1. Low battery. Check the battery voltage to make sure it's above the recommended level. If the battery is low, charge it or replace it.
2. Faulty spark plug. Remove the spark plug and check it for damage or fouling. If the spark plug is damaged or fouled, replace it.
3. Dirty air filter. A dirty air filter can restrict airflow to the engine, which can prevent it from starting. Remove the air filter and clean it, or replace it if necessary.
4. Clogged fuel filter. A clogged fuel filter can prevent fuel from reaching the engine, which can prevent it from starting. Remove the fuel filter and clean it, or replace it if necessary.
5. Bad fuel. Old or bad fuel can cause the engine to run poorly or not start at all. Drain the old fuel and replace it with fresh fuel.
6. Electrical issue. There may be an electrical issue, such as a loose or damaged wire, that is preventing the engine from getting the power it needs to start. Check all of the electrical connections and make sure they are secure.
7. Engine problem. There may be an internal problem with the engine, such as a seized piston or a broken camshaft, that is preventing it from starting. If you suspect that there may be an engine problem, you should take your ATV to a qualified mechanic.
If you've checked all of these potential issues and your Honda Rancher 420 still won't start, you should take it to a qualified mechanic.
