YS Engine YSE1274 Precision Sub-Needle for DZ170 CDI  [YSE1274]

Precision sub-needle for DZ170 CDI carburettors

The YS Engine YSE1274 sub needle is intended as a replacement item for the DZ170 CDI engine family. It sits inside the needle valve and plays a small but critical role in metering fuel for idle and the transition band.

Functionally, this sub needle determines how the main needle seats and meters flow; swapping in a correct, undamaged sub needle restores consistent seating and smoother fuel control. The component is aimed at model glow engines and serves as a maintenance and tuning spare.

Installation guidance: remove the carburettor top or needle retainer following the engine manufacturer's service instructions, extract the old sub needle, fit the new unit, and reassemble carefully. Keep the area clean and avoid contaminating seating surfaces. Do not over-tighten retainers and check for debris that could impede seating.

Tuning tip: even subtle differences in sub-needle condition change throttle response during idle-to-mid transitions. Make methodical, small needle adjustments and log each step to preserve a retraceable setup. If idling is inconsistent or the engine floods or surges, examine the sub needle before altering other components.