90 Marathon Throttle,Gov. question.

[mallard man]

I have a 90 Marathon that I did a complete engine rebuild on last summer. Runs great except that at slower speeds the engine wants to cut off, when I give it more throttle it wants to go too fast. I have read service manual and adjusted governor linkage and micro switch several times and still the same thing. Any ideas?

[fastwoman]

I hope you get an answer, because I have the same cart and same issue.

I think it's just the nature of the beast. We're getting in the habit of "stomp and go" driving. I haven't experimented much with throttle/governor adjustments yet, but I think it's pretty close to correct on mine. I have a new carb and did some basic adjustments.

If we ultimately decide it's too jerky a way to drive, we might mod the ignition circuit to keep the engine running when our foot comes off the gas. We'll need to adjust the carb idle screw accordingly, of course. It's not as simple as wiring alternative power to the ignition circuit. You also have to consider the generator output at idle, which I think is insufficient to charge the battery; thus, you'll have the starter/generator dragging the motor at the cost of battery power. You can mitigate some of this drain by dropping out the starter/generator connection when your foot comes off the gas. Your ignition will still be running off of battery, though. Then you also need a convenient way to kill the engine before reversing it.

I've also wondered about our rickety throttle linkage. The linkage where the governor shaft exits the differential is quite wobbly due to a worn bushing. Perhaps I can make a new bushing. The oiler and its linkage have long since been removed. One possible work-around might be to cobble up a new throttle cable system, bypassing the governor and running directly to the carb.

[cart around]

Are these 3 PG 2 cycle engines? The 2 PG engines have carburetors that are spring loaded open. The throttle cable holds them closed.

On the end of the throttle cable, there is a spring that gives a little cushion while making sure the throttle is completely closed to prevent backfiring. It also makes the throttle more responsive, and not so jerky.
I'm wondering if yours is supposed to be set up the same way.

[BrewCityMusic]

it's a common issue with the 2-strokes, and an easy fix - You need to adjust your linkage so that the pedal microswitch clicks *just before* the throttle starts to open (it's best done using your ears and eyes as versus following the factory manual) - with the key off, take the seat off and watch the throttle at the carb as You push the pedal with your hand - you should feel the "click" of the microswitch before there is ANY movement of the throttle itself. Also, there should be a spring between the throttle arm and the cable stop (it's a small one, not unlike the spring from a pen) - if this is missing, it will not allow the throttle to fully close and you will end up with jerky performance taking off, backfiring, etc. In a pinch you can actually USE a pen spring, but it's best to hit the hardware store and spend $1 to get one slightly stiffer.

[cart around]

These are pictures of the spring we are talking about in the open, and closed position.

[BrewCityMusic]

Thanks, Amigo - I don't have a 2-stroke cart handy and it'd take me like an hour to find my pic of this from past threads on Photobucket, LOL ...

[redcloud]

Good rule of thumb is you should hear the limit switch click with 1/2" pedal travel and that is when the throttle should start to open.