New powervalve version of the GT rotax engine.
New powervalve version of the GT rotax engine.

 

Before Scooterist Meltdown Iggy tasked me with covering the new products there. I planned to jam it all into one article but there was so much on one stall that we’ve given Richard Taylor’s GT engineering project a separate article. And yes, the title does say Vespa, but not what you’d expect.

 

20200208-5530-800

 

Rotax GT Lambretta Engines

 

At Meltdown 2019 Richard showed-off the evolved Rotax water-cooled conversions for the GT cases that SLUK tested first back in 2017. This time those engines have developed to the stage where they are now full engine kits (baring a few parts you must supply) to convert your scooter to a water-cooled touring motor capable of 40hp+. As it stands Eden Bakewell has been running one of these engines for most of last year including the ride to Poland and back for Euro-Lambretta. Versions are currently available with non-powervalve barrels or with guillotine-type powervalve cylinders derived from Rotax watercraft engines.

 

non-powervalve version
non-powervalve version

 

Simonini Lambretta GT engines

 

If converting to water-cooling seems too much faff then Gran Turismo are one of several firms now offering Lambretta engines pre-configured to accept the popular Simonini air-cooled paraglider cylinder. It’s not as powerful as the Rotax conversions but it’ll fit under a cowling and run with a fan.

 

The main difference between the GT Simonini conversion and the competition – such as the Killercase we covered here – is in the casings, crankshaft and ignition. All are based on the cast GT casings (which are cheaper than CNC billet engines) but a revised version machined to accommodate special wide-web crankshafts. These crankshafts all have a flywheel taper machined to suit Aprilia RS125 ignitions; which are widely available and highly reliable in comparison to many of the aftermarket Lambretta offerings. Richards thinking is that larger web crankshafts will offer better engine balance for the large pistons used in these conversions and offer a smoother ride to anyone who’d like to use these engines for touring.

 

 Air-cooled GT engine modified to accept the Simonini 230cc paraglider kit: a cheaper and easier conversion than the Rotax.
 Air-cooled GT engine modified to accept the Simonini 230cc paraglider kit: a cheaper and easier conversion than the Rotax.

 

GT 300 engine for Vespa GTS

 

Finally, the pigeon amongst the cats was the proposed GT Valkyrie engine for Vespa, but not the geared type. The Valkyrie was presented in 3D printed concept form as a replacement engine for the Vespa GTS (or other Piaggio-based automatic scooters such as the Scomadi 250 or Royal Alloy 300). This would provide a 2-stroke engine that utilised all the same Rotax and crankcase-reed GT casing developments but packaged them into a twist-and-go format using the GTS layout.

 

The Valkyrie project prompts almost more questions than answers. Do the sort of scooter owners who ride automatics want a 2-stroke engine kicking out a predicted 40-50hp? Can a Vespa GTS belt-drive transmission cope with that kind of performance? Can the GTS chassis handle that kind of power and speed without tying itself in knots?

 

I think it’s fair to say that none of the gearshift scooter owners got it at all. Very few of the automatic riders got it either – many have started riding autos specifically to cover distances to rallies in comfort without ever getting their hands dirty. For them carburettors, mixing 2-stroke oil and frequent belt changes may be regarded as a retrograde step.

 

There were however a hardcore of scooter racers and scooter traders who do get it and liked the idea of a 40+hp Vespa that you can build with a chassis that’ll cost you less than a grand and comes already plumbed for water-cooling and with disc brakes front and rear. It’ll still have electric start as well.

 

As abhorrent and many classic scooter riders find modern scooters, the cost of classic and the desire by many to return them to original condition means that performance heads may soon need another way to get their kicks.

 

Richard had enough positive feedback to commit to making one example – using billet CNC casings – for testing.

 

GT Valkyrie 280-300cc powervalve 2-stroke engine conversion for the Vespa GTS and other Piaggio-powered autos. Prices form £3,350 + donor parts.
GT Valkyrie 280-300cc powervalve 2-stroke engine conversion for the Vespa GTS and other Piaggio-powered autos. Prices form £3,350 + donor parts.

 

In other news…

 

And at this point we haven’t even discussed the forthcoming GT reedvalve kits for the D and LD Lambretta models, but we can cover those in the future…

 

Photos and text: Sticky

 

There will be more tech from Scooterist Meltdown later this week

 

 

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