I was trying to figure out what kind of thread size the OS MAX FS 70 engine uses for its exhaust connector port. I am talking about the following (green circle)

OS FS 70 image

I could not find this in the manual, just the replacement parts but not what the thread size is. I have tried to use my measurement device and it seemed to be a 10mm hole, however using an M10 screw, it just slid into it like nothing. An M12 screw was too big. There are no M11 screws where I am from. I suppose it might be an imperial thread size, and I have absolutely 0 experience with that.

Does anyone happen to know what the thread size for that exhaust port is?


Does this chart have your engine on it?


There looks a similar engine number that has 11mm x 0.75mm exhaust thread -

enter image description here

Look like it is a metric fine 11mm.

I just did a search on google for “OS MAX FS 70 exhaust thread”

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