1986 ezgo2pg running problem

[toadh21]

I rebuilt this motor and it keeps backfiring and blowing the front seal out. I dont know very much about these motors. Somebody told me maybe the forward and reverse switch may be backwords. Need some ideas thanks

[financethis]

I am sure the backfire has to do with the timing. It needs a retardation or advance in timing to stop the backfir

[Dave Box]

During the last 26 years the mating surface of the seal has become worn and is now no longer a tight interference fit. The solution is to use some Loctite blue thread seal on the mating surfaces and that will hold the seal in place.

This of course addresses the symptoms and not the disease, which is the backfiring. The most common form of backfire with the 2PG engine is on hitting the throttle after coasting on the flat or downhill. Is this the case with you or does your engine just randomly backfire under all driving conditions? Answer that and we will be on the way to fixing your cart.

Dave

[toadh21]

Yes mine only backfires after i have been coasting

[Dave Box]

What is happening is that when you back off the throttle fuel is still being sucked into the engine although the plug has stopped firing. This means that unburnt fuel collects in the cylinder and is ejected into the exhaust pipe. As the pipe at this point is positioned downwards the fuel just sits there. When you press the throttle again the plug fires and ignites the fuel in the cylinder. The design of the 2 stroke is that the exhaust port opens during the power stroke which exposes the collected fuel in the exhaust pipe to a flame which causes the backfire. This extra pressure runs back through the cylinder through the inlet port where is pressurizes the crankcase and causes the seal to pop.

You can test this by keeping your foot on the throttle slightly during your next downhill run (you may have to brake with your left foot). By keeping the spark plug firing you will not observe any backfiring.

Rectifying this problem requires adjustment of the carburetor butterfly and the throttle microswitch. The first thing to check is that there is a spring on the throttle cable by the butterfly arm. Although this is primary there to allow the governor to work it also applies extra pressure to keep the butterfly closed. If that is there then remove the air pipe and look into the air intake to make sure the butterfly is closed completely. If you are happy with that then you will need to adjust the relationship between the butterfly and the throttle microswitch. What you are aiming to do is, when you lift off, have the butterfly closed before the microswitch opens and stops the plug from firing. This might be as simple as adding some tension to the aforementioned throttle spring.

In any case most people will tell you to Loctite Blue the seal in.

Dave

[redcloud]

I had my carb not shutting all the way and was getting a puffing backfire at times when I went to push the peddle down to go. Found that with age the spring on the throttle braket on top of the carb/throttle shaft was just not giving enough spring back so I took it off and twisted it to make it have to spring harder again and it works great. I have not run the cart much yet but since I did the spring it has not did anything. Also all is adjusted to give me full throttle and back to closed. cart runns better than ever now. Just thought I would mention that. My 90 cart is the 3pg.

[toadh21]

What exactly is the throttle microswitch.

[redcloud]

Some times called the limit switch that clicks when you put the gas peddle down. That sends power to the regulator and thus to starter/gen to roll engine and start it. If the switch is bad or needs good contact wires cleaned you can have trouble with spark also. Switch should click when you put 1/2" travel of peddle. Your throttle at carb should not open until the click happens. Adjusting this is a bit of play and see from switch settings and throttle linkage at carb settings. I have been running mine now since I last posted and have had a few very small little puffs but that was my fault as I kept the peddle down a bit and was still rolling. I have not had the consitant puffing since I adjusted the throttle to close all the way and not open until the click of the limit switch is heard. You find these settings a bit troubling as when you get the closing all ok, you find that now it does not open all the way but keep playing until you get all the right settings for both complete shut and complete open throttle.

[toadh21]

Thanks you guys that fixed the problem. I have another question. When i go up just a slight hill it bairly wants to go up it. Is there something. I can adjust or replace or is that just how they are

[Dave Box]

Well assuming that the engine is still sound ..

It is fairly common for the driven clutch to jam in the closed (high gear) position which will cause the cart to struggle up a hill. I would jack up the rear axle and gently rev the engine to observe the operation of the clutches.

Dave