D-400 engine
title: "D-400 engine" type: doc version: 1 created: 2026-02-28 author: "Wikipedia contributors" status: active scope: public tags: ["lawn-mowers"] topic_path: "law" source: "https://en.wikipedia.org/wiki/D-400_engine" license: "CC BY-SA 4.0" wikipedia_page_id: 0 wikipedia_revision_id: 0
::data[format=table title="Infobox automobile engine"]
| Field | Value |
|---|---|
| name | D-400 series engine |
| image | Masport Iron Horse Mower.jpg |
| caption | Restored Masport Iron Horse engine |
| manufacturer | Outboard Marine Corporation (OMC) |
| Lawn-Boy | |
| aka | Iron Horse |
| production | 1954--1977 |
| successor | D-600 |
| configuration | Single-cylinder 2-stroke |
| displacement | 108.99 cc |
| bore | 60.325 mm |
| stroke | 38.1 mm |
| block | Aluminum |
| head | Aluminum |
| compression | 4.5:1 |
| fuelsystem | Float carburetor |
| fueltype | Petrol |
| oilsystem | 16:1-32:1 pre-mixed fuel:oil mix |
| coolingsystem | Air-cooled |
| power | 3.5 hp |
| :: |
| name = D-400 series engine | image = Masport Iron Horse Mower.jpg | caption = Restored Masport Iron Horse engine | manufacturer = Outboard Marine Corporation (OMC) Lawn-Boy | aka = Iron Horse | production = 1954--1977 | predecessor = | successor = D-600 | configuration = Single-cylinder 2-stroke | displacement = 108.99 cc | bore = 60.325 mm | stroke = 38.1 mm | block = Aluminum | head = Aluminum | valvetrain = | compression = 4.5:1 | supercharger = | turbocharger = | fuelsystem = Float carburetor | management = | fueltype = Petrol | oilsystem = 16:1-32:1 pre-mixed fuel:oil mix | coolingsystem = Air-cooled | power = 3.5 hp | specpower = | torque = | length = | width = | height = | diameter = | weight =
The D-400 series engine or the Iron Horse engine was a light-duty two-stroke engine used for powering lawnmowers produced from the 1950s to the late 1970s. D-400 engines were single-cylinder engines designed and manufactured by the Outboard Marine Corporation (OMC; Johnson and Evinrude) for Lawn-Boy and Masport. The D-400 engines displaced 109 cc, generated 3.5 hp of power, and operated in the range of 2400-3300 RPM.
Description
The engines have a distinctive rectangular cowling that has created a nickname of brick-top mowers. Another distinctive feature is the two-finger vertical recoil starter. The kidney-shaped muffler and exhaust unit is mounted beneath the mowers' deck and gives the engine a small, low profile design when compared to the newer and more powerful lawnmower engines. The ignition system employs a magneto, points, and a condenser (capacitor) set-up with an unusual spark-advance system which utilised a weight on the crankshaft to adjust the spark-advance amount depending on engine speed. The sprung governor was also unusual with a throw-yoke which operated under the flywheel and was linked to the throttle. The carburetor was a float design and fed into a pair of reed valves.
In New Zealand and Australia, Masport also known in New Zealand as "Charlie Gamble" offered the D-400 engine on their Premier, Premier II, Rancher, Rotacut, and Tornado models. In this Oceania market, the D-400 was called the Iron Horse engine.
References
References
- Lawn-Boy. (1983). "Lawn-Boy Service Manual 1950--1983".
- (2012). "Lawn-Boy brand history".
- (2008). "Lawn Boy Engine series".
- (2011). "Moving Up to Masport TV {{sic".
::callout[type=info title="Wikipedia Source"] This article was imported from Wikipedia and is available under the Creative Commons Attribution-ShareAlike 4.0 License. Content has been adapted to SurfDoc format. Original contributors can be found on the article history page. ::