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-   -   1970 to 1990's Marathon explained (http://www.buggiesgonewild.com/gas-ezgo/105501-1970-1990s-marathon-explained.html)

Dave Box 05-01-2015 07:00 AM

1970 to 1990's Marathon explained
 
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.

francesc1 10-13-2015 03:19 PM

Re: 1970 to 1990's Marathon explained
 
great post!
i have a cross between late 79 and early 80
marathon 2pg
it has the external starter generator.
ran great for the longest time.
i bought it from a member in our trailer park who has since passed.
fuel is ok new points filters and spark plug new
carb cleaned pump is pumping
this is the last of its kind in our park
could the seals be bad?

Doody 03-03-2016 06:04 PM

Re: 1970 to 1990's Marathon explained
 
I have a 86 marathon that I'm rebuilding the top end it has the 2pg engine and I'm trying to figure out if it's better to use the two port 3pg piston instead if some one can shine some light on this that would be grate

TomStark 03-05-2016 06:38 PM

Re: 1970 to 1990's Marathon explained
 
Quote:

Originally Posted by Doody (Post 1249253)
I have a 86 marathon that I'm rebuilding the top end it has the 2pg engine and I'm trying to figure out if it's better to use the two port 3pg piston instead if some one can shine some light on this that would be grate

I do not know, but would bet it is best to use the 2pg piston in the 2pg and 3pg piston in the 3pg. No idea if there is any gain to be made by using the 3 in the 2, but willing to bet it is miniscule at best. I think there is a lot more to gain by making sure the port timing is correct for your use, and that the ports are aimed correctly, maybe give a little more compression, etc.
Tom

kip_66 04-26-2016 12:09 PM

Re: 1970 to 1990's Marathon explained
 
Quote:

Originally Posted by Dave Box (Post 1148973)
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.

Dave,
I am hoping you can help me.. I have a 1989 EZGO Marathon. What function has to take place to get the rear end to go in reverse? Mine is a project cart that I am trying to rebuild and it is missing alot of pieces.. There is a little stub on top of the differential, is that the forward reverse mechanism? If not, how does the cart go into reverse?

TomStark 04-26-2016 03:58 PM

Re: 1970 to 1990's Marathon explained
 
Quote:

Originally Posted by kip_66 (Post 1267617)
Dave,
I am hoping you can help me.. I have a 1989 EZGO Marathon. What function has to take place to get the rear end to go in reverse? Mine is a project cart that I am trying to rebuild and it is missing alot of pieces.. There is a little stub on top of the differential, is that the forward reverse mechanism? If not, how does the cart go into reverse?

If you have a 2 stroke, and 89 should be a 3pg 2 stroke, you go in reverse by starting the engine up backwards. Only 4 strokes have any sort of reverse.
Tom

simmons87 06-10-2016 03:49 PM

Re: 1970 to 1990's Marathon explained
 
i have a 80 ezgo 2pg rear axles are shot its the key one looking to replace can anyone help me out

krp 10-09-2016 05:01 PM

Re: 1970 to 1990's Marathon explained
 
I have a 1990 Maraton Freedom with the 3PG engine. The service manual refers to "early" and "late" 1990 models. There are differences in the wiring for "early" and "late" models. This is critical since I have electrical problems. How can I tell if my cart is "early" or "late"?

WVCartMan 11-13-2016 08:44 AM

Re: 1970 to 1990's Marathon explained
 
I have a 1983 2PG, based on what I read above, would it be a good idea to replace the stock carb and exhaust on this cart with the carb and exhaust from a 1988 2PG to get the added horsepower? Or would this create more problems than it's worth?

Thanks

WVCartMan 11-30-2016 09:13 AM

Re: 1970 to 1990's Marathon explained
 
Dave Box,

One more question about my 1983, when you say "It only lasted one year though...lots of problems." for the 1983, what "...lots of problems." are you referring to? Is there something more than the carb/exhaust that I should be looking for?

Thanks for the help


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