NOTE: Muncie – Neptune models having a “U” in their model designation had under water exhausts . Example: OB2AU

Model Name: 1933 OB1
Original carburetor	Tillotson MS-73A
Magneto	Eisemann Model 71H
Cylinders	1
B x S
HP	2
Point gap	0.020
Sheer pin
Oil
Tank
Exhaust
Lower unit
Rope plate

Model Name: 1933 OB15 Waterwitch
Original carburetor	Tillotson MS-47A
Magneto	Eisemann Model 82D
Cylinders	2
B x S	2 1/2” x 2″
HP	16 @ 4000 RPM
Point gap	0.020
Sheer pin	7/32” x 1 1/2“
Oil	2/3 pt SAE40 per gal.
Tank	Sheet aluminum
Exhaust	Under water
Lower unit	Stream lined ball bearing
Rope plate	8″ Water Witch

Model Name: 1933 OB15A Master 16
Original carburetor	Tillotson MS-47B
Magneto	Eisemann Model 82D
Cylinders	2
B x S	2 1/2” x 2″
HP	16 @ 4000 RPM
Point gap	0.020
Sheer pin	7/32” x 1 1/2“
Oil	2/3 pt. SAE-30 per Gal.
Tank	Embossed aluminum
Exhaust	Under water
Lower unit	Stream lined ball bearing
Rope plate	8″ Neptune

Model Name: 1933 OB15G Sea Gull
Original carburetor	Tillotson MS-47B
Magneto	Eisemann Model 82D
Cylinders	2
B x S	2 1/2” x 2″
HP	16 @ 4000 RPM
Point gap	0.020
Sheer pin	7/32” x 1 1/2“
Oil	2/3 pt SAE40 per gal.
Tank	Sheet aluminum
Exhaust	Under water
Lower unit	Stream lined ball bearing
Rope plate	8″ SeaGull

Model Name: 1933 OB16
Original carburetor	Tillotson MS-47B
Magneto	Eisemann Model 82D
Cylinders	2
B x S
HP	16
Point gap	0.020
Sheer pin
Oil
Tank
Exhaust
Lower unit
Rope plate

Model Name: 1933 OB31 Junior Neptune Twin
Original carburetor	Tillotson MS-45A
Magneto	Eisemann Model 82D
Cylinders	2
B x S	2″ x 1 1/2“
HP	3 @ 2800 RPM
Point gap	0.020
Sheer pin	5/32” x 3/4” or 3/16” x 3/4“
Oil	2/3 pt. SAE-30 per Gal.
Tank	Cast aluminum smooth
Exhaust	Above water
Lower unit	Plain bearing
Rope plate	8″ sand cast Motorgo

Model Name: 1933 OB31A Junior Neptune Twin
Original carburetor	Tillotson MS-45A
Magneto	Eisemann Model 82D
Cylinders	2
B x S	2″ x 1 1/2“
HP	3 @ 2800 RPM
Point gap	0.020
Sheer pin	5/32” x 3/4” or 3/16” x 3/4“
Oil	2/3 pt. SAE-30 per Gal.
Tank	Cast aluminum smooth
Exhaust	Above water
Lower unit	Plain bearing
Rope plate	8″ sand cast Neptune

Model Name: 1933 OB34U Muncie Twin
Original carburetor	Tillotson MS-45A; Superceeded by MS-45D
Magneto	Bosch FY6FD or Eiseman 82D
Cylinders	2
B x S	2″ x 1 1/2“
HP	4
Point gap	0.020
Sheer pin	5/32” x 3/4” or 3/16” x 3/4“
Oil	2/3 pt. SAE-30 per Gal.
Tank	Cast aluminum smooth
Exhaust	Under water
Lower unit	Plain bearing
Rope plate	8″ sand cast Muncie

Model Name: 1933 OB4 Motorgo
Original carburetor	Tillotson MS-45A; Superceeded by MS-45D
Magneto	Bosch FY6FD or Eiseman 82D
Cylinders	2
B x S	2″ x 1 1/2“
HP	4
Point gap	0.020
Sheer pin	5/32” x 3/4” or 3/16” x 3/4“
Oil	2/3 pt. SAE-30 per Gal.
Tank	Sheet metal
Exhaust	Under water
Lower unit	Plain bearing
Rope plate	6″ Motorgo

Model Name: 1933 OB4A Improved Twin
Original carburetor	Tillotson MS-45A; Superceeded by MS-45D
Magneto	Bosch FY6FD or Eiseman 82D
Cylinders	2
B x S	2″ x 1 1/2“
HP	5 @ 3200 RPM
Point gap	0.020
Sheer pin	5/32” x 3/4” or 3/16” x 3/4“
Oil	2/3 pt. SAE-30 per Gal.
Tank	Sheet metal
Exhaust	Under water
Lower unit	Plain bearing
Rope plate	6″ Neptune Twin

Model Name: 1933 OB4B Muncie Twin
Original carburetor	Tillotson MS-45A; Superceeded by MS-45D
Magneto	Bosch FY6FD or Eiseman 82D
Cylinders	2
B x S	2″ x 1 1/2“
HP	4
Point gap	0.020
Sheer pin	5/32” x 3/4” or 3/16” x 3/4“
Oil	2/3 pt. SAE-30 per Gal.
Tank	Sheet metal
Exhaust	Under water
Lower unit	Plain bearing
Rope plate	6″ Muncie

Model Name: 1933 OB4U Motorgo
Original carburetor	Tillotson MS-45A; Superceeded by MS-45D
Magneto	Bosch FY6FD or Eiseman 82D
Cylinders	2
B x S	2″ x 1 1/2“
HP	4
Point gap	0.020
Sheer pin	5/32” x 3/4” or 3/16” x 3/4“
Oil	2/3 pt. SAE-30 per Gal.
Tank	Sheet metal
Exhaust	Under water
Lower unit	Plain bearing
Rope plate	6″ Motorgo

Model Name: 1933 OB51
Original carburetor	Tillotson MS-45A
Magneto	Eisemann Model 82D
Cylinders	2
B x S
HP	6
Point gap	0.020
Sheer pin
Oil
Tank
Exhaust
Lower unit
Rope plate