Performance Upgrades

It’s important to remember that these vehicles have three wheels and were a redesigned motorcycle meant to do a maximum of 40mph, not really the ideal model for high speed and race engines. That said, it is human nature to tinker and because they are so much like Lambretta scooters, the ever growing number of followers will undoubtably start modifying them out of all recognition.

It is possible to upgrade Lambro engines using Lambretta tuning parts. For all 175 Lambros it is worth getting a 200cc barrel for extra power on hills. The later FLi’s and all 175cc’s thereafter have big block stud spacing so a 200cc barrel will go straight on. For the small block Fli’s a Mugello kit or similar will do the job. My Fli has a Lambro 200cc barrel, SH1/20 carb upgrade, MEC crank and electronic ignition. It will do 45 on the flat (on the GPS) and nearly 50 downhill which as fast I ever want to go in it! It is pretty scary at that speed on 8 inch wheels and drum brakes but goes well round town and keeps up with the traffic too.

Please bear in mind that the magneto housings on XX Lambros are all exactly the same as Li/SX/TV Lambrettas. GP cranks will not fit unless you change the mag housing as well. SQUARE CABS? All carburettors, exhausts, cranks, bearings and top end conversions can be used. TS1 kits seem to be the favourite on conversions so far, possibly because the carburettor mounts in right direction which is obviously wrong for Lambrettas but perfect for the Lambros. Lambretta ‘small block’ conversions will work fine on the Lambro small block engines too. A Lambretta 5 plate clutch as will strengthened Lambretta springs. Readspeed have built a six plate clutch for the Lambros. Please contact them for details.

Tuning a Lambro has a few hurdles that need to be overcome and I will try and give you the benefit of what I have learned (by trial and error).

The ignition

The kickstart models can be modified using a standard Indian electronic ignition from a Lambretta, which is tried and tested. The magneto housing is the same as the SX/TV/Li Lambrettas. Obviously don’t buy one of the rubbish Indian imports, buy one from a reputable dealer that has been properly rewired and had decent components fitted.

In order to charge the battery, a 12V DC regulator from a Vespa with the extra contact will provide an extra output wire which can used to charge the battery and works well particularly if you run the lights on the output from the electronic stator and everything else from the battery. You will also need to change the ignition switch. I recommend using a DC Casa Lambretta one, they are great quality and look good. They can be obtained from Scootopia in Weston Super Mare.

When I converted my Lambro 175 I used the Italian GP200 wiring diagram as a guide. The wiring colour codes are pretty much exactly the same as a Lambretta with white/black and green/black used for the indicator system. It is very straight forward to do if you keep in mind that it is the same as a GP and use the Lambro wiring diagrams from this link as a guide to any other conundrums you might have.

With the electric start models there are added complications. The flywheel is radically different to the standard Lambro/Lambretta ones and the stator plate is very small. The points system works ok but isn’t the most reliable setup and for tuned engines leaves something to be desired. At the time of writing Jerome from Readspeed has just converted their race electronic ignition to work with the electric start Lambros incorporating the original Dynostarter (click here for a demo of their awesome TS1 conversion c/w race electronic ignition system). It works a treat but you will need to dig deep for one of these beauties.

The other option is to remove the electric starter and use a kickstart which solves the problem and you can use the Indian electronic setup. The other advantage of this is if you are going for more power the dynostarter will take power from the engine to turn it so getting rid of it could give you a couple more horsepower. If you are brave you could try a home brewed conversion but that would require better engineering skills than I can manage, good luck with that. Its probably not a good idea to use points if you do an upgrade though.

Gearing and differential

Lambros were geared to do between 35 and 40mph which by modern standards is pretty poor. I went to Weston and the Isle of Wight in my Lambro 175 last year (from the Midlands) and an extra 10-20mph on runs like that would be very helpful. It managed to do about 47mph flat out and cruised at about 43mph (which still beat some of the Lambretta riders!).

The gearing information for various models can be found on the models pages. Some of the later Lambros have slightly different gear ratios so you could possibly increase the top speed of a Lambro 175 by using a 550N gear set (I haven’t tried it yet). Gear clusters from Lambrettas do fit but the ratios (I’m informed) are so high that the Lambro probably wouldn’t even set off. I have to admit that I haven’t done much experimentation with this so I’m relying on information from reputable sources. If anyone has experimented with this we would be glad to hear from you about your endeavours.

It seems the best place to increase the gearing for a tuned motor is the differential. The diffs on the Fli’s are much smaller than the later Lambro’s so the components will not fit. It seems that it wouldn’t be too much of a problem to get a Reliant axle to fit on the later Lambro models. At the time of writing I haven’t had the opportunity to check which diffs have higher ratios and which fit in which axles. I will put the results up here when I get the opportunity to do some tests.

From the Lambro 200 onwards 10 inch wheels were introduced. Tubeless tyres will fit on these rims and old style Mini 10” tyres work perfectly. As they are bigger than the standard 4.50x10 tyres they may also increase the gearing slightly and grip a lot better. I wouldn’t advise using Mini tyres on the front though, it makes the steering too heavy to use.

Drive shafts

The weak point for tuning Lambros is the drive shafts, especially if you have a Lambro 175 or previous models and as time goes by, replacement ones are getting harder to find. Fli half shafts are only 12mm thick and will not stand much more than 10HP. My Fli is probably about 12 horsepower and has already snapped a driveshaft in its first thousand miles resulting in complete axle rebuild. The later Lambro half shafts are much more industrial but still suffer from failure when the torque is cranked up.  A quick search on the internet will reveal a TS1 Lambro in California and the story of broken driveshafts.

 

Other than these few problems tuning Lambros is loads of fun. The interest in them seems to doubling year by year and as time passes I expect people will find innovative solutions to the problems listed above, perhaps some will even begin to produce aftermarket differential components so it is easier to alter the gearing. Good Luck and let us know how you get on!