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

Replacement sub needle for DZ170 CDI engines

The YS Engine YSE1274 sub needle is supplied as a direct replacement intended for DZ170 CDI carburettors. In RC glow engine setups it performs the metering role inside the needle valve assembly, helping to control fuel flow for idle and mid-range mixture adjustments.

In operation, the sub needle sits within the needle valve body and establishes seating and metering characteristics. Replacing a worn, bent, or damaged sub needle reinstates predictable seating and smoother mixture control, making it a useful spare for routine maintenance and tuning jobs.

Installation notes: follow the engine maker's recommended service steps to access the carburettor needle assembly, remove any needle retainer or carb top as required, replace the sub needle, and carefully reassemble. Avoid over-tightening retainers and remove any burrs or debris that could prevent correct seating. After refit, run the engine in and recheck main and idle needle settings.

Tuning advice: small changes in sub-needle condition affect how the needle seats and will influence throttle response through idle and transition. Make small incremental adjustments and record settings so you can return to a known baseline. If you experience erratic idling, flooding, or lean surging, inspect the sub needle before replacing other parts.