DZ170 CDI Needle Valve Sub Needle Upgrade YS Engine YSE1274  [YSE1274]

Sub-needle designed for DZ170 CDI fitment

The YS Engine YSE1274 sub needle is supplied as an aftermarket replacement for DZ170 CDI carburettors. Its function is restricted to the needle valve assembly, where it helps manage fuel flow for idle and mid-range mixture control.

As a component, the sub needle defines seating and metering characteristics inside the needle valve; fitting a new, correctly shaped sub needle corrects seating irregularities and returns smoother mixture control. This item is intended as a spare for glow engine maintenance and tuning.

Fitting advice: access the carburettor needle assembly per the engine manufacturer's instructions, remove the needle retainer or carb top as needed, swap the sub needle, and assemble with care. Avoid over-torquing retainers and ensure seating surfaces are clear of burrs or debris that could affect metering accuracy. Conduct a controlled run-in and then re-tune main and idle needles to re-establish correct settings.

Tuning guidance: small changes to sub-needle condition can alter how the needle seats and will affect throttle response in idle and transition. Proceed with incremental adjustments and document changes so you can revert to previous settings if required. Inspect the sub needle early when you encounter idling issues, flooding, or lean surging.