4 replies to this topic

[andymini12]

just wondering what is a vacuum pipe as iv seen people spaking about it and don't know what it is.
Andy

[SKIDDERWOLF]

Im pretty sure your on about the pipe that runs between the dizzy and the carb to advance the ignition

[MRA]

It's a thin (approx 2 to 3mm in diameter) often black plastic pipe.

[Redbaron6969uk]

and if u mean.....what does it do......as the engine revs faster a vacuum is created at the inlet end which creates suction on the advance/retarde gubins in the dizzy to adjust to suit enine requirement.

[TimmyG]

and if u mean.....what does it do......as the engine revs faster a vacuum is created at the inlet end which creates suction on the advance/retarde gubins in the dizzy to adjust to suit enine requirement.

Almost right.... the vac is created in the inlet manifold as the throttle is closed in and this advances the timing at part throttle to give better economy and throttle response. I.e at full throttle (inlet manifold open to atmosphere) there is no vacuum and therefore no vac advance. timing does advance with revs mechanically though via the weights and springs on the dizzy shaft.