the generating/ignition system is the starter gear cover just mentioned and the starter gear. The cover is held onto the crankcase by six setscrews — but the major problem is the large nut (left-hand thread) on the crankshaft which hinders the cover's removal. You rsust hold the crankshaft in the traditional manner but preferably use the factory special taol :::: ¿032;. undo the nut and remove it. (The nut has combined seal land). The cover can now be remored with its gasket once the six setscrews are removed.

The cover houses an outer bearing for the crankshaft which may make it stiff to slide off. Be eende with it.

What should now be exposed is the starter freewheel on the crankshaft with the starter idler ¿ear. with the starter drive gear bushing in the crankcase. The starter freewheel is a push-on splined fit to the crankshaft with the starter idler being unsplined. Two screwdrivers will get it off. The starter drive gear is also simply pushed on, although it may be shimmed. All these components are quite straightforward and easily assessed for quality. The starter freewheel works in the same way as that for the Twin, described in the Maintenance section. (It should be lubricated with engine oil mist).

Replacement of all the aforementioned components is quite straightforward and is an exact reverse procedure of their removal. Use a new gasket and use a soft gasket cement for the cover of the starter gears. Check the outer cover's oil seal. Replace that if necessary in the normal way.

Other ignition components — CDI

The CDI system is the simplest of the two when it comes to components. There is an engine stop relay — in its earliest form it was a Bosch silver box which fixed onto a rubber relay support. In fact, it was a push-on fit to the relay support. Later machines were fitted with a Bosch black plastic 'tube' which hung from the top frame tubes close above the carburettor bodies. Both these switches require a stable environment and must not be subject to excess vibration. That is why the box type is rubber mounted and the tube type is loosely tied to the frame tubes, and free to move. (Early 1979 machines may use the silver box and not the black tube, however).

It is not possible to test these switches — they work or they don't If you doubt their efficiency or reliability bypass them and see if your engine will then start. Look at the wiring diagram first, however.

* The black box is the only other piece of ignition equipment left. As already described there have been two sorts. I am going to assume that you have the modified black box — the one with its connections on its underside, when mounted on the machine. The black box itself mi^st be rubber mounted on the three point special bracket. These black boxes are very, very expensive — you must follow these golden rules.

1. If your are working on the machine, and this includes almost any task where you will touch electrical wiring — disconnect the battery.

2. Never turn the engine over with the ignition key switched on with the spark plug £IT leads unearthed. Connect them to the spark plugs, with the plugs in the cylinder head. Then if they are not earthed — you will blow the black box!

3. If you are angry and think that the black box has blown, check all the wiring for proper connections and then check the fuse box.

The ignition circuit runs through the fuse carrier. Make sure the contacts are clean and that there is no oxide build-up there.

4. Check that the red cable leading from the stator plate up to the black box, via the electrical connecting block under the tank, is well isolated and protected.

5. Check the engine cut out relay.

6. Finally check the block connection going into the black box. As the system is very water sensitive you must make sure that this connection is clean and water tight. To achieve this, pack the connection with Bosch grease 5 700 005 005 or Total Nyctea 3 (other similar grease will work).

Now read on. The only way to check the function of the black box is to fit it on the machine, or n a test rig (not practical), and connect it to a flywheel magneto known to be perfect. Remember that the spark plug leads must always be connected to earthed spark plugs when the crankshaft is turned over with the ignition on otherwise thyristors in the black box will be overloaded and instantly destroyed. The ignition advance is 29° at 5000 rev/min but practically full advance is reached at 1200 rev/min. The retard/advance jump is 14° -16° and is regulated by a sensor in the black box that reacts for changes in tension with increased engine speed. The stator plate ignition coil can be checked for short circuits with a normal test instrument. The resistance, with the instrument connected between the red cable and earth should be about 3000 Ohm. This coil can be ruined if exposed to high temperatures, then giving starting problems or misfiring. If it looks brownish or has a burnt smell, chances are that it has been overheated and that the shellac insulation has melted.

The gap between the pick ups and the impulse cam should be 0.15 - 0.20 mm. The pick ups are made in unit with the stator, though, and thus the gap can only be adjusted by grinding away or adding material to the impulse cam. If the cam to pick-up distance is not correct it can be the result of a slightly bent crankshaft, i.e. after an accident, or a badly worn ball bearing on the starter gear cover. The pick-up resistance between the two outgoing cables, should be around 60 Ohm. On machines with frame numbers lower than 1270 you measure this between the one pick up cable and earth.

Failures in the engine stop relay result in the engine not starting or not stopping, or even misfiring on either both outer cylinders or the middle one. To check it undertake the test just described. The ignition works without this switch but the engine cannot be stopped by switching off the ignition!

Finally, make sure that the inside of the flywheel does not touch the coils on the stator plate. There must always be a small tolerance of 0.10 - 0.20 mm.

Remember one last thing — if your engine just stops and cannot be restarted on either one (middle) or two (outer) cylinders, then the failure is very unlikely to be in the black box. There are two separate coils in the black box and'it is almost unheard of for both to fail simultaneously! Go back to my first checks.

NOTE: It is not possible to bump, tow or push start CDI machine with a discharged battery.

Other ignition components — BTZ

The BTZ system is a low tension system supplying current direct from the battery to amplifiers, through the triggering mechanism on the stator plate and then into a pair of Nippon Denso coils and so onto the spark plugs. All the component parts are of good quality, each are only replaceable and not repairable, making testing other than by substitution virtually impossible — the system works. There is but one possible drawback — the machine" will NOT start, even by bumping, pushing or towing, if the battery is discharged. Add this factor to the lack of a really adequate alternator generating system (already established elsewhere in this section) and all looks doomed. The system does work! The alternator on the BTZ systenj now has enough energy to charge the battery because it is not feeding the ignition system direct, as on the CDI system and the system is balanced at 3000 rev/min instead of 3500. The pay off, and there is one, is that the component parts of the BTZ system command an enormous price. It would not be unfair to say that the BTZ component price list would'double that of the CDI system. There are but two pieces of advice here — don't fiddle with components you don : understand and always have a battery charger to hand.

Fortunately there is nothing really complicated, and most of the advice given for the CDI system applies.

There is no engine stop relay because :t is a low tension system and the ignition switch cuts current in or out of the system.

The two amplifiers, made by Bosch, need to be looked after — their mounting bracket is rubber bushes against vibration. They too have connecting plugs which require protecting with the same anti-oxidising grease already suggested for the CDI's black box connection. On their same bracket is mounted the generating system's regulator (BTZ ignition systems come hand in hand with a 150W alternator which swops the rectifier for regulator proper — remember more generated current is now being used to charge the battery on this system). On top of the bracket is the fuse box — the same precautions apply to this one as they did to the CDI fitment. A double (outer cylinders) and single (middle cylinder) coil sit side by side under the nose of the fuel tank. They need the up front cooling and must also be anti-vibration mounted. These are very reliable Nippon Denso 'ceramic' coils. Positively no maintenance! Each coil comes integral with an external

The BTZ ignition system coils. Note the difference in The other BTZ coil. The white cylindrical component to the frame compared with the CDI equipped machines the right of the coil is a resistance
Laverda 650 Vicenza

Only BTZ equipped machines use this yellow wiring which passes through the rear mudguard

Behind the right hand side cover of a BTZ equipped machine. It's one of the amplifiers which cost so much but which are very reliable

Laverda 650 Vicenza

The battery has been removed from this BTZ equipped The previous shot again but from further away with the machine. In the bottom left hand corner is the fuse fuse box cover removed and the battery replaced box next to an amplifier (finned box) with a relay in the centre

Only BTZ equipped machines use this yellow wiring which passes through the rear mudguard

Behind the right hand side cover of a BTZ equipped machine. It's one of the amplifiers which cost so much but which are very reliable

The gap between the trigger and impulse cam should be measured at A (SFC using BTZ ignition)

With the engine at TDC (i.e. PM aligns with the mark on the crankcase on the other side of the engine) the two marks shown here should be in this position (SFC using B TZ ignition)

Trigger Impulse Coil

The BTZ ignition SFC uses a coil positioned thus

Laverda 650 Vicenza

The electronic ignition blister on the SFC primary Smiths Instruments' bulb replacement from below cover. It's a magnesium casing

Trigger Impulse Coil
Here's the BTZ-SFC's black box with a warning to fill its connector with the appropriate grease

resistance. Keep all the components clean and properly mounted. You cannot cheat and alter their specification or location without leaving yourself open to failure and then expense.

Strictly speaking it is not possible to swop CDI for BTZ — the factory list two different frames! The BTZ frame allows you to fit the nice plastic tool tray under the nose of the seat.

NOTE: Because of the construction of the BTZ system, its connections etc., you cannot test it at home. It works or it doesn't.

* For those few SFCs with Nippon Denso's PK ignition system here is an explanation of its workings. (PK means pick-up, or trigger unit). In a nutshell, the system is virtually the same as the Triple's BTZ. It is a low tension system fed from the battery; in other words the machine will not start if the battery is discharged. Current comes direct from the battery to an amplifier which then pushes it through the triggering mechanism into a high tension coil and so to the spark plugs. The triggering mechanism sits in the same place in the crankcase as do the contact points on a more conventional Twin although the parts are not interchangeable. An impulse cam fits onto the end of the (different) crankshaft via a spline and a washer and nut. There is only one trigger which 'fires' every rotation of the crankshaft. The single coil, with two HT leads, also 'fires' every rotation with, of course, both spark plugs firing each rotation although each plug takes it in turn to actually ignite any fuel mixture.

From a maintenance point of view the system is fool proof. There is little to adjust. Fitting the impulse cam and triggering mechanism is straightforward and once accomplished should provide utmost reliability.

Remove the dynamo cover and the trigger cover. Turn the crankshaft on the dynamo side until the PM mark on the starter freewheel aligns with the mark on the crankcase. (The impulse cam can only fit one way onto its spline). The trigger has a two screw fitting. With the engine at TDC, positioned as just described, align the horizontal mark on the trigger with the horizontal mark on the end of the impulse cam. Tighten the trigger and then turn the engine just a fraction until the centre of the cam, of the impulse cam, aligns with the horizontal mark on the trigger. Now measure the gap between trigger and impulse cam. It must be between 0.1 - 0.2mm. Adjust the trigger accordingly but do not lose proper alignment.

Now read the sub-section on the Triple's BTZ ignition. Take care of the amplifier and coil in the same way. Grease the connector of the amplifier. Make sure both amplifier and coil are anti-vibration mounted.

NOTE: The Nippon Denso coil used on the SFC does not normally provide reliable starting. It makes a lot of sense to change the one ND coil for a pair of proprietary, high quality coils and then wire them in parallel. It is not possible, not sensible, to fit electronic ignition to an 'ordinary' Twin. It is not necessary, such is the quality of the original, conventional parts and if contemplating the SFC system you will need to change the crankshaft!

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  • Valentina
    How to laverda 750 ignition setup?
    4 months ago

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