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Tillotson HW 42g Inlet Tension Spring
24C-298 Tillotson 42g Inlet Tension Spring
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Tillotson HW 42g Inlet Tension Spring

Part Number: 24C-298
Online Price: $2.10
Tillotson 24C-298 Inlet Tension Spring – 42g Pop-Off Spring for Diaphragm Carburetors
Availability: In Stock.

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Description

24C-298 Tillotson 42g Inlet Tension Spring – OEM Pop-Off Spring for HW, HB, HC, HL, HR, HM, HX Carburetors


The Tillotson 24C-298 42g Inlet Tension Spring is a genuine OEM component used to regulate pop-off pressure and control fuel flow in high-performance diaphragm-style carburetors. Designed to fit a wide range of Tillotson carburetors—including the popular HW series—this 42-gram spring is one of the most common standard pop-off springs used in karting and other small engine racing applications.


Key Features:

  • Genuine OEM Tillotson part for consistent performance and reliability
  • 42-gram pressure rating, ideal for tuning HW and other series carburetors
  • Helps maintain clean and responsive acceleration by regulating fuel delivery
  • Installs between the fulcrum arm and carburetor body to control diaphragm action
  • Fits Tillotson HW, HB, HC, HL, HR, HM, and HX series diaphragm carburetors


Tuning Tip from the Track:

For optimal performance in most 2-stroke racing engines, set pop-off pressure as low as possible while still achieving clean, crisp throttle response—especially out of corners. Too low, and you risk bogging. Always tune pop-off after dialing in needle settings, and use new diaphragms to ensure accurate testing and carb behavior.

Fine-tune pressure by:

  • Swapping springs with different gram ratings
  • Adjusting fulcrum arm height
  • Adding shims under the spring for subtle changes


Compatible Carburetor Series:

  • Tillotson HW
  • Tillotson HB / HC / HL / HM / HR / HX

This spring is a trusted go-to for racers and tuners alike aiming for consistent fuel delivery and throttle performance on the track.

FAQ

Q1: What does the 42g Tillotson inlet tension spring do?

A1: It controls the pop-off pressure of the carburetor by providing resistance to the diaphragm and fulcrum arm. This directly impacts fuel flow at low engine RPMs and throttle response.


Q2: Which Tillotson carburetors is this spring compatible with?

A2: The 24C-298 spring fits a wide range of Tillotson diaphragm carburetors, including:

  • HW
  • HB
  • HC
  • HL
  • HM
  • HR
  • HX series


Q3: When should I change my inlet tension spring?

A3: Replace the spring if you experience inconsistent pop-off pressure readings, poor throttle response, or tuning difficulties. Springs can weaken over time or deform with repeated adjustments.


Q4: What is the ideal pop-off pressure for 2-stroke racing engines?

A4: There’s no one-size-fits-all answer—it varies by carb, fuel, and engine. However, you should aim for the lowest pressure that still maintains clean acceleration, especially out of corners. Use this spring as a tuning baseline.


Q5: Can I adjust pop-off pressure without replacing the spring?

A5: Yes, small adjustments can be made by shimming the spring or adjusting the fulcrum arm height. However, for major changes, swapping to a spring with a different gram rating is recommended.

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