Vespa Super Sprint VBA VBB GT/R GL VGLA/B 2 Port BGM PRO 177 Cylinder Kit

BGM PRO 177cc cylinder for Vespa Largeframe 2-port engines

✅ Performance plus suitable for everyday use

The BGM177 cylinder is a very powerful, durable conversion cylinder that is fully suitable for everyday use. It covers a wide range of possible applications. The power of a 125cc standard engine can be more than doubled simply by replacing the cylinder.

In the version for Vespa Largeframe engines with 2 overcurrent channels, a 2 mm thick base gasket is used. The cylinder is prepared for this.

✅ Plug & play replacement for the original cylinder
✅ Power like a 200cc engine with the same reliability
✅ Low consumption and long range

Compatible with all standard components. Only the jetting and spark plug should be adapted. Older SI20/17 carburetors should be replaced by SI20/20 with long air filter.

Features

Aluminum cylinder, hard-coated (nickel-silicon carbide)
63 mm bore
Displacement with 57/60 mm stroke: 177/187 ccm
Cast piston with high silicon content
Two 1 mm steel piston rings
Recommended crushing edge with 57 mm stroke: 0.8-1.2 mm
Recommended crushing edge for 60 mm stroke: 1.0-1.2 mm

✅ Cylinder head

CNC-milled from the solid. The combustion chamber is recessed 4 mm into the cylinder, which simplifies the squish edge adjustment and ensures perfect sealing. Also prepared for temperature sensor. Compression ratio: 10.3:1.

✅ Further tuning

With 24 mm carburetor + BGM BigBox Touring, approx. 15 hp and 17-19 Nm are already available.

Performance-enhancing measures:

Suitable exhaust system (e.g. BGM BigBox Touring, Polini Box)
Larger carburetor (e.g. BGM PRO Faster Flow SI24)
Long-stroke crankshaft with extended intake angle
Electronic ignition (e.g. BGM666SP1)
Machining of intake duct/rotary slide valve
Enlargement of the overflow channels in the housing and cylinder base

✅ More displacement and power

Prepared ex works for 60 mm stroke: 187cc total displacement. Control angles increase as a result.

Recommended head gasket: 2 mm (optionally available).

✅ Ignition

Contact ignition can still be used, but should be in very good condition. Better: Maintenance-free electronic ignition. Recommended setting: static 19° from TDC.

✅ Control angle

57 mm stroke: overcurrent 118°, exhaust 171° (with 0.2 mm base gasket / 0.5 mm head gasket)
60 mm stroke: overflow 123°, outlet 173° (with 0.2 mm base gasket / 2 mm head gasket)

Head gasket for 60 mm stroke not included - see accessories.

✅ Gearbox

Many extend the transmission ratio at an early stage by replacing the clutch pinion (e.g. 23/65 or 24/65). Alternatively: Install a directly reinforced clutch. Recommendation:

Vespa Sprint (10") with touring-oriented exhaust: at least 23 teeth
PX125 gearbox with long stroke: 24/65 can also be ridden without problems
8" tires: e.g. 24/64 possible

Conclusion

A versatile plug & play cylinder kit with early onset power, a wide usable rev range, very high reliability, low consumption - and an excellent price-performance ratio.

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