⭕ This is a 1910 Excelsior twin. Many think excelsior introduced the twin in 1911 but in fact the first factory mentions of a twin came out in January of 1910 and the first bike was sold in July. I believe that there is only one other 10 excelsior twin in existence and it is serial number T3XXX. This is T30XX and both of the case numbers match.

This particular engine was bought from an estate in Southern California around 10 years ago, and has been on display since. It was apparently converted to run a water pump at some point in its life. It is missing the magneto (it had a disintegrating pot metal modified 1925 Chevrolet distributor on it when I got it)
It turns over very nicely and has compression. It is missing the compression release cam for the rear cylinder and the linkage that connects the two. There are three broken fins on the front cylinder and none on the rear. I removed the rear cylinder and the piston and cylinder wall are in wonderful shape. Original excelsior piston and Rod and I saw no indications that it was oversize. The gears show very little if any wear. Its really quite impressive. Again judge for yourself but I dont see any evidence d any welding or repairs on the cases at all. The magneto mount will need to be repaired, as shown. Judge for yourself but I think if you were to find a magneto you would have a running motor fairly quickly.
Lots of original nickel plating left on the cylinders and there is still some remaining on the gear case and cover.