Generator Twin dynamo and regulator

A Bosch dynamo (DC generator) is fitted to the front of the crankcase and is belt driven from the crankshaft on the right hand side of the engine. Effectively it's a car unit, similar to that used on a Volkswagen Beetle. Many questioned its use when it was introduced saying that it was even then outdated. However, it did last the production Lie of the Twin and is renowned for its reliability and power. Apart from its weight there can be few disadvantages. Dynamo belt replacement has been dealt with in the Maintenance section. The dynamo is clamped to the crankcase — the drive is covered by an outer cover which also covers the starter drive and freewheel. Remove the dynamo cover which is attached by four setscrews and washers. If you wish to work further on the dynamo, then disconnect the battery. To remove the dynamo, peel off the drive belt using a similar method to that described for replacing one. Undo the two electrical connetions and note which one goes where — they are not interchangeable because one uses a spade tag, the other a hook with its fixing nut not being fully removable from its stud. The dynamo straps onto the crankcase with two 'half-circle' straps mounted each end onto studs. Remove the four nuts and washers and pull away the dynamo with its end shield. The two supports remain on the studs in the crankcase.

Replacement is a straightforward reverse sequence.

Little can be done at home to a dynamo except for the changing of brushes and cleaning of the commutator. There is little point in attempting anything else on a dynamo — you can remove the pulley! That is done by holding the pulley :n a soft-jawed vice and then undoing the end nut. The pulley is keyed onto a removable Woodruffe ».ey.

The brushes are mounted on the inside of the end plate. To remove that plate, undo the two through-bolts (captive threads in the opposite end plate) and withdraw them. Carefully pull off the end plate then inspect the placing and connections of the two brushes. Their original length is 19mm — they need to be replaced when they are as short as 9mm. Make sure you remount them with the proper insulation.

Visually inspect the commutator. Then clean it with a fine emery cloth and re-cut the gaps between the copper plates, using a small metal file cfr hacksaw blade. Be sure to remove any dust with a petrol soaked rag.

Reassembly is straightforward.

The output of the dynamo is controlled by the regulator or control box. This is mounted away from the dynamo on a rubber strip in the centre of the frame under the fuel tank. Little can be done with it if it appears to fail for it is theoretically sealed. Special testing needs to be undertaken by an experienced auto-electrician. For him, however, here are certain details he could use. The field resistance is 3.5 ohms Output is 150 Watts at 14 volts Cut in speed is 1450 rev/min Normal current is 7.5 amps at 1700/1850 rev/min Maximum current is 11 amps at 2100 rev/min

The voltage measured at the regulator discharge should be between 13.8 and 14.8 ± 0.2 volts at a current loading of 2/3 maximum (i.e. 7.5 amps)

At 5500 rev/min the voltage should be between 12.7 and 13.7 volts at a loading of 16.5 amps. At the

The SFC's control box Is mounted in front of the The white box between the two top frame tubes in the battery because of the different frame and lack of air generating circuit control box, far from the dynamo but cleaner. This machine has been over filled with oil and close to the battery. It should be rubber mounted the breather (in front of the control box) has blown!

The SFC's control box Is mounted in front of the The white box between the two top frame tubes in the battery because of the different frame and lack of air generating circuit control box, far from the dynamo but cleaner. This machine has been over filled with oil and close to the battery. It should be rubber mounted the breather (in front of the control box) has blown!

drop of the intensity of 2.5 to 9.5 amps, the voltage will disconnect at 12.2 volts.

Once again it needs to be stated that the Bosch dynamo and regulator are very reliable and apart from the tasks mentioned here, little can be done at home. If failure takes place, seek professional advice. Tell that auto-electrician that in your case he will be working on a car-type generating system.

The GTL police model has sometimes been fitted with a belt driven alternator to provide a high output to power radio and other ancillary equipment when the engine is running at low speed. Under normal everyday circumstances this power is just not necessary, therefore alternator servicing is not mentioned here. It is practically impossible to change one system for another, and the cost is horrific!

Generator — Triple's alternator

In spite of what has been written and complained about over the years, the Triple's alternator still does not function in a manner that suits the rest of the machine's style. It is too weak and requires relatively high engine revs to reach full output. The problem is now satisfactorily solved on the latest machines with the day-on 20W side lamp bulb in the headlamp.

Bosch have now supplied a number of different components but because of the relatively low volume»of production they cannot develop a one-off component for Laverda at a price that anyone could afford. No other manufacturer really has anything else suitable in their range. The first unit fitted was a 100W, the second a 100/23W, the third a 140W unit and the current unit is a 150W (BTZ ignition only). The first three units did not have a regulator fitted but were helped with a Bosch rectifier. The last unit does use a regulator — this unit is the one fitted with the Bosch BTZ ignition, although it is itself still made by Bosch. Each type of unit is easily recognised because it is stamped with its output although otherwise they do look much the same. Remember that early alternators can be swopped for later ones although the 150W alternator, when used on a CDI machine, needs a rectifier from the 140W alternator, not the regulator. When you swop alternators make sure you swop rectifiers as well for they are different. The early rectifiers were little Bosch silver boxes, the later ones were slightly larger Bosch silver boxes.

It is not necessary here to delve into the history of the Triple's alternator and discharged battery phenomena, sufficient to say that you should buy yourself a battery charger and trickle your battery regularly on pre-1979 machines, depending how little your machine is used. Low speed use with the headlight on will discharge the battery and that is all there is to it.

The Triple's generating system is simple and one should not be frightened of it. It can be tested and repaired very easily. The alternator sits inside the alternator cover on the end of the crankshaft on the right hand side. Its cover is the one which will scrape the tarmac if you corner too hard. The cover is easily removed, the magneto flywheel inside that cover is not. You will require Laverda's puller (61818034), once you have undone and removed the left-hand threaded nut and washer. You will have to lock the crankshaft to do this.

With the engine in the frame, put the machine into 5th gear and lock the back brake. With the engine out of the frame lock the crankshaft using methods already described in the Engine section. The magneto flywheel is then easily pulled off holding the puller with one spanner and pulling it out with another. On early machines a spring sits behind the flywheel. Once off you will see the stator plate on which are five coils. Three of those coils are part of the generating system. First dismiss the two black (CDI) or silver (BTZ) coils which are the trigger mechanism for the Triple's ignition system. The two top horizontal coils comprise an inner (lighting) and an outer (charging), and the bottom horizontal coil is another charging coil. (See the wiring diagram).

These three coils are replaceable invidually. An auto-electrician should be able to assess their regular function without difficulty. Each coil is fixed by two screws. The stator plate is again easily removed once you have disconnected the wiring at the junction box under the tank. (Now read the Ignition section). This inner alternator cover now has an air flow hole. Early models did not feature this cooling hole at all, or its later mesh protecting grill. It makes good sense to retrofit one both to aid coil cooling and stop bits of grit entering. Also the wiring from the stator plate is held into the crankcase by a rubberised distance piece which should only fit one way around. If it is incorrectly fitted, it may cut the wiring. The alternator generating system has been dismissed in this short section because it is so simple. It either works or it doesn't. There is nothing to fiddle with and you must accept that it will not always recharge the battery! Check the ignition advance if you have removed the stator plate.

The Triple's alternator breather protective grille Don't Use the special tool to extract the flywheel magneto be without it - stones will grind away in there cover

Pics Magneto The Right Way Replace

It is important to replace this rubber plug the right way around. Otherwise when you replace the alternator cover it will slice through the wiring

When replacing the coil plate onto the crankcase, it is important to align both marks indicated here

The Triple's alternator breather protective grille Don't Use the special tool to extract the flywheel magneto be without it - stones will grind away in there cover

It is important to replace this rubber plug the right way around. Otherwise when you replace the alternator cover it will slice through the wiring

When replacing the coil plate onto the crankcase, it is important to align both marks indicated here

Starter motor

As all the machines being discussed in this guide are not equipped with a kick starter you should be able to assume that the starter motor fitted is reliable — and you can. Nippon Denso and Bosch starter motors are simple, robust and ultra reliable if they are subject to the normal maintenance procedures, and not filled with water from a hose pipe being used to wash the machine!

The starter drive chain is endless and must be placed onto the engine as shown (Twin)

The special tool for extracting the starter freewheel is in place (Twin)

This is a 1972 Twin and shows the machine s starter relay. Later machines did not have this relay placed behind this side cover nor the longitudinal battery and no air filter

The starter gear freewheel must align on that spline (Twin)

The special tool for extracting the starter freewheel is in place (Twin)

This is a 1972 Twin and shows the machine s starter relay. Later machines did not have this relay placed behind this side cover nor the longitudinal battery and no air filter

Twin (Nippon DensoJ

It is a Nippon Denso 0.95 hp motor. In order for sufficient torque to be transmitted to the engine to 'turn it over', there is a two stage reduction between starter and crankshaft. A 4.76:1 primary reduction takes place at the end of, but inside, the starter motor pinion by a planetary reduction system. A 2.42:1 secondary reduction is obtained by means of sprockets and a chain. The engine is then revolved by means of a freewheel with 3 or 6 pegs which engage in a driving pulley on the crankshaft (the same pulley as the dynamo drive).

To remove just the starter motor, remove the dynamo cover. Undo the connection on the end of the starter having disconnected both terminals of the battery. Remove the two bolts which fix the starter to the crankcase. A box spanner works best for the 'top" one (it has a nut inside the dynamo cover) which is got at from the dipstick side of the engine. The other bolt is fed in from the opposite direction and is normally hidden from view by the dynamo cover (it ISN'T the other bolt at the 'bottom' of the starter visible from the dipstick side of the engine). Remove the dipstick and place a piece of rag in the orifice. With a pair of circlip pliers remove the circlip which fixes the small gear to the starter pinion. Now carefully tap (with a hide-headed hammer) the starter gear on its pinion, holding the body of the starter motor level on the left hand side of the engine. Remove the starter body and retain the gear wheel and drive chain. You can now remove the chain.

The starter gear freewheel must align on that spline (Twin)

The starter drive chain is endless and must be placed onto the engine as shown (Twin)

If you are certain the starter motor is faulty you can go through similar checks to those described for the Twin's dynamo.

The starter comes apart in a similar way to the dynamo. Check the brushes — their original length is.16.7mm and they should be replaced when they are less than 10.0mm. If you can measure it, their spring pressure should be 800-900 grams (about 2 pounds). The commutator can be cleaned as well. Refitment of the starter is a straightforward reverse sequence. For starter freewheel removal see the Maintenance section.

A starter relay is fitted to enable enough current to be switched to the starter. It is located on the left hand side of the machine, behind the side panel, and next to the fuse box. It takes a lot of power to work the starter — a minimum of 7.5 volts. This means that the relay should emit a loud clack every time the starter button is pressed. If this does not happen, then by-pass the relay and check whether the starter then works. If it does, then the relay or its wiring is faulty. The contacts in the relay sometimes get wet and dirty — clean them with some light emery cloth. If this is not possible, replace the relay. If the starter still does not turn, then go back and check the contacts of the starter button on the handlebars. Finally if all this then points to a faulty starter, remove the starter and check it through.

NOTE: It has been known for starter motors to fill up with water if the machine has been used or left in heavy rain or in a flood. There is a drain hole in the crankcase allowing water to empty from the 'shelf' in which the starter sits. Make sure its not blocked.

Triple (Bosch)

The Triple uses a similar starter to the Twin although obviously it does have detail differences. Its removal is in fact much less complicated. First disconnect the cable to the starter once you have disconnected the battery. Undo the top alien screw, which is the one closest to the barrel, from the left hand side of the engine. (It requires a very long alien key). Undo and remove the other bolt from the right hand side of the engine. This bolt is not covered by any side cover. Carefully withdraw the starter body. Its drive is geared and therefore it should pull away easily. A gasket is fitted. The starter freewheel's removal is described in the Ignition section because it is necessary to remove the magneto flywheel and starter plate to get at it. Also it requires no maintenance as does the freewheel fitted to the Twin.

The CDI-equipped Triple's relay sits at the tail of the fuel tank and can be got at by lifting the seat. The BTZ-equipped sits between the battery and air filter box.

All further maintenance tasks for the starter and relay are similar to those of the Twin.

Ignition system - Twin (except late SFC)

General maintenance tasks have been described in the Maintenance section — they include contact points changing and setting and ignition timing. This section will discuss further dismantling and the other components, such as the coils. Spark plugs — much has been said about spark plugs previously but it is worth re-stating that correct fitment is essential. Champion N2 is the answer. It is possible to use Bosch W25QT2 on the low compression Twins and NGK B9EV in them all but the very high compression S and SFCs. All the plugs are very COLD and must be used. DO NOT let yourself be talked into other equivalents to get you out of trouble'. They won't — they'll get you into it. If your machine is properly tuned you should have no trouble with fouling up except under really long term town usage. All engines, no matter what state of tune, are designed to be revved. Always graphite grease the threads and use new washers. Torque the plugs to 20 ft.lb. The thread type, if recutting is necessary, is 14 x 1.25mm.

★ Plug caps and leads — the caps and leads which are fitted by the factory are the best ones to use. There is no advantage to change them to another sort. Never use the nipple on the top of the plugs but always use the smaller rubber collar which is fitted inside the cap. The metal cover over the cap is simply that — it clips over a plastic cap and provides it with protection. The plug leads are continuous metal strands and screw into the plug cap. Don't change them for anything which is 'super' suppressed. Make sure the leads are always clean, intact and not kinked; also that they are guided around the frame to the coils, and pushed into them, properly. If you replace caps and leads, always do so in pairs.

★ Coils — Super Bosch coils are used and they are superb, being tough and super reliable. They are clamped up to the top frame tubes under the centre of the tank. It is essential that they are mounted lust so' for there is so little room to move. Juggle them both and juggle their two fixing methods — sliding clamp around their body and that clamp to the frame. Make sure that their contacts are tight but not jammed on. These spade tag contacts are liable to fracture and lose contact if everything is not just so. The wiring loom is very tight as is the angle through which the wiring and coils have to turn. The coils get hot as they work. Do not leave the ignition switch on without the engine running. Do not cover the coils with rags or any other protective material but do make sure the rubber contact covers are fitted and that they are sprayed with an inhibitor such as Damp Start or WD40.

Other manufacturer's coils will work but the Bosch ones fitted are the best. Current intensity should be 1.3 amps. Resistance of the primary winding should be 3.6 to 4.1 ohms and may be determined by an ohmeter. Disconnect the terminals from the current circuit and test the primary terminals.

★ Ignition switch — several types of ignition switch have been used, the earliest 'in the headlamp' variety being the most unreliable. The later Nippon Denso type are quite reliable. There is little that can be done with the early 'big key' headlamp switched other than disassembling them and sorting out all the contacts. Apparently the contacts become fragile and eventually don't work. Perhaps the only real solution, if bending the tabs to contact again fails, is to ignore that switch and fit another elsewhere. Replacement or repair is not possible.

The ND type is a reliable yet sealed unit which is fixed to the instrument panel in the orifice through which the clutch/brake cables used to pass, by a special threaded ring. Its removal is straightforward. (Earlier switches are similar). Repair work is not possible. A little spray of WD40 helps it. Key numbers are stamped on it. The later key position makes it easy to jingle your keys around on the instrument panel taking the paint off with them. Avoid this by making a special key tie. New keys are available.

★ Condensers — two condensers are fitted to the contact plate. The originals are riveted onto the ignition plate. Their replacement is therefore difficult in that you have to drill out the rivets. If you can rivet back a new one, all well and good, but perhaps the easiest way is to use a tiny nut and bolt. Never replace a condensor without taking off the ignition plate. There is no way of actually testing a condensor. If you are certain that is what has failed, then replace it and check again. Burned contact breakers are often indicative of faulty coildensors.

★ Ignition Plate — as described in the Maintenance section, the ignition plate is, in fact, two plates one behind the other with a set of contact points fitted to each. The ignition plate has to be removed if you are to get at the primary drive and advance and retard mechanism. Remove the contact points cover and then remove the wiring from the two contact points connections. Now undo the three screws which fix the ignition plate complete to the casing. Now carefully pull off the ignition plate holding the contact points away from the rotor. Be careful. Behind the ignition plate, sits the advance/retard mechanism. This is fixed to the inner plate by two small screws. Remove these and then pull out the mechanism. It is now possible for the inner plate to be removed by undoing its central fixing bolt, but first lock the crankshaft (put the machine into 5th gear and hold the rear brake firmly on). (Use the Laverda special tool (61818976) to extract the plate only if you are not removing the primary cover. It's unwise to use any other means). Now you can release the primary drive cover — it'll remove the inner plate too — and release the oil pump, etc.

An overhead shot of the Twin's two ignition coils in position

Replacement is straightforward, but be careful with the placing of the inner plate and contact points and their wiring. The inner plate fits onto a removable key on its shaft. Do not forget to inspect the oil seal through which the inner plate rotates. If it is worn, replace it and grease the inner plate shaft lightly. When replacing the advance/retard mechanism align its cutaway with the key held by the inner plate.

NOTE: In due time the advance/retard springs wear out. No spare parts are listed separately therefore you will have to buy the mechanism complete. As this comes with the rotor as well, it's perhaps no bad thing.

Always retime the ignition timing and reset the contact breaker points. Never be tough with the fixing screws of the ignition plate — they will break.

Ignition timing using a stroboscope

As the standard method for ignition timing is so good on the Twin (given in the Maintenance section) the above is not described here in anything other than outline. The main benefit is that it can be used to check the proper working of the advance/retard mechanism. Set the ignition timing and adjust the contact points. Connect the three cables of the strobe to the correct terminals of the battery (check polarity) and to the right hand cylinder (plug lead — do not remove the cap).

Remove the dynamo cover. Start the engine and allow it to tickover at 800 -1000 rev/min. Hold the lamp near the timing mark on the right hand side of the crankcase. 'PM' on the crankshaft pulley should 'align' with the mark on the crankcase. If 'PM' appears earlier (to the left of), the timing is too far advanced — if to the right or after, it's too retarded. If its not correct, stop and set the timing as described in the Maintenance section. Do the same test for the left hand cylinder.

Start the test again for the right hand cylinder and as the engine is revved the 'PM' mark should progressively travel anti-clockwise. At between 2800 - 3100 rev/min mark 'A' should align with the mark on the crankcase. If the marks. A" and that on the crankcase, remain unstable, or stable only beyond 3100 rev/min, then the auto advance mechanism is seized. It should be removed and cleaned. If the static timing is correct and pre-ignition or pinking is heard as the engine speeds up then the auto advance is working prematurely. This will mean worn or the wrong springs.

Auto advance operates as follows: Degrees on the crankshaft 0 Rev/min 850-1000

10 1200-1550

20 1680-2050

30 2200-2650

40 2800-3100

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