There is a wide choice of gearboxes available for all series 1, 2 and three machines. The trouble is with Lambretta is that of course they have stopped production which means finding your choice of gearbox has become harder and more expensive. The two or three main gearboxes for good all round performance in particular are commanding high prices, so to achieve gear changes for performance conversions, rather then change complete gearboxes, you can change the front and or rear sprocket to raise or lower gearing.

Depending on the level of tune, exhaust used or type of performance you require, i.e touring or round town, final drive ratios can be between 4.6 and 5.3

The most common way to adjust the way your gearbox works by lowering or raising the ratios by means of fitting different front or rear sprockets.

Front sprockets.
These raise the gearing the more number of teeth it has, and it quite a high percentage. Sizes available are :-
14T** 15, 16, 17, 18, 19, 20, 21.
** (we would recommend having a 14T machined with the front colett other wise the sprocket can spin round.)

Rear sprockets
These lower the gearing the more number of teeth it has, but in lower percentage then the front. :-
44, 45, 46, 47, 48, 49, 50.

By choosing different gearboxes and or the large number of variation on sprockets, you can alter your ratios to suit you and the conditions you use your scooter, as well as power made. It does'nt always equate that bolting on a performance kits will need the raito to be raised to gain more speed. In fact the opposite can be found in sme cases, in that lowering your gearing will give you more top speed in certain circumstances. For example a scooter with a bolt on kit and expansions made to rev harder, may well require lower gearing in order to rev out in top gear. The extra speed will come from the engine revving harder. If the gearing is to tall, the scooter may well not rev as hard, thus a lower top speed is seen. On scooters with a lower revving kit / exhaust combination, higher gearing can be used as the scooter will make its power lower down, and probably will not be cable of "reving out" to to the restriction of how it works. In this case the higher top speed is gained by the torque of the set up.

The trouble with fitting different sprockets is then finding a chain that will fit the combination used can be tricky. Where we have quoted a upside down chain tensioner & chain, this is a worn chain that normally would be to large to use on standard set ups due to it being to long for tensioner adjustment. Genuine Innocenti chains are actually very good quality, so as long as all links look secure, all rollers have no damage, it is more then likely quite safe to use. Beware of new pattern chains on the market, some are not very good quality at all, ask your supplier for more details.

All gearboxes between series three Lambretta machines are interchangeable, they should really be changed as complete units though, even in most cases down to the end plate that holds them in place. You cannot unfortunately change one gear at a time (except in some rare cases), i.e. if you want a higher forth gear you cannot just take that from a different set up to gain more speed. Even though many gears may share the same number of teeth, they (again rarely) are not interchangeable one at a time, for example a GT 2nd gear has the same amount of teeth as the SX150 3rd gear, but the actual gears are not the same.

In the tables below you will find listed gearboxes as per each machine, these are as would have been fitted to the scooter leaving the Innocenti factory. Many racers and tuners swap gearboxes with modified machines to gain the best from their set ups, and it is fair to say unless you have modified you machine is some big way, you will gain nothing from changing the gearbox to a different type. There are some exceptions to this last statement, but it all depends on your individual machine.

For you to want to change the ratio, you would have had to have some sort of conversion to your machine, i.e. not just a new carb, racy exhaust and a bit of a tune. Capacity changes (i.e. 125 to 150cc) Imola and TS1 conversions (amongst the two more popular ones) and the fitting of a side car would probably be the main reasons for changing gearboxes. Even then it is not absolutely necessary to change the whole gearbox itself, many different overall ratios can be affected by simply changing the front or rear sprockets, again it depends on your machine and the reason for the need to change.

OK in the explanations below you will see the primary drive listed, this is your front and rear sprocket, the smaller the front the larger number the rear. The four (in most case) gears and ratios are then inside tables, the group teeth is some times refereed to as the cluster or Xmas tree.

If you want to work out any ratios for yourself, the equation is (Loose Gear Divided By Gear Cluster) x (Rear Sprocket divided by Front Sprocket)

Li 125 S1, S2, Early S3
(Italian & Spanish)
Gear Loose Gear Gear Cluster Standard Sprocket Information Changing the front and or rear sprockets to the following sizes will give the ratios below
15 - 46 16 - 46 17 - 46 18 - 46 19 - 46 20 - 46 15 - 47 16 - 47 17 - 47 18 - 47 19 - 47 20 - 47
Not really the best gearboxes to use for tuned engines, although as a last resort can be used with 18/47 to give similar set up to SX200, ie touring. 1st 51 9 17.37 16.29 15.33 14.48 13.72 13.03 17.75 16.64 15.66 14.79 14.01 13.32
2nd 42 12 10.73 10.06 9.47 8.94 8.47 8.05 10.97 10.28 9.67 9.14 8.66 8.23
3rd 39 16 7.47 7.01 6.59 6.23 5.9 5.61 7.64 7.16 6.74 6.36 6.03 5.73
4th 35 19 5.65 5.3 4.99 4.71 4.46 4.24 5.77 5.41 5.09 4.81 4.56 4.33
Chain (U= upside down chain guide required) 80 81U 81 82U 82 83U 81U 81 82U 82 83U 83
Estimated top speed (using 3.50*10 tyre) 5000rpm 45mph 48mph 51mph 54mph 57mph 60mph 44mph 47mph 49mph 52mph 55mph 58mph
6000rpm 54mph 57mph 61mph 64mph 68mph 72mph 52mph 56mph 59mph 63mph 67mph 70mph
7000rpm 63mph 67mph 71mph 75mph 79mph 84mph 61mph 65mph 69mph 74mph 78mph 82mph
8000rpm 72mph 76mph 81mph 86mph 91mph 96mph 70mph 75mph 79mph 84mph 89mph 94mph
9000rpm 81mph 86mph 91mph 97mph 102mph 108mph 79mph 84mph 89mph 95mph 100mph 105mph


GP125 and Li125 special gearbox
GP200 with 18/47
Gear Loose Gear Gear Cluster Standard Sprocket Information Changing the front and or rear sprockets to the following sizes will give the ratios below
15 - 46 16 - 46 17 - 46 18 - 46 19 - 46 20 - 46 15 - 47 16 - 47 17 - 47 18 - 47 19 - 47 20 - 47
Li 125 Special and GP125 are the same gearbox as the GP200, just with different sprockets. In GP200 spec it is a suitable for any standard or tuned motor with good results. 1st 50 10 15.33 14.38 13.53 12.78 12.11 11.5 15.67 14.69 13.82 13.05 12.37 11.75
2nd 42 12 10.73 10.06 9.47 8.94 8.47 8.05 10.97 10.28 9.67 9.14 8.66 8.23
3rd 39 15 7.97 7.48 7.04 6.64 6.29 5.98 8.15 7.64 7.19 6.79 6.43 6.11
4th 36 18 6.13 5.75 5.41 5.11 4.84 4.6 6.27 5.87 5.53 5.22 4.95 4.7
Chain (U= upside down chain guide required) 80 81U 81 82U 82 83U 81U 81 82U 82 83U 83
Estimated top speed (using 3.50*10 tyre) 5000rpm 41mph 44mph 47mph 50mph 52mph 55mph 40mph 43mph 46mph 48mph 51mph 54mph
6000rpm 50mph 53mph 56mph 60mph 63mph 66mph 48mph 52mph 55mph 48mph 61mph 65mph
7000rpm 58mph 62mph 66mph 70mph 73mph 77mph 57mph 60mph 64mph 68mph 72mph 76mph
8000rpm 66mph 71mph 75mph 80mph 84mph 88mph 65mph 69mph 73mph 78mph 82mph 87mph
9000rpm 75mph 80mph 85mph 90mph 95mph 100mph 73mph 78mph 83mph 88mph 93mph 97mph


Li 150 (Italian & Early
Spanish Models)
Gear Loose Gear Gear Cluster Standard Sprocket Information Changing the front and or rear sprockets to the following sizes will give the ratios below
15 - 46 16 - 46 17 - 46 18 - 46 19 - 46 20 - 46 15 - 47 16 - 47 17 - 47 18 - 47 19 - 47 20 - 47
Generally the preferred choice of gearbox for most tuned machines. 1st 50 11 13.93 13.07 12.30 11.61 11.0 10.45 14.24 13.35 12.56 11.86 11.24 10.68
2nd 41 14 8.98 8.42 7.92 7.48 7.09 6.73 9.17 8.6 8.09 7.64 7.24 6.88
3rd 37 17 6.67 6.26 5.89 5.56 5.27 5.0 6.82 6.39 6.01 5.68 5.38 5.11
4th 34 20 5.21 4.89 4.6 4.34 4.12 3.91 5.33 4.99 4.7 4.44 4.2 4.0
Chain (U= upside down chain guide required) 80 81U 81 82U 82 83U 81U 81 82U 82 83U 83
Estimated top speed (using 3.50*10 tyre) 5000rpm 49mph 52mph 55mph 58mph 62mph 65mph 48mph 51mph 54mph 57mph 60mph 64mph
6000rpm 58mph 63mph 66mph 70mph 74mph 78mph 57mph 61mph 65mph 69mph 72mph 76mph
7000rpm 68mph 73mph 77mph 82mph 86mph 91mph 67mph 71mph 76mph 80mph 85mph 89mph
8000rpm 78mph 83mph 88mph 94mph 99mph 104mph 76mph 81mph 87mph 92mph 97mph 102mph
9000rpm 88mph 94mph 100mph 105mph 111mph 117mph 86mph 92mph 97mph 103mph 109mph 115mph


GP150, SX150 and Li150 special gearbox Gear Loose Gear Gear Cluster Standard Sprocket Information Changing the front and or rear sprockets to the following sizes will give the ratios below
15 - 46 16 - 46 17 - 46 18 - 46 19 - 46 20 - 46 15 - 47 16 - 47 17 - 47 18 - 47 19 - 47 20 - 47
Probably one of the worst gearboxes you can use in a tuned motor due to the big gap between third and forth 1st 50 10 15.33 14.38 13.53 12.78 12.11 11.5 15.67 14.69 13.82 13.05 12.37 11.75
2nd 42 12 10.73 10.06 9.47 8.94 8.47 8.05 10.97 10.28 9.67 9.14 8.66 8.23
3rd 39 15 7.97 7.48 7.04 6.64 6.29 5.98 8.15 7.64 7.19 6.79 6.43 6.11
4th 35 19 5.65 5.3 4.99 4.71 4.46 4.24 5.77 5.41 5.09 4.81 4.56 4.33
Chain (U= upside down chain guide required) 80 81U 81 82U 82 83U 81U 81 82U 82 83U 83
Estimated top speed (using 3.50*10 tyre) 5000rpm 45mph 48mph 51mph 54mph 57mph 60mph 44mph 47mph 50mph 53mph 56mph 59mph
6000rpm 54mph 57mph 61mph 65mph 68mph 72mph 53mph 56mph 60mph 63mph 67mph 70mph
7000rpm 63mph 67mph 71mph 76mph 80mph 84mph 62mph 66mph 70mph 74mph 78mph 82mph
8000rpm 72mph 77mph 82mph 86mph 91mph 96mph 70mph 75mph 80mph 85mph 89mph 94mph
9000rpm 81mph 86mph 92mph 97mph 103mph 108mph 79mph 85mph 90mph 95mph 101mph 106mph


Li 150 Special 'Pacemaker'
Late Li125 Italian
(Frame No. >94018)
Gear Loose Gear Gear Cluster Standard Sprocket Information Changing the front and or rear sprockets to the following sizes will give the ratios below
15 - 46 16 - 46 17 - 46 18 - 46 19 - 46 20 - 46 15 - 47 16 - 47 17 - 47 18 - 47 19 - 47 20 - 47
Good gear box, although Pacemaker can have a weak third gear when used hard, generally this is the best to use. They have become very hard to find, so the use of the Li150 is the next best. 1st 50 11 13.93 13.07 12.30 11.61 11.0 10.45 14.24 13.35 12.56 11.86 11.24 10.68
2nd 41 13 9.67 9.07 8.53 8.06 7.63 7.25 9.88 9.26 8.71 8.23 7.8 7.41
3rd 39 17 7.03 6.6 6.21 5.86 5.55 5.28 7.19 6.74 6.34 5.99 5.67 5.39
4th 35 19 5.65 5.3 4.99 4.71 4.46 4.24 5.77 5.41 5.09 4.81 4.56 4.33
Chain (U= upside down chain guide required) 80 81U 81 82U 82 83U 81U 81 82U 82 83U 83
Approximate top speed (using 3.50*10 tyre) 5000rpm 45mph 48mph 51mph 54mph 57mph 60mph 44mph 47mph 50mph 53mph 56mph 59mph
6000rpm 54mph 57mph 61mph 65mph 68mph 72mph 53mph 57mph 60mph 63mph 67mph 70mph
7000rpm 63mph 66mph 71mph 76mph 79mph 84mph 62mph 66mph 70mph 74mph 78mph 82mph
8000rpm 72mph 77mph 82mph 86mph 91mph 96mph 70mph 75mph 80mph 85mph 89mph 94mph
9000rpm 81mph 85mph 92mph 97mph 103mph 108mph 79mph 85mph 90mph 95mph 101mph 106mph


TV175, SX200 Gear Loose Gear Gear Cluster Standard Sprocket Information Changing the front and or rear sprockets to the following sizes will give the ratios below
15 - 46 16 - 46 17 - 46 18 - 46 19 - 46 20 - 46 15 - 47 16 - 47 17 - 47 18 - 47 19 - 47 20 - 47
Quite tall for most engines, using 14/47 sprockets improves this no end. Good touring gearbox if your motor can produce the torque. 1st 49 12 12.52 11.74 11.05 10.43 9.88 9.39 12.79 11.99 11.29 10.66 10.1 9.6
2nd 40 14 8.76 8.21 7.73 7.3 6.92 6.57 8.95 8.39 7.9 7.46 7.07 6.71
3rd 37 18 6.3 5.91 5.56 5.25 4.98 4.73 6.44 6.04 5.68 5.36 5.08 4.83
4th 33 21 4.82 4.52 4.25 4.01 3.8 3.61 4.92 4.61 4.34 4.10 3.89 3.69
Chain (U= upside down chain guide required) 80 81U 81 82U 82 83U 81U 81 82U 82 83U 83
Estimated top speed (using 3.50*10 tyre) 5000rpm 53mph 56mph 60mph 63mph 67mph 70mph 51mph 55mph 58mph 62mph 65mph 69mph
6000rpm 63mph 67mph 72mph 76mph 80mph 84mph 62mph 66mph 70mph 74mph 79mph 83mph
7000rpm 74mph 79mph 84mph 89mph 94mph 99mph 72mph 77mph 82mph 87mph 92mph 97mph
8000rpm 84mph 90mph 96mph 101mph 107mph 113mph 83mph 88mph 94mph 99mph 105mph 110mph
9000rpm 95mph 101mph 108mph 114mph 121mph 127mph 93mph 99mph 106mph 112mph 118mph 124mph


TV200 Gear Loose Gear Gear Cluster Standard Sprocket Information Changing the front and or rear sprockets to the following sizes will give the ratios below
15 - 46 16 - 46 17 - 46 18 - 46 19 - 46 20 - 46 15 - 47 16 - 47 17 - 47 18 - 47 19 - 47 20 - 47
If your engine can make enough torque to pull this tall gearing, the TV200 has a great even spread of gear ratios. 1st 47 13 9.7 9.1 8.56 8.09 7.66 7.28 9.92 9.3 8.75 8.26 7.83 7.44
2nd 39 15 7.97 7.48 7.04 6.64 6.29 5.98 8.15 7.64 7.19 6.79 6.43 6.11
3rd 36 19 5.81 5.45 5.13 4.84 4.59 4.36 5.94 5.57 5.24 4.95 4.69 4.35
4th 32 22 4.46 4.18 3.94 3.72 3.52 3.35 4.56 4.27 4.02 3.8 3.6 3.42
Chain (U= upside down chain guide required) 80 81U 81 82U 82 83U 81U 81 82U 82 83U 83
Estimated top speed (using 3.50*10 tyre) 5000rpm 57mph 61mph 65mph 68mph 72mph 76mph 56mph 60mph 63mph 67mph 71mph 75mph
6000rpm 68mph 73mph 78mph 82mph 87mph 91mph 67mph 72mph 76mph 81mph 85mph 90mph
7000rpm 80mph 85mph 91mph 96mph 101mph 107mph 78mph 84mph 89mph 94mph 99mph 105mph
8000rpm 91mph 98mph 104mph 110mph 116mph 122mph 90mph 96mph 102mph 108mph 114mph 120mph
9000rpm 103mph 110mph 117mph 124mph 131mph 137mph 101mph 108mph 114mph 121mph 128mph 135mph


GP200 Late Indian Gear Loose Gear Gear Cluster Standard Sprocket Information Changing the front and or rear sprockets to the following sizes will give the ratios below
15 - 46 16 - 46 17 - 46 18 - 46 19 - 46 20 - 46 15 - 47 16 - 47 17 - 47 18 - 47 19 - 47 20 - 47
If your after a new gearbox, the Indian ones are one of the few still made, but even genuine ones are in short supply. 1st 50 10 15.33 14.38 13.53 12.78 12.11 11.5 15.67 14.69 13.82 13.05 12.37 11.75
2nd 42 12 10.73 10.06 9.47 8.94 8.47 8.05 10.97 10.28 9.67 9.14 8.66 8.23
3rd 38 16 7.28 6.83 6.43 6.07 5.75 5.46 7.44 6.98 6.56 6.2 5.87 5.58
4th 36 18 6.13 5.75 5.41 5.11 4.84 4.6 6.27 5.87 5.53 5.22 4.95 4.7
Chain (U= upside down chain guide required) 80 81U 81 82U 82 83U 81U 81 82U 82 83U 83
Estimated top speed (using 3.50*10 tyre) 5000rpm 41mph 44mph 47mph 50mph 52mph 55mph 40mph 43mph 46mph 48mph 51mph 54mph
6000rpm 50mph 53mph 56mph 60mph 63mph 66mph 48mph 52mph 55mph 58mph 62mph 65mph
7000rpm 58mph 62mph 66mph 70mph 73mph 77mph 57mph 60mph 64mph 68mph 72mph 76mph
8000rpm 66mph 71mph 75mph 80mph 84mph 88mph 65mph 69mph 73mph 78mph 82mph 87mph
9000rpm 75mph 80mph 85mph 90mph 95mph 100mph 73mph 78mph 83mph 88mph 93mph 97mph