An air injection system is used on ff–1, 1300G and all 1975 models
A belt driven air pump is used to supply air, under pressure, to air distribution manifolds which have openings at each exhaust port. Injection of air at this point causes combustion of the unburned hydrocarbons in the exhaust manifolds, rather than allowing them to escape into the atmosphere. An anti-backfire valve controls the flow of air from the pump to prevent backfiring which results from an overly rich mixture under closed throttle conditions.
Check valves prevent hot exhaust gas backflow into the pump and hoses in case of pump failure or when the anti–backfire valve is not working.
Air pumps are equipped with a relief valve to discharge excess air which the pump produces at high engine speed.
On 1300G models, an additional air by-pass valve is used. When the manual choke is pulled out, the air by-pass causes the air from the pump to flow into the air cleaner rather than the exhaust manifolds, which prevents the manifolds from being overheated.
| Fig. 1: 1300G air injection system — ff–1
and 1975 models similar
|
