There is no way that carb would work in a hundred years for that application..I'm sure I don't need to tell you but the top mount where the throttle cable screws in is angled completely wrong. The cable top would be pointed straight at the frame..
I'd call the seller out on the fact that this part is an impossible fit and shouldn't be listed for the 250ES/SX and request it go back with shipping paid..
Don't re-invent the wheel for that F^&$ed part!!
I see the problem though. All the Ebay replacement carbs are the same style..what gives?
For another $30ish you could have one of FlyingW's beauty rebuild carbs..no brainer solution to me!!
Current toys..
1986 Honda 350X..trail bomb!
1985 Honda 250SX..my main mudder
1985 Honda 250ES..Back in Black Trike
Current non-trike toys:
1990 Honda TRX300FW
1995 Seadoo GTX
1998 Polaris Indy Lite 340(Nearly new looking)
1998 Polaris Touring 500
1998 Club Car (electric)