Choosing the Right Spark Plugs for Your 2007-2017 Hyosung GT650
Solve common running issues and improve performance with the correct spark plug replacement.
- The standard OEM spark plug is the NGK CR8E, and a popular premium upgrade is the NGK CR8EIX iridium plug.
- Symptoms like rough idle, stalling, and lack of power are very commonly traced back to worn spark plugs on the GT650.
- Replacement requires lifting the fuel tank and moving the radiator to access both plugs, making it a moderately difficult job.
- Always check that the spark plug gap is set to 0.7mm-0.8mm before installation.
Signs of Failing Spark Plugs on Your GT650
Worn or fouled spark plugs are a common cause of engine problems on the Hyosung GT650. Many owners report that replacing the plugs is the first step to solving issues like rough idling, hesitation, and a general lack of power. If you notice any of the symptoms below, it might be time for a new set of plugs.
Choosing the Right Aftermarket Spark Plugs
When shopping for new spark plugs, you have a few good options. NGK is the original equipment manufacturer (OEM), making it a safe and reliable choice. Denso is another high-quality option. The main choice you'll make is between standard nickel/copper plugs and premium iridium plugs.
Brand & Type Comparison
| Brand Tier | Brands & Models | Description |
|---|---|---|
| OEM Standard | NGK CR8E | This is the standard plug for your bike. It offers reliable performance and is the most affordable option. It meets all of Hyosung's specifications and is an excellent choice for daily riding. The service manual recommends replacing these every 12,000 km (about 7,500 miles). |
| Premium Iridium | NGK CR8EIX, Denso IU24 | Iridium plugs are a popular upgrade. They have a fine-wire center electrode that provides a more focused, consistent spark. Owners report benefits like easier cold starts, a smoother idle, and slightly better throttle response. While they cost more upfront, they also last significantly longer than standard plugs. |
| Economy | Champion (e.g., 8698) | While Champion offers compatible plugs, they are less common among GT650 owners. Most riders stick with NGK or Denso, which are proven performers for this specific engine. For reliability, it's often best to choose the brands trusted by the owner community. |
Known Vehicle Issues
The Hyosung GT650 is not known for major spark plug-related recalls or technical service bulletins (TSBs). However, a recall (NHTSA ID: 08V071000) was issued for 2005-2007 models regarding a faulty fuel tank cap gasket that could cause stalling. While unrelated to the plugs themselves, the symptom of stalling can be similar. Additionally, some owners report that the original spark plug caps can crack over time, leading to a weak or lost spark. When replacing your plugs, it's a good idea to inspect the caps and wires for any signs of damage.
Cost of Replacing Hyosung GT650 Spark Plugs
You will need two spark plugs for your GT650. The price can vary based on whether you choose standard or premium iridium plugs.
| Item | Average Cost |
|---|---|
| New Aftermarket Plugs (Set of 2) | $10 - $58 |
| Shop Labor | $90 - $180 |
Common Ordering Mistake
Always check the spark plug gap before installation. The correct gap for the GT650 is 0.7mm - 0.8mm (0.028 - 0.032 in). While most plugs come pre-gapped, they can be knocked out of spec during shipping. Use a feeler gauge to verify the gap and adjust if necessary.
Frequently Asked Questions
How difficult is it to change the spark plugs on a GT650?
It's moderately difficult. The rear cylinder plug is easy to access once you lift the fuel tank. However, the front cylinder plug requires you to unbolt and carefully move the radiator to gain access. It is a DIY-feasible job for someone with basic mechanical skills and tools, including a 16mm thin-wall spark plug socket.
How often should I change my spark plugs?
The official service manual recommends replacing standard spark plugs every 12,000 km (approx. 7,500 miles). If you use premium iridium plugs, you can often double that interval, though it's still good practice to inspect them periodically.
Are expensive iridium spark plugs worth it for my GT650?
For many riders, yes. While they cost more, iridium plugs offer a longer service life and can improve starting and idle smoothness. If you want the best performance and fewer maintenance intervals, the upgrade to NGK CR8EIX or Denso IU24 plugs is a popular and worthwhile investment.
Do I need to put anti-seize on the new spark plug threads?
NGK, the OEM manufacturer, specifically recommends NOT using anti-seize compound on their modern spark plugs. Their plugs have a special trivalent plating that acts as its own lubricant and prevents seizing. Using additional anti-seize can lead to over-torquing and potential damage to the cylinder head.
Technical Specifications
OEM Part Numbers: 09482-00456
Socket Size: 16mm, Thread Diameter: 10mm, Thread Reach: 19mm, Gap: 0.7mm - 0.8mm. Quantity required: 2.
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The information in this article is provided for general reference and educational purposes only. Vehicle specifications, procedures, and part compatibility can vary by production date, trim level, and region. Always consult your vehicle's factory service manual and verify part numbers before purchasing or performing repairs. Safety-critical components such as airbags, seat belts, and braking systems should be installed by a qualified professional.
- Hyosung GT650: