How to replace and maintain the spark plug of your 125cc motorcycle?

1 - The first thing to do is to remove the antiparasite fixed to the spark plug by pulling on the suppressor itself and not on the wire, then remove the casings or covers which may prevent access to the spark plug.

2 - Very important : Clean the spark plug well with a brush or a compressed air blower to release any impurities that could fall into the cylinder when you remove the spark plug. Loosen the spark plug one or two turns and start the cleaning operation again, to remove the last dirt that could remain stuck.

3 - If the candle is blocked: try to unblock it by forcing it with a spark plug remover more suitable (sometimes a longer lever is enough). If it still resists, run your engine for a few minutes. Expanding the cylinder head may solve the problem. If it is loose, but resists unscrewing a little too much, spray with penetrating.

4 - Place your cleaned spark plug (or your new spark plug) and screw it in first with your fingers, this is very important. If you do not enter straight it will block, whereas with the spark plug remover you risk "messing up the thread" of the cylinder head. Screw it in this way over several turns, ideally up to the sealing joint.

Tip: put a drop of copper grease, or graphite grease on the thread of the spark plug you are installing. It will be removed more easily during your next spark plug removal operation.

5 - Once the candle is screwed in by hand, finish with the spark plug wrench. To ensure ideal tightening, it is best to have a torque wrench and to respect the tightening torque indicated par the constructor. If you don't have one, it is generally advised (once the sealing washer is seated on the cylinder head) to make a 1/2 turn to 3/4 turns blockage. (Depending on whether the spark plug has already been used or not, and therefore whether the seal has already been crushed, or not).

Advice: If you do your maintenance yourself: chain maintenance, oil change, replacement of brake pads, cleaning or replacement of the air filter... Do not hesitate to invest in a torque wrench, Car the tightening torque is very important!

6 - Before replacing the anti-parasite, take the opportunity to clean it (compressed air, brush, alcohol...). The contact surfaces must be perfectly clean and neat. If it is oxidized, replace it.