Small-batch and handmade, the Sacre cases for Vespa allow the use of liquid-cooled Minarelli Horizontal Scooter parts that fit into a Vespa subframe. It's important to note that stock subframes and Ciao frames will not fit this motor without heavy modification. If you're looking for bolt-on/in power, the Polini Speed Cases or Malossi Reed Valve Motor are still the best option.
That said, I ploughed through most of the research for anyone state-side looking to build one of these, given you have had the chance to grab a set of cases.
Please note: This info is not broadly generic for all case-sets doing similar things. There are a few manufacturers in Italy creating custom carters for a similar purpose but this only applies to the Sacre cases.
The majority of the off-the-shelf components used to build these are for MInarelli Horizontal Scooter motors, which were used on a plethora of modern scooters. Trying to list them all would be hard, but the easiest ones to remember are the Yamaha Aerox and Jog RR, Aprilia SR50, MBK Booster and Malaguti F12 Phantom. across all sites, I found the best results looking for Jog RR/Aerox parts, as these scooters have a huge following overseas. Next best is the MBK Booster.
The one exception to this parts sourcing is the intake and reeds, which are taken from late-model Vespa scooters which include the Vespa ET2 and Piaggio Zip/Typhoon. And intake will mount to the cases, but carb angle and position will require attention depending on your subframe situation.
Any crank for the above Minarelli horizontal motors will work great, and there are multiple options from almost every aftermarket parts maker. The important factors when choosing a crank are your pin size and intended stroke.
Just like standard Vespa moped motors, Minarelli cranks can be had in 10 and 12 pin small ends. I have heard arguments for each size, but personally choose 10 pin cranks when it's an option. This only really matters in that it will dictate which kit you can choose from.
Stroke is a larger questions when it comes to these motors. Unlike most mopeds, scooter tuning and kit manufacture includes a multitude of stroke lengths to increase the displacement of the motor. Whether you choose standard stroke (39.2mm) up to ~45mm. Choose your adventure.
As with a lot of the other components to this build, variators from a variety of bikes will work. Mine in particular is a Polini intended for Malaguti F12. The main difference is that the variators are meant to be run movable face inward on the original bikes. In this arrangement on the Sacre cases, it would swing the belt 25-30mm away from the subframe, which puts it wildly out of line with the rear variator (whether you are running a stock rear variator, hybrid shaft with scooter rear clutch, or the fully-fabbed setup from Italy).
Thankfully, the crank’s splined design allows the entire assembly to be flipped, with some consideration to be run in the normal orientation.
Intake and Reeds
The Sacre cases are designed to take Vespa ET2/Piaggio Zip reeds and intakes. These are a large 2-bolt reed block with v-style reeds. I have both Polini and Athena aftermarket blocks, but a good condition stock block with fiber/carbon reeds added to it is a good option as well.
The Treats Sacre bundle comes with a short, aluminum spigot mount intake with an ID of 28mm. This means that PHBG’s are probably the smallest carb you will want to deal with. Polini CP’s, Polini PWK’s and OKO’s are all great options as well. I will be testing with both a 24 and 28 PWK to see if the extra volume is usable on these cases.
In my findings, you will have to clearance the cases to fit the reed block screws on the aftermarket blocks. Nothing that 5 minutes with a Dremel and sanding drum couldn’t handle.
Definitely the most satisfying part, the cylinder can come from an liquid-cooled Minarelli Horizontal bike, but it’s very important that the cylinder you buy matches the stroke. Other than that, live your dream.
As an aside for non-scooter people (like me), the scooter world uses a bunch of different qualifying terms for the design of their cylinders. You have stock, sport, touring, race, and full race (along with hybrid combo’s of those) cylinders that basically describe the porting and output to be expected. Unlike moped cylinder manufacturers and resellers, the scooter kit people are very specific to mention that the longevity and durability of a race-style cylinder is much lower than that of a cast-iron touring kit. Keep your end goals in mind, and buy a cylinder that will match the intention of your build.
Quick Assembly Notes
TEST FIT EVERYTHING.
These cases are hand-made in small batches, so there is a lot of room for small deviances. In my case, the piston skirt was impacting the bottom of the case casting which I did not discover until after the crank had been installed.
These cases also are made to be sealed with Tri-bond case sealant, so don’t bother making a gasket as it will a) be incredibly tedious and b) create enough room for things to float in an unneeded manner.
I will be adding to this once I have had the chance to get the subframe in from Italy, and it is mounted on the bike.