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Old 05-01-2015, 07:00 AM   #1
Dave Box
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E-Z-GO
 
Join Date: May 2010
Location: Rocky Mount, Virginia
Posts: 2,190
Default 1970 to 1990's Marathon explained - Manual

As Scowboy says it is the 3PG and it generates 11 hp. It also benefits from a more efficient differential. Here is a short history of the engine.

-In 1976 the so-called '2pg'--a 244cc, Fuji Heavy Industries/Robin Engine--with an internal starter generator (st/gen), became standard. Repair parts are still available except for the crankshaft assembly, the voltage regulator/starter relay and the internal st/gen stator & field.

-In 1980, an external, Hitachi brand starter generator was introduced and the engine was modified. The crank bearings, drive clutch, point set & condenser, voltage regulator and the engine frame all changed.

-1981 ushered in an electronic ignition system, which did away with the golf carts point set & condenser altogether, and the point activator lobe on the crankshaft soon went away too. Except for the addition of an oil injection system, this engine went virually unchanged until 1989 when the 3pg golf cart engine replaced it. Although the two engines are similar, many parts are very different.

-1983 was the oddball year for the 2pg engine. The muffler was placed behind the engine and it layed down instead of standing up. The '83 golf cart had a different engine frame, muffler & exhaust stack. It only lasted one year though...lots of problems.

In '84 the E-Z-GO golf cart went back to the old exhaust system & stand-up muffler on the driver side of the car.

1988 was the last full year of the 2pg engine. A larger golf cart carburetor and another change to the muffler & exhaust system were implemented trying to get more power for the car. The st/gen bracket also went through several changes as the incresed power caused the original bracket to break apart.

In mid-year 1989, (early '89 models had the 2pg engine) E-Z-GO changed to the '3pg' engine, leaving the old 2pg to history. The '3pg' engine has the spark plug turned upward, and the whole engine is rotated such that both clutches face the driver side of the golf cart. This rotation allowed for the differential to be changed from a hypoid gearing to a more efficient helical gear design, a change that persists to this day. The lay-down style golf cart muffler for the '3pg' engine is in front of, and slightly above the engine. The piston is about the only part that works in either engine. The crankshaft & clutches, the exhaust system, the carburetor, air intake & control cables all changed.

1992 is the generally accepted date that the twin-cylider 4-cycle engine became the standard power plant but in fact the 3pg engine can be found in golf carts as late as 1994.
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