
Designed by Steve Andres
 
NOTE: Muncie – Neptune models having a “U” in their model designation had under water exhausts . Example: OB2AU
| Model Name: 1934 OB1 Waterwitch | 
| Original carburetor | 
Tillotson MS-73A | 
| Magneto | 
Eisemann Model 71H | 
| Cylinders | 
1 | 
| B x S | 
2 1/16” x 1 1/2“ | 
| HP | 
2 | 
| Point gap | 
0.020 | 
| Sheer pin | 
5/32” x 1″ | 
| Oil | 
1/2 pt SAE 30 per gallon | 
| Tank | 
 | 
| Exhaust | 
Under water | 
| Lower unit | 
 | 
| Rope plate | 
Waterwitch | 
| Model Name: 1934 OB15 Motorgo | 
| Original carburetor | 
Tillotson MS-47A | 
| Magneto | 
Eisemann Model 82D | 
| Cylinders | 
2 | 
| B x S | 
2 1/2” x 2″ | 
| HP | 
16 | 
| 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 | 
Non stream lined ball bearing | 
| Rope plate | 
Motorgo | 
| Model Name: 1934 OB15A Master | 
| Original carburetor | 
Tillotson MS47A | 
| 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 | 
3/4 pint to gallon | 
| Tank | 
Sheet aluminum | 
| Exhaust | 
Under water | 
| Lower unit | 
Stream lined early | 
| Rope plate | 
8″ Neptune | 
| Model Name: 1934 OB15B Master | 
| Original carburetor | 
Tillotson MS-47A | 
| Magneto | 
Eisemann Model 82D | 
| Cylinders | 
2 | 
| B x S | 
2 1/2” x 2″ | 
| HP | 
16 | 
| Point gap | 
0.020 | 
| Sheer pin | 
7/32” x 1 1/2“ | 
| Oil | 
3/4 pint to gallon | 
| Tank | 
Sheet aluminum | 
| Exhaust | 
Under water | 
| Lower unit | 
Stream lined early | 
| Rope plate | 
8″ Muncie Master | 
| Model Name: 1934 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 SAE 40 per gal. | 
| Tank | 
Sheet aluminum | 
| Exhaust | 
Under water | 
| Lower unit | 
Later non stream lined | 
| Rope plate | 
8″ Seagull | 
| Model Name: 1934 OB16  | 
| Original carburetor | 
Tillotson MS-47A | 
| 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: 1934 OB1A Neptune Single | 
| Original carburetor | 
Tillotson MS-73A | 
| Magneto | 
Eisemann Model 71H | 
| Cylinders | 
1 | 
| B x S | 
2 1/16” x 1 1/2“ | 
| HP | 
2 | 
| Point gap | 
0.020 | 
| Sheer pin | 
5/32” x 1″ | 
| Oil | 
1/2 pt SAE 30 per gallon | 
| Tank | 
 | 
| Exhaust | 
Under water | 
| Lower unit | 
 | 
| Rope plate | 
Neptune | 
| Model Name: 1934 OB31 Waterwitch | 
| Original carburetor | 
Tillotson MS-45A | 
| Magneto | 
Eisemann Model 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 | 
Above water | 
| Lower unit | 
Plain bearing | 
| Rope plate | 
6″ sand cast Neptune or Waterwitch | 
| Model Name: 1934 OB31A Junior Neptune | 
| Original carburetor | 
Tillotson MS-45A | 
| Magneto | 
Eisemann Model 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 | 
Above water | 
| Lower unit | 
Plain bearing | 
| Rope plate | 
6″ sand cast Neptune | 
| Model Name: 1934 OB5 Motorgo ‘5’ | 
| Original carburetor | 
Tillotson MS-45A; Superceeded by MS-45D | 
| Magneto | 
Bosch FY6FD or Eisemann 82D | 
| Cylinders | 
2 | 
| B x S | 
2″ x 1 1/2“ | 
| HP | 
5 | 
| 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 | 
Ball bearing | 
| Rope plate | 
6″ Motorgo | 
| Model Name: 1934 OB51 Improved Twin | 
| Original carburetor | 
Tillotson MS-45A; Superceeded by MS-45D | 
| Magneto | 
Eisemann Model 82D | 
| Cylinders | 
2 | 
| B x S | 
2″ x 1 1/2“ | 
| HP | 
5 | 
| 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 | 
Smaller sheet aluminum | 
| Exhaust | 
Ball bearing | 
| Lower unit | 
Under water | 
| Rope plate | 
6″ sand cast Neptune | 
| Model Name: 1934 OB5U Motorgo ‘5’ | 
| Original carburetor | 
Tillotson MS-45A; Superceeded by MS-45D | 
| Magneto | 
Bosch FY6FD or Eisemann 82D | 
| Cylinders | 
2 | 
| B x S | 
2″ x 1 1/2“ | 
| HP | 
5 | 
| 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 | 
Ball bearing | 
| Rope plate | 
6″ Motorgo | 
| Model Name: 1934 OB61 Improved Twin | 
| Original carburetor | 
Tillotson MS-45A | 
| Magneto | 
Eisemann Model 82D | 
| Cylinders | 
2 | 
| B x S | 
2″ 1/2” x 2″ | 
| HP | 
6 | 
| Point gap | 
0.020 | 
| Sheer pin | 
5/32” x 1″ | 
| Oil | 
2/3 pt SAE 30 per gallon | 
| Tank | 
Sheet aluminum | 
| Exhaust | 
Under water | 
| Lower unit | 
Ball bearing | 
| Rope plate | 
Water Witch | 
| Model Name: 1934 OB61A Improved Twin | 
| Original carburetor | 
Tillotson MS-45A | 
| Magneto | 
Eisemann Model 82D | 
| Cylinders | 
2 | 
| B x S | 
2″ x 1 1/2“ | 
| HP | 
6 | 
| 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 Aluminum | 
| Exhaust | 
Under water | 
| Lower unit | 
Ball bearing | 
| Rope plate | 
8″ Neptune |