Kit name: SIL – Stage 4
Manufacturer/Supplier: SIL/ Scooter Restorations/AF Rayspeed
RRP: £100-£140
Average estimated power output: 9bhp
Bore: 66mm
Stroke: 58mm
Capacity: 198cc
Induction type: Piston ported
Overview: The Stage 4 cylinder was manufactured by SIL and based around an old Stage 4 tune. Made from cast iron, this cylinder kit is cheap enough to get you going, and despite its low quality some units have been known to last years… presumably due to the very low power output they produce, thus not really stressing any major components. It' s a cheap starting g point, but when it comes to adding power, with various exhausts and big carbs etc., it's best also to look at additional remedial work to the cylinder
(as follows).
Tuning suggestions: When it comes to precision engineering, the dimensions of the cylinder fall somewhat below par. To get the ports cleaned up correctly requires a reasonable amount of work, and most ‘home tuners' should be at least capable of chamfering off the sharp and uneven edges. To progress the kit, we would recommend adjusting the port shapes and sizes, but this is best left to someone more knowledgeable, as it is easy to go too far and render the kit useless. Next step up the ladder would be to replace the basic piston which often accompanies these kits, for something of better quality, preferably with 1mm rings. This should be matched, ideally, with a cylinder re-bore. The bbenefitfit hhehere is that if startting with a 6666mm kit att 200cc, yyoou may aas well go straight up to 225cc with a 70mm piston, and a have th t he head machined to match. At this stage, you now have a pretty basic but decent set-up; the question is… was it all worth it, in terms of cost? If you already owned the kit, then yes. But otherwise, for the money spent, you'd be as well going straight in for a pre-packaged cylinder kit of some kind. Some tuners have managed to get good results (see our previous ‘Bang for Buck' series for Stage 4 tuning options) from this Stage 4 225cc set-up, many in excess of 20hp, which is not to be sniffed at. They can easily be matched with a decent Clubman and 25mm carb for those wanting original looks, or an expansion and big carb to give more fruity behaviour. If you want to have a go at home tuning, the cheap price of the cylinder means it is an affordable way to get started.
Manufacturer/Supplier: Ron Moss
RRP: £550
Year launched: 2011
Average estimated power output: 22bhp Bore: 70mm
Stroke: 58mm
Capacity: 223cc
Induction type: Piston ported
Overview: Launched by Ron Moss a decade ago now, this kit offers improved cooling qualities over standard items due to its larger fin area on both the cylinder and the oversized head. Unsurprisingly, the cylinder head itself became a roaring success in its own right and probably sold more units than the cylinder kit, as many engine builders used them on a variety of engines, other than just the Avanti. The TT3 also features a bridge exhaust port, allowing it to be much wider, the only disadvantage is it makes it slightly more complicated if you wish to tune it. Made from aluminium and Nicasil lined, it is a hard-wearing and lightweight kit, despite its larger size. The cylinder head is a centre squish design and has a larger diameter to aid cooling and requires a larger-sized head cowling which comes with the kit. This unit is aimed mainly, in its standard format, at the touring market and with its lower running temperature is ideal for long-distance use. The port timings tended to vary slightly on early kits, but on the whole, the port timings were kept low in order to maximise torque and let the kit pull good gearing in order to attain a decent top speed.
Tuning suggestions: The kit is piston ported so has plenty of scope when it comes to tuning it. Reed-valve conversions are quite common, although the back cylinder wall has a rather unique ‘wrap around' transfer/ boost port added in, which can make the reed-valve conversion less straightforward than on traditional piston-port kits which do not have this feature. One thing worth noting is that on most reed-valve kits which do have ‘rear wall' boost ports, these are angled steeply upwards (usually around 60°) in order to ‘flush' out the combusted gases from the cylinder head. However, on the
Avanti, the rear wall port angle flows rather more closely towards the exhaust port, so benefit can be had by re-angling the upward flow of this port where possible. As already mentioned, the unit has a bridged exhaust port, making it slightly more awkward in that area to work on, but when done right, and using a good expansion pipe, then 30bhp is easily achievable.
Manufacturer/Supplier: Lambretta.it/
Tino Sacchi
RRP: Circa €8500 depending on spec, exchange rate and import tariffs
Year launched: 2010
Average estimated power output: 24hp (early version) – 30hp (late version) Bore: 54mm (early)
Stroke: 54mm (early)
Capacity: 247cc (early version)/275 (late version)
Induction type: Piston ported (early)/ reed valve (late)
Overview: The Targa Twin 250 was Tino Sacchi's answer to finishing off the original twin-cylinder Lambretta project originally created by Innocenti in the late 1960s which unfortunately never went into production. Using the original drawings as inspiration, the engine was brought up to modern-day specification but still using some of the original ideas and ethos. Finally bringing the dream to fruition was the result of collaboration between Tino Sacchi and an engineer who works at the Brembo factory, Franco Dell'Acqua. More recently, the TT250 has grown to a TT275, the previous model had a two-cylinder 24hp engine with a 247cc displacement, compression was 8.6:1 and it had two Dell'Orto 26mm Power Jet carbs. It also had Varitwin-electronic ignition, special five-plate clutch and carbon silencer. Now the oversized TT275 also has two 30mm carburettors instead of 26mm. Other subsequent changes to port layout, along with reed valve and twin expansion chamber options, have made the engine capable of 30+hp. The additional five-speed gearbox and six-plate clutch upgrades have also made the engine better able to cope with higher levels of torque and strong power delivery.
The cost of all this is expensive due to limited production runs and many one-off parts being required. The engine produces good power, can be set up with small (26mm) carbs and a Clubman, or large (30mm) carbs and expansion pipes. Being an opposing twin the biggest advantage and this smoothrevving engine sounds like no other. It is capable of good acceleration and good top-end cruising speeds, with correct gearing. Even though it uses two carburettors, when set up and balanced correctly fuel consumption is still economical.
Tuning suggestions: Due to its high price and that it is only made in small numbers, the Targa isn't the first choice when it comes to tuning. After all, why pay so much for an engine then try to make it into something else? Tino built this as homage to the original Innocenti item, it was planned as a Grand Tourer, and that is how it should be seen. Tino also built in a degree of reliability, by not maxing the bhp. Having said all that, since its introduction, the TT has been reworked extensively both by owners and now Tino alike. The 275cc versions, with five-speed gearboxes, reed-valve and twin exhausts are seeing up to 40hp in some cases, where the cylinder ports have been reworked also. It's a stunning engine, however if all-out bhp is your end goal, that can be had cheaper elsewhere, but never with the sound of a twin… that is unique!
Manufacturer/Supplier: Casa Performance RRP: £592
Year launched: 2017
Average estimated power output: 2628bhp
Bore: 66mm
Stroke: 58mm
Capacity: 198cc
Induction type: reed valve
Standard port timings: Exhaust 190° - Transfer 124°
Overview: This kit is essentially the ‘baby brother' of the larger 225 versions. Obviously, though, this 200cc-X6 item fits the small-block casings (125-175 cases) and the 225cc-X7 discussed above fits the large-block casings (200). As you would expect, it is almost a carbon copy of the larger version, with practically identical port design and layout, with only a few very subtle differences in overall specs. The piston is a slightly different style, although still a highquality forged item with race spec rings, and the Casa website also lists the option at point of purchase to select either a centre plug or side plug option on the centre squish head.
Tuning suggestions: Being based on the 2015 ESC and 2016 BSSO race-winning cylinders, these are marketed as a fairly fruity item off the shelf. When a kit enters the market with 17hp at the back wheel, there is usually a tonne of ‘low hanging fruit' to be had in terms of power, and the first few hp are usually cheap and easy. But when a kit like this enters the market at 26, 28, or 30hp… then the gains are harder to come by and often more expensive. In the case of this kit, any gains would be made, usually, by a professional tuner adjusting the port timings, carb settings, ignition timing, and exhaust chamber measurements… and measuring each adjustment on a dyno to confirm the work is going in the right direction. Thankfully, the clever people at Casa have released an updated version of this, in the same way they did with the 225 variant. Named the X6e, it also features enlarged transfer ports, inlet port and boost port, as well as increased gasket face surface area.
Manufacturer/Supplier: Casa Lambretta RRP: £405
Year launched: 2021
Average estimated power output: 18-21bhp
Bore: 70mm
Stroke: 58mm
Capacity: 223cc
Induction type: Piston ported
Standard port timings: Inlet 144° - Exhaust 176° - Transfer 130° - Boost 134°
Overview: Having briefly delved into the cylinder kit market with a Casa 186cc and 210cc kit a few years back, Casa Lambretta is once again joining in with this new and vastly updated/upgraded item. It features an aluminium Nicasil lined barrel with five ports. The cylinder is made by Gilardoni, the manufacturers of the TS1, who are renowned for their quality and finish. The rear boost port runs through a matching cut-out in the rear of the piston skirt. The exhaust port is a rather nice design, offering larger width at the top (to aid with blowdown) and narrower width at the bottom (to decrease fresh charge short circuiting via the transfers) all of which should aid performance. The kit also has a concentric head with special fins to aid cooling. The Vertex forged piston for the kit is fluoro-carbide coated to reduce friction and wear.
Tuning suggestions: The kit is barely announced, so it wouldn't be fair to say too much on this point yet… but if we think along the lines of other 225cc piston-port kits, taking into account port timings, port area, exhaust, carb, ignition, gearing options and so on… you won't be far off the mark.