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Exhaust Silencer
Air Filter
Compression Ratio
Crankcase Stuffing
Cylinder Head
Electronic Ignition
Engine Ports
Exhaust Silencer
Expansion Chamber
Magneto Ignition
Spark Plug
Transmission Roller

Eliminating 4-Stroking

THE VeloSoleX S 3800  has a Pot-type Exhaust Silencer.

The engine is prone to 4-stroking at high RPM (engine firing on alternate sparks due to an over-rich mixture). To eliminate this 4-stroking, an additional 5.5 mm hole (shown) must be drilled in the bottom of the Exhaust Silencer. To allow the Exhaust Silencer to be returned to normal, tap this additional hole with an M6 Coarse Thread Cutter. To return Exhaust Silencer to normal, fit a short M6 Bolt with Split Washer.

This extra hole is also recommended if you want to provide an Exhaust Oil Drain or if you want to increase the Carburettor Venturi Diameter (see Carburettor section).

Exhaust Hole


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Copyright 2008 BRIAN'S VELOSOLEX. All rights reserved. This is a personal website containing information for and by VeloSoleX enthusiasts. It is not intended to replace any official information and whilst every effort is made to ensure the accuracy of all published information no guarantee is offered nor liability accepted for any loss or damage that may arise from any errors or omissions.