Carb Diaphragm (Throttle Slide Piston) :: Hyosung GT125R GV250 GT250R GV125

Description

Carb Diaphragm (Throttle Slide Piston) :: Hyosung GT125R GV250 GT250R GV125

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After many years of hard use, old worn throttle slide pistons (also known as carb diaphragm ) should be replaced during a rebuild or carburettor overhaul to maintain optimal performance.

Damaged, sticky, or torn diaphragms cause a variety of issues including surging, poor fuel metering, bogging, and inconsistent throttle response. A healthy carb diaphragm plays a critical role in regulating fuel flow, ensuring your carburettor delivers the correct air-fuel mixture as designed.

The item location is shown in the pictures above (#33) ^

FOR 125CC TWINS: YOU WILL RECEIVE 2 PIECES ⚠️ This is required for both carburettors on twin-cylinder models. Check pictures above for reference.

FOR 250CC TWINS: YOU WILL RECEIVE 1 PIECE 🚦 Need 2 diaphragms? Add quantity 2 at checkout (for 250cc twin owners).

NEEDLES ARE NOT INCLUDED

🚚 UK Shipping: Delivery in 2-3 working days via 1st Class Royal Mail.
🌍 Global Shipping Available: Contact us for a fast quote here.
🛠 Fitting Instructions: Simple swap & go. No special tools required!
Need help? Visit our fitting tutorial guides.

🏍 Model Fitment:

GTR & RC	GT Naked (Comet)	GV Aquila/Mirage
125cc – All carb models	GT125 – All carb models	GV125 – Up to 2017
250cc – All carb models	GT250 – All carb models	GV250 – All carb models

📖 Reference OEM Part Number(s): 13338HG5100

🛒 For other carburettor parts, browse our shop or contact us for help or to inquire about other parts not listed yet. 👍 We can source most Hyosung parts you need!

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🛠 Install Tips & Advice

Replacing your carb diaphragm (throttle slide piston) is one of the most impactful maintenance steps you can take to restore smooth throttle response and consistent fuel delivery. Over time, diaphragms become brittle, sticky, or torn, which causes uneven fuel metering and throttle hesitation. If you experience surging, bogging, or an inconsistent engine idle, your carb diaphragm is likely a culprit.

When replacing, ensure you remove the carburettor carefully to avoid damaging the delicate diaphragm or other parts. Clean the carb bowl and throttle body area thoroughly before installing the new diaphragm to prevent dirt and debris from affecting the carburettor’s operation. Always inspect the carburettor jets, float valves, and needle position at the same time for a full tune-up.

Remember, this replacement does not include the carburettor needles. If you are tuning your carburettor for performance, consider upgrading or adjusting the needles to match your desired air-fuel mixture.

For enthusiasts looking to optimize carburettor performance, our community forums have excellent DIY guides on needle tuning, carb jetting, and balancing the mixture between lean and rich settings for better power and fuel efficiency.

Additionally, we stock stainless steel screws and other essential carb parts in our shop, making it easy to replace worn hardware or upgrade components during your rebuild.

Taking the time to maintain your carburettor with fresh diaphragms and correct tuning will ensure your Hyosung delivers smooth throttle response, better fuel economy, and a more enjoyable ride for years to come.