After a little digging...
https://archive.org/stream/airplaneenginee00anglgoog/airplaneenginee00anglgoog_djvu.txt
MURRAY-WILLAT
The Murray-Willat Company built their first valveless rotary engine during 1910. These engines operated on the two-stroke cycle. A blower, integrally incorporated in the engine, compressed the air and forced fuel into the engine for the purpose of improving the performance at altitude. At the bottom of each cylinder were open exhaust ports which permitted complete scavenging, and the blowing of a blast of fresh air across the piston at the end of each stroke. The cylinders were turned from forged-steel billets. In addition to the large exhaust ports, there were small inlet ports that registered with deflectors provided on each side at the top of the piston. These directed the charge toward the top of the cylinder and thus prevented it from escaping through the exhaust ports before the piston had closed all ports on its upward stroke.
The crankcase was machined from solid steel forgings, the two halves clamping the cylinders in place between them. The connecting rods were mounted in a spool that was carried on two ball bearings. The crankshaft was made hollow for the purpose of providing a passage for the gas mixture from the blower into the crankcase where a pressure of 7 lbs. was maintained. Ignition was provided by a magneto.
Murray-Willat 90-h.p. Model
Following the experimentation with this type of engine, the Murray-Willat Company built two six-cylinder models. The smaller engine, which was rated 35 h.p. at 1200 r.p.m., had a 75 mm. (2,95 in.) bore, 90 mm. (3.54 in.) stroke, and a total displacement of 145.68 cu. in. The gasoline consumption was said to be .615 lbs. per h.p-hr,. and the oil consumption 2.8 lbs. per hr. The overall diameter was 25.98 in., and the
weight was reported to be 132.3 lbs., or 3.8 lbs. per rated h.p.
A larger model, rated 90 h.p. at 1200 r.p.m., had a 100 mm. (3.94 in.) bore, 130 mm. (5.12 in.) stroke, and a total displacement of 374.52 cu. in. The gasoline consumption was said to be .411 lbs. per h.p-hr.. and the oil consumption 2.3 lbs. per hr. The outside diameter was 29.0 in., and the complete weight was said to be 260 lbs., or 2.88 lbs. per rated h.p.
Sadly, nothing about having an even number of cylinders in a single row and cylinder ignition sequence. Maybe I'm missing something obvious.