The Casa casing, already fitted with a dedicated crankshaft from Primatist.
The Casa casing, already fitted with a dedicated crankshaft from Primatist.

With original Indian SIL casings running out of stock the race is on to produce the best alternative. We’ve already run an article on the various options here.

This engine casing – now named the Casa Case – has been developed by the guys at Rimini Lambretta Centre for the Casa Performance line. The idea was to make the casing as adaptable and affordable as possible. Admittedly there are those in our scene that think anything attached to Rimini Lambretta Centre also has a gold-plated price tag but we’ve been assured that this project has been designed as a mass-market solution rather than a high-end piece of exotica.

The prototype in the photos is sand-cast but if it performs as expected during testing then the plan it to pressure die-cast it using the same manufacturing method as the original Innocenti casings. Die casting is much more expensive to set up with regards to tooling but it massively reduces the unit production costs. It also results in something with a much-more aesthetic external finish.

logo CasaCase2

Unique features of the Casa Case:

  • It is highly adaptable and can accept stock cylinders or be machined to suit a selection of outrageous large capacity 2-stroke cylinders including some forthcoming Casa Performance kits which are expected to make in excess of 55hp!
  • It is designed to split vertically in order to fit a crankshaft rather than loading via the mag housing orifice.
  • It is designed around wider, larger diameter, longer-stroke crankshafts made by Sandro from top Italian crankshaft specialists Primatist. The crank for this engine will be 100mm diameter and 50mm across the big-end (instead of 40.5mm). 64mm stroke will be easily possible with enough meat in the casings to stroke to 66mm, 68mm or even more if required.
Proud parents...
Proud parents…

Other important features of the casing are:

  • This casing uses a special slim drive-side bearing that maintains the con-rod axis in the standard position. This means that previous types of Lambretta performance exhaust can be used without modification.
  • Strengthened engine mount castings. These were insisted upon as a safety measure after Casa Performance’s racers snapped two standard casings during the ESC race series and cracking another at Cadwell Park. Original casings are not really up to outputs of over 30hp.
  • A massively-enlarged gasket face allowing the fitment of anything from conventional Lambretta barrels to other exotica. They are currently claiming that the Casa Case “has the largest gasket face of any Lambretta engine in the Universe.”

The Casa Performance casing is also designed to take two new SS cylinder kits which are on the way. These exploit external studs; which permits improved internal porting without the limitations imposed on normal Lambretta kits. This modification makes it possible to release more power for the same capacity.

These new Casa SS kits are:

  • 225cc with 58mm stroke and 70mm piston
  • 250cc with 64mm stroke and 70mm piston

A third option is being considered that uses a 78mm bore and a 72mm stroke crank, giving a 345cc engine capacity. However despite the massive engine size, the lads at RLC are confident that the same power can be obtained from the 250cc configuration.

CAD model showing the case with a new cylinder fitted called RSS250...
CAD model showing the case with a new cylinder fitted called RSS250…

In addition a special side casing will be developed with room for a bigger clutch (6 or 7 plates is possible) and an improved clutch actuator using a rack and pinion mechanism similar to the Vespa PK XL housing, to offer the lightest possible clutch action. The side casing is designed to be backwards-compatible with original Lambretta engines so it is possible to use the new Casa clutch (which includes a cush-drive based on a racing kart layout) on normal Lambretta engines. A special 10mm-longer kickstart shaft is under development to match this casing.

One particularly interesting aspect of this engine is the rear brake set-up. It is reverse-compatible with Lambretta drum-brake components however there are two innovative and upgraded solutions on offer to improve matters.

  • A twin leading-shoe drum brake conversion will be offered. This uses a cam at both ends of the shoes to massively improve brake performance using the same method employed on all vintage GP bikes before they all swapped to disc brakes.
  • The next upgrade option is an external rear hydraulic disc brake conversion.

Writing as someone who feels that the standard Lambretta rear drum brake is not really up to the job of a standard Lambretta, I particularly welcome these developments.

SLUK were first to reveal this casing to the world via our Facebook feed prior to its display at the BSSO racing Annual General Meeting where it was approved for use in the Specials race categories.

Drive-side oil-seal replacement is now a much quicker job...
Drive-side oil-seal replacement is now a much quicker job…

When can I get a Casa Performance casing and how much will it cost?

In terms of timing there may be a few sand-cast prototypes kicking around some of the high-end scooter tuners in the very near future for development purposes. If you wanted one of those then you’d need to be in the know.

As soon as the casing is approved it will enter mass-production and we can expect to see the final versions arriving this summer.

As regards the question of cost; we’ve been assured that the basic engine casing is targeted to sell for “less than you’d think”.

Interesting times in the Lambretta world…

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