You have the hollow rudder so that puts your motor after 1924. Yours has the single “carburetor” mixer so I’m thinking prior to 1927, as my Model J is 1927 and has the twin mixer. So my guess is 1925 – 26. Someone who knows better will chime in with corresponding model designation.
And be gently with the timer… remove and open it up, examine and clean. Let us know what you find. Hopefully not crumbled pot metal bushing.
Joe B
