Choosing the Right Spark Plugs for Your 1960-1969 BMW R50/2
Get the right spark and avoid common headaches with this guide to new aftermarket spark plugs for your vintage BMW.
- You must verify if your R50/2 needs short (1/2") or long (3/4") reach plugs before buying.
- Always choose non-resistor spark plugs for the R50/2's magneto ignition system.
- Set the spark plug gap to 0.6mm (0.024 inches) for reliable performance.
- Modern aftermarket brands like NGK and Champion are excellent, readily available replacements.
Symptoms of Failing Spark Plugs
Worn or fouled spark plugs can cause a number of noticeable problems. Because the R50/2 has a simple magneto ignition, it is very sensitive to the condition of its plugs. You might notice one or more of these signs:
- Hard Starting: The engine is difficult to kick start, especially when cold. 🎬 Watch: Proper starting sequence for a vintage BMW R50S
- Rough Idle: The engine runs unevenly or stalls when stopped.
- Misfiring: You may feel the engine hesitate or stumble during acceleration.
- Loss of Power: The motorcycle feels sluggish and won't rev up properly.
- Increased Fuel Consumption: Inefficient combustion from a weak spark can cause the bike to use more fuel.
- Visible Fouling: The plug tip may be covered in black, powdery soot (fuel fouled) or a wet, oily residue (oil fouled). An engine that is running rich is a common cause of fouled plugs.
Critical Check: Short vs. Long Reach Plugs
Before buying, you MUST determine if your R50/2 has short reach or long reach cylinder heads. Using the wrong plug can cause severe engine damage. Short reach plugs have 1/2-inch (12.7mm) threads, while long reach plugs have 3/4-inch threads. Many long reach heads are stamped with the letters "LK" near the spark plug hole. Always compare your old plugs to the new ones before installing.
Choosing the Right Aftermarket Spark Plug
While original brands for the R50/2 were Bosch or Beru, modern aftermarket plugs from NGK and Champion are excellent, reliable replacements that often meet or exceed original quality. For the R50/2's 6-volt magneto system, it is highly recommended to use non-resistor spark plugs to ensure the strongest possible spark.
Brand Tiers
- Tier 1 (Recommended): NGK & Champion
Both NGK and Champion are trusted brands that make quality plugs for vintage bikes. NGK is frequently recommended by owners for its reliability. A common choice for the R50/2 is the NGK B8HS. Champion plugs, such as the L87YC and its cross-references, are also a solid choice. - Tier 2 (Premium): NGK Iridium
For owners seeking the best performance and longest life, NGK offers Iridium plugs like the BR8HIX. These have a fine wire tip that creates a more focused, consistent spark, which can improve starting and throttle response. They are more expensive but last much longer.
Pro Tip: When installing new plugs, apply a small amount of anti-seize compound to the threads to prevent them from getting stuck in the aluminum cylinder head. Do not overtighten; tighten by hand until the gasket seats, then give it a 1/4 to 1/2 turn with a wrench.
Known Issues
A known problem on these vintage bikes is stripped or spinning spark plug threads in the aluminum cylinder heads. This can happen from overtightening or simple wear over many decades. If a plug feels loose and won't tighten properly, the threads are likely damaged. This is a serious issue that requires a machine shop to repair by installing a thread insert, such as a Helicoil.
🎬 See how to repair stripped threads with a Helicoil kit| Type | Price Range |
|---|---|
| New Aftermarket (Standard) | $3.57 - $8.00 |
| New Aftermarket (Iridium) | $9.00 - $14.32 |
| New OEM (Bosch/Beru NOS) | $10.00 - $20.00+ (if available) |
Frequently Asked Questions (FAQ)
What is the correct spark plug gap for a BMW R50/2?
The correct spark plug gap is 0.6mm (0.024 inches). Always verify the gap with a feeler gauge before installation, as they can be knocked out of adjustment during shipping.
🎬 Watch: How to properly gap your new spark plugsShould I use a resistor or non-resistor spark plug?
You should use a non-resistor spark plug. The R50/2's magneto ignition system produces a better spark with non-resistor plugs. Using a resistor plug (often marked with an 'R' in the part number) can weaken the spark, leading to hard starting and poor performance.
How do I know if I need short or long reach plugs?
Check your cylinder heads. Many, but not all, long reach heads are stamped with "LK" near the plug hole. The safest method is to remove your old plug and measure the threaded portion. A short reach plug has 1/2-inch threads, while a long reach has 3/4-inch threads.
What does the color of my old spark plug mean?
The color can tell you about your engine's health. A light tan or grayish-brown color indicates a healthy engine and correct air-fuel mixture. A black, sooty plug means the engine is running too rich. A wet, oily plug can indicate a problem with piston rings or valve guides.
Helpful Videos
Technical Specifications
OEM Part Numbers: Bosch W240 T1 Bosch W240 T2 Beru 240/14
Spark Plug Gap: 0.6mm (0.024 in). Thread Diameter: 14mm. Thread Reach: 12.7mm (1/2 in) OR 19mm (3/4 in) - MUST VERIFY. Wrench Size: 20.8mm (13/16 in).
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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.