How To Replace Spark Plug on Ryobi 4-Cycle Trimmer Head

Replacing the spark plug and oil on my Ryobi 4-Cycle is something I do every year to help keep my trimmer running well throughout the season.

I've had my Ryobi C430Trimmer for about 4 years now and in addition to the curved shaft string trimmer I have attachments that let me use it as an edger and even a garden tiller. It gets a lot of use and has been very reliable.

I made this quick video on how to replace the spark plug on my C430 power head.

You'll need a T20 torx driver or a flat head screwdriver to remove the engine cover and a 5/8" spark plug socket. I've had this Stanley 3/8" spark plug socket set for a number of years which includes a 5/8" socket as well as 3/4" and 13/16" sockets which has covered all the tools I own and even my car.

You'll also need a spark plug. This year I used an NGK CMR7A (978) because Amazon had it a little cheaper with prime shipping and I use NGK plugs in my car. In the past I've used the Champion RY4C (978) which worked well.If you want to try to find them locally Autolite 4194, Brisk SR14C should also work.