Briggs and Stratton’s small engines power everything from lawn mowers to portable generators. But when one of these trusty engines refuses to start, the ignition coil often takes center stage. Understanding the Briggs and Stratton ignition coil resistance chart is your first step toward diagnosing the issue and keeping your equipment running.
Briggs and Stratton Ignition Coil Resistance Chart
Single-Cylinder Engines
| Model Series | Primary Resistance (Ω) | Secondary Resistance (kΩ) |
|---|---|---|
| 450E | 0.5 – 1.5 | 5 – 7 |
| 500E | 0.4 – 1.2 | 5 – 7.5 |
| 550EX | 0.5 – 1.4 | 5.5 – 8 |
| 625EXi | 0.6 – 1.6 | 6 – 8.5 |
| 675EXi | 0.5 – 1.5 | 6.5 – 9 |
| 725EXi | 0.5 – 1.5 | 6.5 – 9 |
| 800E | 0.4 – 1.3 | 5.5 – 8 |
| Classic 35 (92908) | 0.3 – 0.7 | 2.5 – 5 |
V-Twin Engines
| Model Series | Primary Resistance (Ω) | Secondary Resistance (kΩ) |
|---|---|---|
| Intek V-Twin | 0.3 – 0.7 | 4 – 6.5 |
| Professional V-Twin | 0.4 – 0.9 | 4.5 – 7 |
| Vanguard V-Twin | 0.5 – 1.0 | 5.5 – 8 |
| 44T977 (Commercial) | 0.4 – 0.8 | 5 – 7.5 |
| 49M777 (Professional) | 0.4 – 0.9 | 4.5 – 7 |
Commercial Series Engines
| Model Series | Primary Resistance (Ω) | Secondary Resistance (kΩ) |
|---|---|---|
| XR Series | 0.6 – 1.1 | 5 – 7 |
| CR Series | 0.5 – 1.3 | 6 – 8 |
| 2100 Series | 0.7 – 1.2 | 6 – 9 |
| 8200 Series | 0.6 – 1.2 | 5.5 – 8.5 |
| 950 Series | 0.5 – 1.4 | 5 – 7.5 |
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Ideal Resistance Ranges Explained
Resistance values help you judge coil condition:
- Primary resistance: This is the low-voltage coil (measured between positive and ground terminals). Typically under 2 ohms.
- Secondary resistance: High-voltage winding (measured between spark plug lead and coil ground). Ranges between 4k–10k ohms.
Symptoms of a Faulty Ignition Coil
- Engine cranks but won’t start
- Poor spark or no spark
- Backfiring or misfiring
- Inconsistent engine performance
- Hard starts or stalling
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Step-by-Step Resistance Testing Guide
- Disconnect spark plug wire.
- Remove ignition coil from engine.
- Set your multimeter to ohms (Ω).
- Measure primary resistance between terminals.
- Measure secondary resistance from spark lead to the ground terminal.
- Compare to the chart above.
Note: Always test with the engine off and cool!
Troubleshooting Tips
- Low resistance? Possible short circuit or melted windings.
- High resistance? Internal corrosion or broken winding.
- No reading? The coil is open or completely failed.
How to Replace a Faulty Ignition Coil
- Remove the blower housing.
- Unscrew the old coil.
- Gap new coil using the business card (typically 0.010 – 0.014 in.).
- Secure and reconnect the spark wire.
- Test spark before final reassembly.
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FAQs
How many ohms should a Briggs & Stratton coil have?
A typical Briggs & Stratton ignition coil should have:
- Primary resistance: Between 0.3 to 1.5 ohms
- Secondary resistance: Between 4,000 to 9,000 ohms (4kΩ to 9kΩ)
Exact values depend on the engine model. Always refer to a resistance chart or your engine’s manual for specifics.
What is the normal resistance of the ignition coil?
The normal resistance for most ignition coils is:
- Primary side: Around 0.5 to 1.5 ohms
- Secondary side: Between 5kΩ and 8kΩ
Too low or too high readings suggest a short or open winding and may mean the coil is faulty.
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How do you test a Briggs and Stratton coil with a multimeter?
To test a Briggs & Stratton ignition coil:
- Disconnect the spark plug wire.
- Remove the ignition coil from the engine (for accurate testing).
- Set your multimeter to Ohms (Ω).
- Measure:
- Primary resistance between the two small terminals.
- Secondary resistance from the spark plug lead to the coil ground.
- Compare your readings to standard values.
If your readings fall outside the normal range, the coil may need replacement.
What is the gap between the ignition coil and flywheel on a Briggs and Stratton engine?
The recommended air gap between the ignition coil and the flywheel magnet is typically:
- 0.010 to 0.014 inches (0.25 to 0.36 mm)
You can use a business card or feeler gauge to set this gap accurately during installation.
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How many ohms is a 12V coil?
For a standard 12V ignition coil (used in cars and some larger engines), resistance values are typically:
- Primary: Around 1.5 to 3 ohms
- Secondary: Anywhere from 7,000 to 12,000 ohms (7kΩ to 12kΩ)
Briggs & Stratton engines usually don’t use automotive 12V coils unless modified.
Why is my Briggs and Stratton engine not sparking?
Common reasons for no spark include:
- Faulty ignition coil (out of resistance range)
- Bad spark plug
- Broken flywheel key
- Disconnected kill wire
- Improper coil gap
- Flywheel magnets are dirty or weak
Use a multimeter and spark tester to narrow down the cause.
