Choosing the Right Spark Plug for Your 1973-1977 Ski-Doo Olympique 300S
Keep your vintage Olympique running strong with the correct, fresh spark plugs.
- For this vintage sled, aftermarket spark plugs from NGK (AB-6, AB-7) or Champion are the standard.
- Always check the spark plug gap before installation; it should be around 0.020 inches.
- Symptoms of a bad plug include hard starting, misfiring, and rough running.
- Carrying spare plugs and a wrench on the trail is a cheap and simple way to prevent being stranded.
Signs of a Failing Spark Plug
A bad spark plug is a common reason for a poor-running vintage snowmobile. Because they are inexpensive and easy to change, they are often the first thing to check. Symptoms of a failing plug include:
- Hard Starting: If the engine turns over but won't fire up, especially when cold, the spark plug may not be providing a strong enough spark.
- Engine Misfires: You might feel the engine hesitate or stumble during acceleration. This can be caused by an inconsistent spark.
- Fouled Plugs: Upon inspection, if the end of the spark plug is black, wet, or oily, it's 'fouled'. This prevents a good spark. Fouling is common in two-stroke engines and can point to other issues, but often a fresh plug is the immediate fix.
- No Spark: In some cases, a complete failure of the plug or other ignition components can result in no spark at all.
Choosing the Right Aftermarket Spark Plug
For a vintage machine like the 1973-1977 Olympique 300S, original equipment (OEM) spark plugs are no longer a practical option. The good news is that aftermarket brands like NGK and Champion offer high-quality, reliable replacements that are readily available and affordable. In the vintage sled community, both brands are used, but NGK is often preferred for its consistent performance in two-stroke engines.
Brand Comparison
| Brand | Common Part Numbers | Notes |
|---|---|---|
| NGK | AB-6, AB-7 | Often recommended in forums for reliability and resistance to fouling in vintage two-strokes. The AB-7 is a slightly hotter plug than the AB-6, which can help prevent fouling if you do a lot of low-speed riding. |
| Champion | (Cross-references to NGK) | A long-standing, reliable brand that produces equivalent plugs. Quality is generally considered good, though some users report more fouling issues compared to NGK in certain applications. |
Pro Tip: Always carry a few spare spark plugs and a plug wrench with you on the trail. A fouled plug can happen unexpectedly, and being able to swap it out in a few minutes can save you from a long walk home.
Aftermarket Spark Plug Cost
The cost for a new aftermarket spark plug for your Olympique 300S is very reasonable. Expect to pay within the following ranges for a single plug.
| Part Type | Price Range (per plug) |
|---|---|
| New Aftermarket (NGK, Champion) | $3.61 - $14.32 |
| New OEM | Not Available |
Frequently Asked Questions (FAQ)
How often should I change the spark plug?
For a vintage two-stroke, it's good practice to inspect the plug every 10-15 hours of operation and replace it at the beginning of each season, or more often if you experience fouling. Given their low cost, frequent replacement is cheap insurance against being stranded.
What is the correct spark plug gap for the Olympique 300S?
The recommended spark plug gap is typically between 0.018" and 0.020". Always verify the gap with a feeler gauge and adjust if necessary before installing a new plug.
Should I use NGK or Champion plugs?
Both are quality brands, but many vintage sled enthusiasts prefer NGK plugs like the AB-6 or AB-7 for their reliability in two-stroke engines. If your sled runs well on a Champion, there is no harm in continuing to use it, but if you experience issues, switching to an NGK is a common troubleshooting step.
What does the color of my old spark plug mean?
Reading the plug is a great way to understand how your engine is running. A light, tan-brown color on the insulator indicates a healthy engine. A black, sooty plug means the engine is running rich (too much fuel) or the plug is too 'cold'. A wet, oily plug indicates fouling. A white or blistered insulator means the engine is running too lean (not enough fuel), which can cause serious damage.
Are there any recalls or bulletins for the spark plugs?
No. There are no recalls or technical service bulletins (TSBs) from Ski-Doo or the NHTSA related to the spark plugs on the 1973-1977 Olympique 300S. Any issues are related to normal wear, maintenance, or other engine conditions.
Technical Specifications
{ "Recommended Plug (Standard)": "NGK AB-6", "Recommended Plug (Hotter)": "NGK AB-7", "Thread Size": "18mm", "Wrench/Hex Size": "15/16 Inch", "Spark Gap": "0.018 - 0.020 in (0.45 - 0.50 mm)" }
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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.