A new 199cc racing cylinder for Vespa T5 models is now available from SIP Performance, unlocking the full potential of one of Vespa’s most distinctive engines. Designed as a plug-and-play solution, the SIP 199cc cylinder offers a powerful, reliable upgrade while retaining the smooth character the T5 is famous for.
The standard Vespa T5 engine has a displacement of 125cc, but its crankcase and cylinder layout allow for significantly greater capacity. SIP is the first manufacturer to fully exploit this potential in a production tuning kit, increasing displacement to 199cc using a 65mm bore and 60mm stroke.
To achieve this configuration, the cylinder is designed to run with a 60mm stroke crankshaft and a 115mm connecting rod. This combination represents the maximum stroke possible without machining the crankcases. Importantly, the longer connecting rod maintains correct geometry and preserves the T5 engine’s renowned smooth running, avoiding the vibration issues that would occur with the original 105mm rod.
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Advanced transfer port design
The SIP 199cc cylinder features a modern five-channel transfer port system, carefully designed so it can be installed directly onto the original T5 transfer ports. This allows the cylinder to function effectively without requiring case modification, making it ideal for both road riders and tuners.
Three-port exhaust layout
Exhaust flow is handled by a three-part exhaust duct, consisting of a large central outlet and two secondary outlets positioned within the cylinder stud area. SIP developed this layout through extensive bench testing to ensure sufficient cross-sectional area and efficient gas flow from all outlets.
Modular exhaust flange
Unlike the original 125cc design, SIP has opted for a bolt-on exhaust flange, sealed with an O-ring and secured by two screws. The supplied flange is compatible with standard T5 exhaust systems, but it can also be replaced with a larger-diameter version to suit high-performance exhausts. Larger-radius threads allow for easy adaptation to aftermarket manifolds using springs or alternative fixing methods.
Piston, head and cooling
The kit includes a 65mm piston fitted with two 1mm piston rings and a biconical gudgeon pin. As with all T5 engines, the cylinder head features a central spark plug. The combustion chamber engages directly into the cylinder to ensure perfect centring, with a squish area covering 47% of the piston surface.
Despite the longer connecting rod, the cylinder can still be run with the original Vespa T5 cooling cowl, using spacing to account for the increased height.
Technical specifications
- Coated aluminium cylinder
- 65mm bore
- 60mm stroke
- 5 transfer ports
- 3 exhaust ports
- Bolt-on exhaust flange with O-ring seal
- Self-centring cylinder head
- 2 × 1mm piston rings
- Port timing: 122° transfer / 180° exhaust / 29° blowdown
- Recommended squish: 1.45–1.6mm
- Recommended spark plug: NGK B8ES
- Recommended ignition timing: 18°
The SIP 199cc Vespa T5 Racing Cylinder has been developed to deliver strong, usable power straight out of the box, while still offering extensive scope for tuners to push performance even further.
More information is available from www.sip-scootershop.com.
