Spark plug socket size for 175

[Joe]

Title says it all . What size socket for a HS 175 spark plug. I did a search and no result…thanks !

[czmike]

Hi Joe,

13/16" AF (Across the Flats) is the size socket you need to remove or refit standard spark plugs in your HS175.
This is a very common spark plug hex size used in older engines. Use a proper Spark Plug Socket which has a a rubber insert inside to stop you breaking the porcelain insulator of the plugs which is hard, brittle & easily cracked.

Thanks to the long history of engine and spark plug development the sizes & threads used for plugs are confusing.
The thread of the spark plugs is Metric (14mm x 1.25) as is the terminal for the HT lead (M4 = 4mm x 0.7) but the hex for the socket is Imperial (13/16").

Best Regards,
Mike Munday (also HS175 owner),
Australia

[Joe]

Thanks! Appreciate the information!