In figure 19 the throttle slide (2) is shown in the idle position adjusted by the idle-speed screw (4). The air adjusting screw varies the mixture strength delivered by the idle circuit screwing in results in a richer idle mixture and vice-versa. To obtain the best engine running, it is worth finally rechecking by carefully readjusting the idle mixture screw (5).ģ.4.2 - Idle Setting with an air-adjusting screwĪn idle circuit with an air adjusting-screw adjusts the amount of air required to produce the mixture that the idle circuit has to supply during idling.
Then unscrew the throttle-stop screw (4) until you get the desired idle speed again. Screw in the idle speed screw (4) to get a slightly- higher speed than normal (about 1200 rpm for four-stroke engines and about 1400 rpm for two- stroke engines) then screw the mixture adjusting screw (5) in or out until you obtain the most even running. Always adjust the idle setting with the engine fully warmed up.
DELLORTO PHBH 28 TUNING FREE
The idle mixture adjusting-screw is always located downstream at the throttle.Ĭheck that the throttle cable has about 1 mm of free play with the slide closed. Mixture formed from fuel metered through the idle jet (6) and air metered by the calibrated passage (1) further mixes with air regulated by the throttle slide opening. In this position the vacuum present down stream of the throttle valve causes mixture to be delivered via the hole (3), regulated by the tapered tip of the mixture adjusting screw. In figure 18 the throttle slide 2 is shown in the idling position, adjusted by the idle speed screw (4). The adjusting screw meters the amount of mixture of a strength predetermined by the metering effect of the idle jet and the air corrector, and there fore on screwing in the mixture screw, idle fuel de livery decreases and vice-versa.
Finally, to obtain the best engine running, it is worth rechecking by very carefully readjusting the air-adjusting screw.ģ.4.1 - Idle setting with a mixture-adjusting screw
Then unscrew the idle-speed screw again until you obtain the normal idling speed. Screw in the idle-speed screw (4) to obtain a slightly-higher idling speed than normal (about 1200 rpm for a four-stroke engine or about 1400 rpm for a two-stroke) Then adjust the air- adjusting screw (1) to obtain the most even running. Always adjust the idle setting with the engine fully warm. Upstream of the slide there is only a weak vacuum, insufficient to cause the main circuit to deliver any fuel emulsion, while downstream of the slide there is a stronger vacuum which activates the idle circuit idle circuits are designed with either a mixture-adjusting screw or with an air adjusting screw.Check that the throttle cable has about 1 mm free play when the slide is fully closed. The engine needs only a small amount of air when idling and the throttle slide should therefore be almost completely closed. Dellorto Motorcycle Carburetor Tuning GuideĪt idle the Carburetor supplies only the mixture required to keep the engine running at very moderate rpm.
0 kommentar(er)
