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004 Inlet Tension Pop Off Spring
004 Inlet Tension / Pop-Off Spring
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004 Inlet Tension Pop Off Spring

Part Number: 004
Online Price: $2.00
004 Inlet Tension Pop-Off Spring for Precise Carburetor Fuel Delivery
Availability: In Stock.

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Description

004 Inlet Tension Pop-Off Spring for Diaphragm Carburetors


The 004 Inlet Tension Pop-Off Spring is a vital tuning component in diaphragm-style carburetors, helping regulate the rate of fuel delivery to both the high and low side circuits. This is especially important during low-speed engine operation, where precise fuel metering ensures smooth idling, responsive throttle, and efficient combustion.


The spring directly affects pop-off pressure—the pressure required to open the carburetor’s inlet needle valve. It’s important to note that pop-off pressure is not the same as fuel pressure. While the fuel pump typically delivers only around 1 PSI, pop-off pressure readings (e.g., 10 PSI) reflect the spring tension required to unseat the needle valve, not the system's fuel pressure output.


Pop-off pressure is determined by:

  • The spring tension rating (in this case, the 004)
  • The installation height of the spring in the carburetor assembly

The 004 spring provides a specific pressure range ideal for applications requiring precise low-end fuel control. It's commonly used in tuning two-stroke and small engine carburetors for smoother performance and better fuel response at lower RPMs.


Key Features:

  • Regulates pop-off pressure for consistent fuel flow
  • Ideal for tuning diaphragm carburetors in small engines
  • Helps stabilize idle and improve throttle response
  • Works with a variety of 2-stroke engine carburetor models
  • Precision-manufactured for reliable tension and performance

FAQ

Q1: What is the purpose of the 004 Inlet Tension Pop-Off Spring?
A1: It regulates pop-off pressure in diaphragm carburetors, determining when the needle valve opens to allow fuel into the metering chamber—especially at low RPMs.


Q2: Is pop-off pressure the same as fuel pressure?
A2: No. Pop-off pressure refers to the force needed to overcome the spring tension and open the needle valve. Fuel pressure is generated by the fuel pump and is usually around 1 PSI.


Q3: What types of engines or carburetors are compatible with the 004 spring?
A3: The 004 spring works with many small 2-stroke engines using diaphragm-style carburetors, including Tillotson, Walbro, and similar brands.


Q4: How do I adjust pop-off pressure using this spring?
A4: Pop-off pressure is adjusted by altering the spring’s installed height or switching to a spring with a different tension rating. A pop-off tester can be used for precise tuning.


Q5: When is the 004 spring the right choice?
A5: Choose the 004 spring when tuning for smooth low-speed performance, consistent idle, or when rebuilding a carburetor with a specific target pop-off pressure in mind.


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