We often get to see what the big boys are up to around the world but some of the smaller, or less well-known scooter tuners, shops and ‘in the shed’ builders get overlooked. It’s good to know what’s happening in the crazy world of scooter tuning though – if you’re an overlooked genius get in touch.
Here’s one such development from Germany. It’s based on a Simonini microlight cylinder and mated to a piece of exquisite CNC machined billet aluminium. Creating a beautiful Lambretta engine with oodles of torque. Read on to find out more about it…
Why use a microlight cylinder?
Pros: The idea of using a Simonini cylinder in the Lambretta is not exactly new and has been tried by several people in Austria and Germany because this barrel is also perfect for use in a scooter. It has very good workmanship and durability, is designed for torque and has an acceptable price.
Cons: Unfortunately, the use of the Simonini was only possible with extensive welding and milling work to the original Lambretta engine casings. Meaning it’s not good for a simple ‘bolt-on’ job. Aggravating things further is the fact that the cylinder is controlled via a housing inlet with reedvalve.
Harald Grillhiesel (MMW) and Rainer Büsch had the perfect solution. They had to find… or create, a suitable casing!
What do MMW do?
MMW are a small family business who make and manufacture milled and turned parts for industry on modern CNC machines. Their passion lies in classic scooters though, so they also develop and manufacture Vespa and Lambretta parts including, Liedolsheim clutches, CNC manifolds, CNC heads and brakes for LTH, SIP, BGM and Jockeys Boxenstop. They also produce parts for karts and have their own in-house dyno for development of racing parts.
Harald has the technical possibilities and with Rainer at his side generating ideas the duo can make thoughts become reality. The Killercase is the result of one of those brainstorming sessions. The engine concept was never designed for the highest hp from the beginning. It was to be a high torque, reliable touring engine using as many standard Lambretta parts as possible to keep it cheap and easy to run.
After a few trials with the 70mm barrel, the decision was finally made in favour of the Evo Big Bore, with 72.8mm diameter. For the crankshaft, the choice fell on an available standard 62/116 from Primatist. This manufacturer had already shown in the Vespa sector that they can make excellent crankshafts.
But now the Simonini piston caused problems because it uses an 18 mm piston pin and has the wrong compression height. The constructors were not impressed by this. They simply had a piston manufactured by Wiseco according to their own specifications!
This brings the engine to around 260cc. Within a few days the housing was milled, the barrel was made to fit a standard air scoop, various cylinder heads were developed and things like intake and exhaust ports were made.
Already the first test bench runs were very promising. Their engine was producing 33hp at 6311 rpm and 37.45 Nm at 6113 rpm. This was using a 35 TMX carb, standard RD reedvalve and a TSR Evo exhaust.
6,000km of testing
Harald told us “This concept convinced me so much that I decided to build such an engine and test it on the way to Zakopane (Poland) and back. Unlike the first tests in Bavaria, I used a 30mm Polini PWK and a BGM Big Box exhaust. Also this combination worked very well but had minor thermal problems due to the small outlet of the box. Now I use the TSR Evo and a MB 5-speed gearbox with a final gear ratio of 4.20.”
Harald Grillhiesl’s testbed Series 2 ran the Simonnini Killercase 260 to Zakapone and back. Interestingly, this scooter also sports fuel injection with lambda control (microsquirt system).
“After more than 6000km the engine makes no problems at all, is relatively fuel-efficient and makes driving it incredibly good fun. In my opinion, a Lambretta should run like this!”
Only the racer who loves very high revs should not be happy with the “Simone.”
More to come
Everyone involved is still working on improvements. For example, intake manifolds are already offered in different diameters. In the near future new exhaust systems, especially for this engine, are to be developed and also a conversion of a Big Box is in work. Scooter Center will offer the proven big box V4, especially for the Simonini engine. The tailpipe will be enlarged from 16 to 25mm and a silencer will run under the engine. With this exhaust, according to first tests, almost 30hp is possible. An excellent option for a powerful touring engine.
Do you want to know more?
A new ‘Luxury for your scooter’ webshop has just been set up to sell most of the products used in this engine and of course the Killercase casings themselves. Plus there’s plenty more still to come…
Let them know that SLUK sent you in their direction.
Simonini Killercase 260 gallery
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