YS Engine YSE1274 Sub Needle — for DZ170 CDI Engines  [YSE1274]

Direct-fit sub needle for DZ170 CDI

The YS Engine YSE1274 sub needle is supplied as a replacement for DZ170 CDI models, intended to sit within the needle valve and govern fuel metering at idle and through the mid-range. It is a service part for model glow engines rather than a consumable upgrade.

The sub needle sets how the main needle seats and meters flow; installing an undamaged replacement reinstates predictable seating, which helps smooth mixture control and throttle behaviour. It is suitable for routine maintenance and tuning tasks.

Fitting notes: follow the engine manufacturer's procedure to access the carburettor needle assembly, remove the top or retainer as required, change the sub needle, and reassemble carefully. Ensure seating faces are free from burrs or grit and avoid over-tightening retainers. After refit, perform a measured run and re-adjust the main and idle needles to restore optimum mixture.

Practical tuning advice: sub-needle condition influences seating and throttle response across idle and transition. Apply incremental adjustments and keep notes to enable rollback to prior settings. If you experience irregular idling, unexplained flooding, or lean surging, inspect and, if necessary, replace the sub needle before investigating other components.