The rewind starter, also known as the recoil starter, was introduced by Jacobsen in 1928 and has since become standard for small engines. While the constructional details differ, rewind starters have the following basic components: • Pressed steel or aluminum housing, which locates the starter center over the flywheel center. • Recoil spring, one end [...]
Small engine governors put a ceiling on no-load speed and hold rpm relatively constant under varying loads. Less expensive engines typically use air vane governors of the general type illustrated in Fig. 4-29. The spring tends to close the throttle; the dynamic head of cooling air acting against the vane attempts to open the throttle. [...]
Briggs manufactures one-piece Flo-Jets in two sizes. The small version carries its main jet in the float bowl (Fig. 4-15A). The large model employs a remotely located main jet, supplied through a removable nozzle (Fig. 4-15B). Needle & seat Service as described for the two-piece Flo-Jet (Fig. 4-11). Note that the replacement seat must be [...]
Figure 4-2 illustrates the Vacu-Jet mechanism, which is distinguished by a single pickup tube and tandem discharge ports controlled by flow through a single jet. Figure 4-22 shows the three basic forms of this carburetor.The Pulsa-Jet derives from the Vacu-Jet and in its various permutations uses many of the same parts. The distinction between the [...]
Figure 4-16 is a sectional view of the crossover Flo-Jet, as used on horizontal crankshaft Model 253400 and 255400 engines. This carburetor includes a vacuum-operated fuel pump, illustrated in the next drawing. Needle and seat renewal and float adjustment procedures are as described for the two-piece Flo-Jet. Figure 4-17 illustrates the assembly sequence for the [...]
Two spring-loaded dogs inside a pressed aluminum retainer transmit starting torque to the flywheel hub. A compression pin or screw secures the retainer to the underside of the sheave and the sheave to its axle. Note that some retainer screws have left-hand threads. Warning: Wear eye protection when servicing rewind starters, particularly during and subsequent [...]
The factory appears to be slowly phasing out the Flo-Jet series in favor of highly modified Walbro carburetors. Engines in the 9-to 13-cubic-in. range use variants of the small series Walbro, recognized by its angular appearance and removable air bleed jet, mounted just aft of the air cleaner. The removable main jet nozzle has been [...]
Small, medium, and large two-piece Flo-Jets are the only up-draft carburetors in the Briggs line. Figure 4-4A shows the parts layout common to all three models. Needle & seat Extract the elastomer seat by threading a self-tapping screw into the fuel orifice (Fig. 4-11). Press in a replacement seat—PN 230996 for gravity feed, PN 231019 [...]
Carburetors do not wear out in the accepted sense of the term. Most failures are associated with “soft” parts, such as inlet needles and seats, diaphragms, and gaskets. After long service, the throttle shaft bearings might develop enough play to justify replacement, when such repairs are possible. Light varnish deposits respond to lacquer thinner and [...]
Pulsa-Jet carburetors include a fuel pump, which is actuated by a vacuum diaphragm. Side-mounted diaphragms are discussed in an upcoming section titled “Vacu-Jet & Pulsa-Jet.” The tankmounted diaphragm (Fig. 4-10), used on one version of this carburetor, concerns us here. Figure 4-6 illustrates the places where vacuum leaks typically develop at the tank interface. Figure [...]
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