Ezgo fouling one spark plug

[ewsisk1s]

Have a workhorse with the 350. The engine has an MCI head with pre MCI parts, some one mashed some stuff together. The cart is continuously fouling the driver side spark plug, it is always wet. I have checked spark and both plugs show great spark firing at the same time. I have replaced multiple spark plugs. I have replaced valve stem seals. I tried a new ignition coil just in case. I installed a new carburetor straight from ezgo. I have checked compression multiple times and it always comes back at 160/165 each cylinder. I have adjusted the valves multiple times to 0.004 inches. I have drained the oil and added a little less than 1.5 quarts. The engine runs great, cart does not hesitate, just fouls plugs and smokes

The cart does have some moisture showing inside the air intake (maybe just condensation but seems excessive), smells like maybe some gas as well, see pictures. The driver side spark plug is fouling and when removing the plugs while the engine was still warm there was smoke coming out of the driver side spark plug hole. Also smoke coming out of the valve cover after removing that while still warm. There is also a slight gas smell coming from the oil after changing it. You can smell a little gas smell coming from the dip stick as well. And when adjusting the valves you can smell gas.

Any ideas? I was told to check timing and will look at that but I am thinking it might have a bad oil ring on the drivers side. Any way to check this? Also could this be the head gasket leaking through?

[CP241]

Originally Posted by ewsisk1s

Have a workhorse with the 350. The engine has an MCI head with pre MCI parts, some one mashed some stuff together.

Wait up a minute… this is new information. How many pages of the last post trying to diagnose and just now you’re coming out with this?

You said multiple times it was a mci engine. But it has pre-mci “parts”???

You need to be more specific here about exactly what you have here. Is the bottom half of the engine also mci or is that mixed with pre mci stuff as well? Exactly WHAT all parts are mci or pre-mci?

[ewsisk1s]

Sorry for the confusion. I received the cart this way. I did mention that in the last post though, see the attachment, sorry though if that wasn’t clear. The cylinder head and exhaust manifold are cast as one piece. The valve stem seals are from a non MCI cart I was told because they have the screw driver slots in them. The muffler was cut and welded together. Someone one told me this was because they were fitting a pre-MCI muffler to an MCI head so it had to be modified some. The ignition I am not sure. From research it looks like a pre-MCI ignition since this one has the two separate connection for the red and white wire instead of a single connector. The carb is MCI as I ordered it straight from ezgo. When I received the cart it had an Amazon carb. Not sure about anything else yet. The timing cover is silver and the airbox is the cylinder style. Not sure if these mean MCI or pre MCI but I think I remember reading something about them somewhere.

Sorry I don’t know about the bottom half, I am just learning as I go and look up parts what appears to be MCI vs pre MCI in this cart. Assuming someone mashed two carts together at some point but I have only had it for a few weeks.

[cart around]

I was going to post this morning, but changed my mind thinking it wasn't relevant. Now that you have said the muffler was cut, I have to tell you my story.

When I was 19, I bought a 75 Harley Sportster. The first thing I did was install drag tubes because a Harley was supposed to be loud. It wouldn't run right after that. Within a quarter mile the rear plug would foul and then it would start popping and missing. I started chasing ignition issues by changing plugs, wires, and ignition coil. It still wouldn't make it more than that quarter mile. It was always the rear cylinder. Even when swapping wires.

Turns out that when I installed the drag tubes, I should have also rejetted the carburetor. The lower back pressure is what caused all of the problems.

Maybe this is your issue. Maybe not, but it's something to think about.

[trig123]

The Pre Mci muffler will work but I would rather use the MCI because that was part of the upgrade ezgo made in 2004. Someone probably didn't want to pay what for a MCI muffler is why they chopped it to make it fit. The MCI had a little larger and redesigned muffler. That won't cause it to smoke and it should run fine with the pre mci muffler.
The engine is an MCI. The heads won't interchange.
You have two MCI rocker arms on it ( two in the middle ) but they will work fine and you can use either adjustment method.
You can't use the ignition from a pre mci engine on a MCI cart by the way. Yours will have the MCI coil , pulser and coil or it wouldn't run .
Now for why its smoking. My guess you need to rebuild the engine and probably have a bad oil ring but I can only guess from my end. I might also try and find a good used MCI muffler if you do rebuild it. Like I told you in one of the other posts. You can have good compression but that won't tell you anything about the oil ring.
I hope this helps some in the confusion you have about mixing the parts.

[CP241]

Sorry I missed that post.

I think trig or cartmaster may be better equipped to answer this, but I’m pretty sure there was more different in the muffler than just the mounting flange.

The pre mci coil may also be an issue with a mci engine. I know they are different though I have used a MCI coil on a MCI cart, don’t think I’ve Ever tried the other way around. (Though that may be backwards as well, it’s been a while since I rebuilt one of these).

What does the flywheel lol like? What about the ignitor? The mci and pre-mci ignition systems are very different between the 2 carts, and the parts are not interchangeable…

[trig123]

Originally Posted by CP241

Sorry I missed that post.

I think trig or cartmaster may be better equipped to answer this, but I’m pretty sure there was more different in the muffler than just the mounting flange.

The pre mci coil may also be an issue with a mci engine. I know they are different though I have used a MCI coil on a MCI cart, don’t think I’ve Ever tried the other way around. (Though that may be backwards as well, it’s been a while since I rebuilt one of these).

What does the flywheel lol like? What about the ignitor? The mci and pre-mci ignition systems are very different between the 2 carts, and the parts are not interchangeable…

The MCI coil will work on the pre MCI engine. You can't use the pre mci coil on the MCI engine though. I edited my last post so not sure you saw what I posted there CP
I can explain how to smoke a coil also

[CP241]

Originally Posted by trig123

The MCI coil will work on the pre MCI engine. You can't use the pre mci coil on the MCI engine though. I edited my last post so not sure you saw what I posted there CP
I can explain how to smoke a coil also

yes you can

I know I have used one of the coils on the other engine but can’t remember which way I did it. I had a run of auction ezgo’s for a bit there but that was 3 or 4 years ago.

You know how much I love mci engines

[trig123]

Originally Posted by CP241

yes you can

I know I have used one of the coils on the other engine but can’t remember which way I did it. I had a run of auction ezgo’s for a bit there but that was 3 or 4 years ago.

You know how much I love mci engines

I know you can take an MCI engine in and out in a Georgia minute

I also meant to say that one could make a Pre MCI muffler work on an MCI engine , meaning where it would bolt on. I just wouldn't do it because these MCI engines were designed using a larger muffler. Not sure if it would perform at top peak. I've never did it but I do know a few people who have chopped on one to make it work.
The MCI has a complete different ignition. It makes a hotter spark so they crank better. That part does work as you don't even have to choke a MCI engine if the temps are above 60 f.
The pulsers won't interchange either . Neither will the ignitors.
I have both MCI and pre MCI engines still sitting on my homemade table . That way I was able to test for myself what will run with what. I smoked a few coils in my testing as you well remember. My testing station is now closed lol

[trig123]

Originally Posted by cart around

I was going to post this morning, but changed my mind thinking it wasn't relevant. Now that you have said the muffler was cut, I have to tell you my story.

When I was 19, I bought a 75 Harley Sportster. The first thing I did was install drag tubes because a Harley was supposed to be loud. It wouldn't run right after that. Within a quarter mile the rear plug would foul and then it would start popping and missing. I started chasing ignition issues by changing plugs, wires, and ignition coil. It still wouldn't make it more than that quarter mile. It was always the rear cylinder. Even when swapping wires.

Turns out that when I installed the drag tubes, I should have also rejetted the carburetor. The lower back pressure is what caused all of the problems.

Maybe this is your issue. Maybe not, but it's something to think about.

I wouldn't rule out anything just yet even though I don't think that is his problem.