Help needed,anyone know what size drain plug is on a 5.5 hp. Honda motor?

[Bruce L]

Have an Airblo vacuum pump with a 5.5 hp. Honda gasoline engine I purchased from Leader,decided to change the engine oil,drain plug is in such a position that the oil drains all over the base,so decided to put an extension on to drain the oil off to the side. Guessed at the size,thought maybe 3/8”, plug looks to be about the size of a 3/8” bolt. Even tried it in my drill index,will thread through the 3/8” size,next size up 13/32” plug slips through. Anyway,ordered up a 3/8” street elbow and 6” nipple from local hardware store ( as can’t go in and verify size) , was way too big,looks more like almost 3/4”. Ordered 1/4” street elbow,nipple,seems as large as my index finger,still way too big. Says made in China,do they not measure the same as us? Would like to get an extension of some sort to be able to drain the engine without oil going all over the place.
Thanks in advance for your help

[maple flats]

Try a metric pipe thread, be gentle turning, don't force it. The threads are in aluminum which can be damaged easily.
On my older Honda I extended the oil drain, I think it was a 1/4 pipe thread, (but that was about 10-12 yrs ago, and the engine was made in the U.S.

[carls47807]

It’s probably a 1/4” npt, which is similar in size to a 3/8” fine thread bolt.


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