How to Test Ignition Coil & Set Spark Plug Gap on Agricultural Weeders
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7HP & 9HP Power Weeders & Rotary Tillers
Direct gear-drive petrol & diesel weeders for sugarcane, cotton, and horticulture. 32-blade rotary with state subsidy invoice.
A spark plug that sparks outside the engine in open air may still fail under high compression pressure inside the cylinder if the ignition coil is deteriorating or the spark gap is incorrect.
Specifications & Setup Standards
- Correct Spark Plug Gap: Exactly 0.70mm to 0.75mm (measured with a wire feeler gauge). Too wide a gap strains the coil windings; too narrow produces weak combustion and carbon fouling.
- Ignition Coil to Flywheel Air Gap: Set to exactly 0.30mm to 0.40mm. Place an ordinary business card between the magnetic flywheel pole and the ignition coil legs, tighten the mounting bolts firmly, and pull the card out.
Symptoms of a Failing Ignition Coil
- The machine starts effortlessly when cold in the morning.
- Operates normally for 20 to 25 minutes, then starts misfiring and abruptly dies once the engine reaches full operating temperature.
- Refuses to start until the engine cools down completely for 30 minutes, after which it fires right back up.
- Remedy: Replace the encapsulated ignition coil; internal copper windings are expanding and breaking contact under heat.
Farmer Equipment & Fuel Calculator
Avoid engine seizure from incorrect 2T petrol mixing and verify 26mm/28mm 7T/9T brush cutter attachment compatibility before ordering replacement parts.
Need This Machine or Fitting Spares for Your Farm?
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Eligible farmers can get 40%–50% subsidy on farm machinery. Check your state's active scheme, eligible models, document checklist, and official DBT portal.