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MMW Killercase - Bavaria's answer to the subject of the ultimate Lambretta touring engine

CNC machined motor housing -Made In Germany- around the Simonini light aircraft cylinders in the Li family's Lambretta. The Simonini cylinders with 80 mm x 80 mm hole pattern fit, which are available with 70 mm and as Big Bore with 72,8 mm bore.

The specification of the killer case turns the engine concept into an over-touring engine. Even with a 28 mm or 30 mm carburettor and our bgm Big Box Sport, the 30 hp mark on the rear wheel is scratched or exceeded.

Simonini's Mini Evo cylinders are machined to fit under an original Lambretta cylinder hood. In the Killercase, the inlet sits directly above the crankcase and was made for a type RD350 membrane. By placing the intake system above the crankcase and thus the lower connecting rod bearing, the entire engine concept can be operated permanently and without problems at 1:50.

Apart from the engine housing, the cylinder, (due to) the crankshaft and the intake manifold, conventional Lambretta parts are used to build and complete the killer case. So all parts of the Li series can be used. So all Lambretta ignitions fit for dl/ GP cone, fan wheel housing, all drive components, gears and small parts.

The gearbox cover plate is included in the scope of delivery and is fastened with eight M8 screws. With the correct torque (22 Nm), Schnorr washers and Loctite, this is probably the safest solution for finally fastening the gearbox cover plate.

The killer case is constructed like an original case and all parts can be taken over from the conventional Lambretta engine. With the side hood installed, the Lambretta does not look like it has had a fresh cell treatment.

We offer the killer case in conjunction with the Big Bore cylinder (72,8 mm bore) and a crankshaft with a 64 mm stroke, giving you a displacement of 265 ccm.

crankshaft

Our crankshaft with 64 mm stroke, 120 mm connecting rod and 18 mm piston pin is a German-Italian co-production. The crank webs come from Cosmoto from Turin, the connecting rod from Mazzuchelli and is actually for a Fantic 249 Strada. Helmut von pressed, straightened and shortened the crankpins to the right size www.az-zweitakt-power.de

The work on each shaft is documented, the shafts are numbered and there is a video for each shaft that documents the round trip.

We also checked the running clearance of all cylinders at Helmut and had them adjusted to 0.05 – 0.06 mm if necessary. Better safe than sorry and so (provided the ignition and, above all, the carburettor settings are correct) the engine is fully gas-proof after half a tank of fuel.

The concept is expressly designed as a stable touring engine with a rev range that is easy to use on the road; with full suitability for everyday use, good consumption values ​​and high compatibility with well-known Lambretta components.

Further advantages of the killer case concept:

  • Deco hole for easy launch
  • Torque from idle
  • A 2% oil admixture is sufficient, as the inlet is located above the crankshaft and the lower connecting rod bearing is already sufficiently lubricated
    Unobtrusive, almost production-like appearance, only visible under the side panels
  • Can be driven without modification of the sheet metal parts and with the standard tank
Lambretta exhaust test Big Box Reso racing exhaust

Lambretta resonance exhaust and Big Box prototype test

A Lambretta exhaust test: the new and upcoming Lambretta Big Box is currently in production. A delivery date is unfortunately still unknown.

Exhaust test on the Scooter Center Performance test bench

 

The Lambretta exhaust systems in the test

Before we sent the final sample to Spain, the new box was put through its paces again. Lambretta exhaust test: Another prototype box from our friend Chalky from Replay Scooters and JPP  came directly to the test bench:

  • bgm PRO BigBox Proto
  • JPP box prototype

The following resonance racing exhaust systems competed against the pits:

  • the TSR Evo,
  • the JL3 and
  • in MB3

And all three Reso systems did better against the speakers than we would have expected!

The Lambretta exhaust systems

 

The Lambretta engine

The test engine was constructed as follows:

 

Result & conclusion of the test

Nice and clear to see how good the box is from the start Performancebut also with plenty of torque scores in comparison to the 'racing exhaust systems'.

This is exactly what makes the bgm PRO boxes so nice to drive. There is always enough power available without having to struggle with gear connection problems or having to turn the gas like crazy to get things going.

The moderate consumption values ​​of the engine concepts with the bgm boxes are another advantage, apart from the original look and the pleasant background noise. Another outstanding feature is the protected fastening system with adjustment options in both horizontal and vertical directions. This allows tolerances and, above all, spacers used to be compensated for different strokes and connecting rod lengths.

Lambretta exhaust test performance charts

Here you can find the performance diagrams as PDF: