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EC Assorted Pop-Off Spring & Shim Kit
715 EC Assorted Pop-Off Spring & Shim Kit
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EC Assorted Pop-Off Spring & Shim Kit

Part Number: 715-K
Online Price: $32.95
Pop-Off Spring & Shim Tuning Kit for Tillotson and Walbro Carburetors
Availability: In Stock.

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Description

EC Pop-Off Spring & Shim Tuning Kit – For Tillotson & Walbro Diaphragm Carburetors


Fine-tune your engine’s performance with the EC Pop-Off Spring & Shim Kit, the ultimate tuning solution for Tillotson and Walbro diaphragm carburetors. Whether you're building for kart racing, performance engines, or small 2-stroke tuning, this kit gives you full control over your carburetor’s pop-off pressure—a critical factor in fuel volume regulation and low-end engine response.


This comprehensive kit includes 13 of the most commonly used inlet tension springs (part numbers: 001, 002, 003, 004, 005, 007, 008, 009, 011, 020, 021, 022 – 3 of each), plus .005” and .010” shims to make precise adjustments without needing to replace springs unnecessarily.


For accurate tuning, we recommend pairing this kit with either the POPG-1 (0–15 psi) or POPG-2 (0–30 psi) Pop-Off Pressure Gauges (sold separately).


Kit Includes:

  • 13 Spring Types: 001, 002, 003, 004, 005, 007, 008, 009, 011, 020, 021, 022
    Qty: 3 of each spring for repeated testing and tuning
  • Shim Pack: Includes both .005” and .010” shims
  • Fits Most Diaphragm Carburetors
    – Compatible with Tillotson, Walbro, and similar high-performance carbs
  • Perfect for Kart Racers, Tuners & Engine Builders


What Is Pop-Off Pressure & Why It Matters:

Pop-off pressure does not control fuel pressure. It’s part of the carburetor’s fuel metering system that determines when the needle valve opens to allow fuel into the metering chamber. We recommend setting the pop-off pressure as low as possible while maintaining crisp throttle response out of the tightest corner. 

  • Low Pop-Off Pressure = Easier starting, richer low-end, but risk of flooding
  • High Pop-Off Pressure = Leaner low-end and harder starting, but may help crisper throttle response
  • Proper tuning helps balance fuel delivery, idle quality, and throttle response

This kit gives you the tools to tailor your carburetor’s fuel delivery to the engine’s needs, track conditions, or weather changes.

FAQ

Q1: What is this kit used for?
A: It’s used to adjust pop-off pressure in diaphragm-style carburetors, like Tillotson and Walbro, by changing the spring tension or adding shims to fine-tune fuel volume at low RPM.


Q2: How do the shims work?
A: Shims are placed under the spring to increase its installed height, which raises the pop-off pressure without needing a stiffer spring—allowing finer adjustments.


Q3: Is this kit universal?
A: It fits most diaphragm carburetors used in karting, 2-cycle racing, and small engine performance builds. Always check spring dimensions to confirm compatibility.


Q4: How do I check pop-off pressure?
A: You’ll need a pop-off pressure gauge like the EC POPG-1 (0–15 psi) or POPG-2 (0–30 psi), which connects to your carburetor’s fuel inlet for accurate testing.

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