The Vespa T5 was the most groundbreaking traditional engine Vespa ever produced. Despite only making 12bhp, it gave a learner legal scooter the performance of a 200.
Us scooterboys always wanted more though…
25bhp coming right up!
SIP have just released their brand new 199cc Vespa T5 Performance kit which will increase a T5 engine to around 25bhp from the original engine’s 12…
Like the original, this aluminium cylinder has five transfer ports. The extra capacity has been achieved by upping the bore size to 65mm and by using a 60mm long stroke crank with a 115mm conrod.
SIP Dyno
The Dyno show SIP’s ‘plug & play’ set up, which uses Pinasco Master engine casings, SIP 60mm crank, Vape ignition, SIP 199cc kit, standard 24.24 SI carb, SIP Race Supersport clutch, DRT primary gearing and. SIP Road 3.0 exhaust.
If you already have a set of decent T5 casings, you can build this engine for around £1200.
In this specification, it makes 23.1PS (22.78bhp) and 24.1Nm (17.75 ft.lbs of torque), but it would be pretty easy to increase that.
More power?
According to SIP, there is plenty of scope to tune the cylinder and casings further to match, and there is also the option to go for reed induction.
Transfer ports
The SIP PERFORMANCE 199 cc cylinder has a modern and very effective 5-channel transfer port system. It has been designed so that the cylinder can be installed plug & play on the original transfer ports of the T5 Engines and thus functions perfectly. However, the channels in the cylinder have been shaped in such a way that they offer potential for expansion at the transition to the crankcase. The bridge between the transfer ducts in the original T5 crankcase can also be optionally removed to further optimize the transition.
Three-part exhaust duct
The exhaust duct is designed in three parts: a large central outlet and a side outlet on each side. The secondary outlets run inside the cylinder studs. With the help of numerous test bench tests, SIP have developed a special shape that ensures sufficient cross-sectional area for the secondary outlets to work effectively.
Exhaust flange
The T5’s exhaust flange is designed so that the exhaust is pushed into the flange piece on the cylinder and fitted. As the original manifold diameter is designed for 125 cc, SIP decided to design the flange piece on the cylinder so that it can be screwed on. The cylinder is supplied with a flange that is compatible with T5 exhaust systems. It is fastened with two screws, sealed with an O-Ring and also offers the option of attaching springs. However, it is also possible to replace the flange with a version with a larger diameter. Threads with a larger radius have been used for this purpose. This allows exhaust systems with a larger exhaust manifold to be adapted.
Crankshaft with 60 mm stroke and 115 mm conrod
The SIP PERFORMANCE 199 cc cylinder is designed for use with a 60 mm stroke crankshaft and a 115 mm conrod. The 60mm corresponds to the maximum stroke that can be realized without machining the crankcase. The longer conrod compared to the original T5 connecting rod with a length of 105 mm is an adaptation to the increased stroke. The rule of thumb for the connecting rod length is stroke × 2. Remaining at 105 mm while the stroke increases to 60 mm would have had a negative effect on the smooth running of the engine. With the SIP 60 mm stroke/115 mm crankshaft, the T5 engine retains its highly praised running smoothness.
Piston and head
The 65 mm piston has two 1 mm thick steel piston rings and a biconical gudgeon pin. As is usual with T5 engines, the head has a centered spark plug. The squeeze area is 47 % of the piston area. The combustion chamber engages in the cylinder and thus ensures perfect centering. The option of using the original centring bushes still exists, but is not required in the plug & play setup. The head and cylinder are shaped so that the original rubbers can be fitted for vibration dampening.
VIDEO: SIP’s Vespa tech guru, Jesco explains all about the kit in this video.
Technical details
- Coated aluminum cylinder
- 65 mm bore
- 60 mm stroke
- 5 transfer ducts
- 3 outlet ducts
- Bolted exhaust with O-Ring gasket
- Self-centering cylinder head
- 2 × 1 mm piston ring steel
- Timing: 122° / 180° / 29°
- Recommended squish 1.45-1.6 mm
- Recommended spark plug: NGK B8ES
- Recommended ignition timing: 18°
Parts included
- Aluminum cylinder with coating
- Cylinder Head with centering
- Piston 65 mm
- 2 × 1 mm Piston Rings
- Exhaust flange with fitting and O-Ring seal
- 2 × Gasket Cylinder Base (0.2 and 0.5)
199cc Vespa T5 shopping list
SIP Performance 199cc kit: £335, 60mm crank: £262, SIP Vape ignition: £306 SIP Road 3.0 exhaust: £120, Flywheel cover bridging piece: £34, SIP Supersport clutch: £276
Arriving very soon!
Prices are plus VAT and import duty (if applicable), or speak to your nearest SIP dealer. The kits are available to pre-order now and will be arriving very soon.
