EDITION 173 - AUGUST 2000
I think it's fair to say that the AF Rayspeed TS1 kit revolutionised the use of 200cc Lambrettas as rally machines. Here - at last - was a machine you could ride at high speed without one hand hovering over the clutch like a Wild West gunfighter guarding his 'piece' in a bar-room brawl. The nicasil-lined alloy cylinder dissipates heat so much more effectively than cast iron, that heat seizures should be virtually impossible to achieve. You can - of course - still seize a TS1. but your engine needs to be spectacularly out of tune in terms of ignition timing or carb jetting. Let's move on shall we..
The problem with the TS1 revolution is that it has always been restricted to the 200cc engine format, thus making the price of good Lambretta 200 engines rocket to frankly unrealistic levels.
The new Imola 186cc Lambretta cylinder kit threatens to not only bring an end to this stupid price situation for 200cc engine casings, but also to give the same new lease of life to the 125/150/175cc engine as the TS1 did for the larger motors.
In recent years these smaller capacity Lambrettas have flooded into the country from Italy. Sadly, owners wanting the 'cool' of a genuine 1960's scooter have often found themselves in a world of suspect reliability and frankly mundane performance - particularly if they were unfortunate enough to end up with a 125 LI.
Tino Sacchi - he of the buttock-bruising Model A touring articles - has been working on his Imola Kit for quite some time, but the recent Euro-Lambretta rally in Durham was the first time anyone in the UK has had a chance to see the results.
The demonstrator is based on an SX150, and is set up in the basic 'Imola' spec, which is a cylinder, piston, reedvalve and gasket set. A manifold is supplied which takes 28mm or 30mm PHB-series carbs. The kit is also available with a replica 'Ancillotti' style big-bore standard exhaust with it's own alloy exhaust manifold for easier removal.
The reedvalve cylinder is very much a copy of the TS1 in terms of layout, so the right-hand positioning of the carb requires removal of the battery tray from the frame. People who don't want to hack their chassis may want to wait for Richard Taylor's 175cc reed kit which is also soon to be in production, but utilises a carb in the conventional position.
The first thing I noticed about the Imola demonstrator was how well balanced the engine seemed. It took a little less effort to kickstart than my own TS1, but it only vibrated a quarter as much (sorry girls). In fact it seemed to shake less than a lot of standard Lambrettas I've ridden, which has to be good news in terms of how well bodywork, cowlings and exhausts will stay together.
The crankshaft in the demo machine ia s MECEUR design which has been digitally re-balanced to suit the kit; no doubt aiding the engine's smoothness considerably. The piston meanwhile is basically a 64mm diameter standard-type SX/GP piston with holes cut in the skirt for the reedvalve, and improved piston rings. While this spec of piston should be fine for most people - since it will mean bolting it on an engine fitted with an LI/SX/GP crank - Tino reckons the kit should work better-still with a longer 115mm TV175 type con rod, and the alternate piston which has it's gudgeon pin positioned nearer the piston crown.
Tino is currently getting a improved high performance pistons made for the kit by Asso, in both GP and TV versions. So far a couple of the engines using the standard-type pistons have completed several thousand kilometres without problem, but Tino wants to make a stronger piston available for those who intend to tune their Imola kits for more power.
In terms of performance, the standard demonstration version of the Imola (28 mm carb and Ancillotti pipe) produces 15.23 hp at the rear wheel. This is around what you'd expect from a Vespa T5 fitted with a bolt-on Malossi 172cc kit for istance. On the road, the performance comparison continues with approximately the same amount of go as a kitted T5. The main difference is that the Imola, with it's reed valve induction and remarkably crisp carburation, has more power at low revs than the rotary disc Vespa T5. The Lambretta's manners at low revs are impeccable, and just as suitable for town use as a standard engine.
Acceleration is brick if not quite TS1 league. Peak power is at a relatively high 7,950 rpm, but there is over 12 hp from 5,500 rpm right through to 8,500 rpm giving a broad useable power band.
The demo scooter was also fitted with a 5-speed gearbox based on the old Omega kit of the 1980s. These boxes were never renowned for their strength originally, but but Tino has re-made the 3rd gear cog, and it certainly appeared to work well enough. Given that the gear selector and gears all need to be thinner to select five ratios, Tino says that the box must be very carefully assembled with quality parts. Those with engines producing much over 20 hp, or intending to ride hard, are still best off avoiding a five speed conversion.
The five speed box suited the Imola very nicely though, since fourth gear provided a ratio with which to climb a long hill, but still holding a good speed and without revving the engine too hard. Change up to top gear and on the flat - with an upright rider possessing the same aerodynamic qualities as a block of flats - the speedo gradually built up to 120 Kmph (75 mph). At the speed the motor felt thoroughly content, and still very smooth.
Tino seemed to think that the standard Imola should be able to manage 130 Kmph (81 mph) on the flat and 140 Kmph (87 mph) downhill, lying flat, but we are still talking about figures supplied by a Lambretta speedo here, and therefore not strictly based in science.
What seemed certain is that a properly fitted Imola kit has the ability to transform a 125/150/175 Lambretta into a machine capable of sitting on the motorway at 65/70 mph, which is what most owners are looking for. The important phrase there was 'properly built', which means fitting a decent crank, bearings, oilseals and clutch. Those expecting to throw one of these kits onto their standard imported LI150 which has been dragged out of a shed in Italy (after sitting for 20 years and given the minimum of care to get it running) should really think twice. It would be a waste to blow up a new kit just because you tried to run it on a rusty LI crank from 1963.