Only running on half the cylinders?

[wyo307]

Hello everyone,

Last night I was able to get my 4378 zephyr to fire up for the first time. It seems like it was only running on half of the cylinders though. How do I go about checking this to make sure? I have a spark plug tester but it wont work with this motor because of the connectors are the screw on type not the push on. Is there a way to check the coils with just a multimeter? Also I am having trouble adjusting the points because of where they are located. Does anyone have any tips for adjusting these? I can’t seem to be able to get my gauge in there to set them. I am hoping that I can just pull the points out and clean them and get it to work but I am not sure. It was firing up and would run for a minute and then sputter out I know I still have some adjusting to do on the carb but it should still run better than it is right now.

Thanks in advance for the help.

[fishingnuts]

I use a piece of copper wire wrapped on the plug to the tester, works to check the spark. Has carb been completely cleaned? And the compression checked. 2 cycle needs compression, spark and fuel to run.
I had one only running on one cylinder and it ended up being a piece of foam that was sucked into the reed valve. Not sure where is came from.

[Tom]

Easiest way to see which plugs are firing is to run it a bit, then see which ones are hot. If it’s running on only two cylinders, it’s likely either the top two or the bottom two.

If you decide to check the coils, remember that you have to test across the two top plug wires to test that coil, then across the two bottom plug wires to test the other one.

Tom

[cajuncook1]

quote Wyo307:

Hello everyone,

Last night I was able to get my 4378 zephyr to fire up for the first time. It seems like it was only running on half of the cylinders though. How do I go about checking this to make sure? I have a spark plug tester but it wont work with this motor because of the connectors are the screw on type not the push on. Is there a way to check the coils with just a multimeter? Also I am having trouble adjusting the points because of where they are located. Does anyone have any tips for adjusting these? I can’t seem to be able to get my gauge in there to set them. I am hoping that I can just pull the points out and clean them and get it to work but I am not sure. It was firing up and would run for a minute and then sputter out I know I still have some adjusting to do on the carb but it should still run better than it is right now.

Thanks in advance for the help.

Some spark checkers have the ability to unscrew the plug attached end. This allows you to attach spark checker to wires that have an eyelet end. Then you just re-screw the end to secure the plug wire.

[wyo307]

quote fishingnuts:

I use a piece of copper wire wrapped on the plug to the tester, works to check the spark. Has carb been completely cleaned? And the compression checked. 2 cycle needs compression, spark and fuel to run.
I had one only running on one cylinder and it ended up being a piece of foam that was sucked into the reed valve. Not sure where is came from.

The Carb has been completely cleaned along with the tank and the gas line. I don’t have a compression tester but by visually inspecting the pistons and cranking the motor over it seems to have no issues there. I believe that it is a spark issue not a fuel or compression issue. I may have a small blockage in the low fuel hole but it should still run on the high end alone.

[Mumbles]

Since two cylinders fire at the same time on these motors and use the same ungrounded coil, both plug wires for these cylinders have to be connected in the circuit to check for spark on either cylinder.

When the plugs fire, either the top or bottom cylinders together, the spark travels out of one terminal on the coil, down the wire to the plug, across its electrodes to ground firing the plug, through the motors block to the other plugs electrodes and back to the coil completing the circuit. If either plug wire is undone or faulty, neither cylinder will get spark.

Here’s a short video showing how I checked for spark on a Zephyr. The ends of the wires were cut flush with just a bit of the core wire sticking out and I taped them together before spinning the motor over with a drill. You can see how the spark always jumps across the same two wires. This motor has great spark!

https://www.youtube.com/watch?v=4VD_0xOBLFw

[fishingnuts]

Tom Manley, I’m a bit confused, I thought we were talking about a two stroke two cylinder outboard, is this one a 4 cylinder??

[Casey Lynn]

Yep….World’s smallest production 4-cylinder outboard at 5.4hp.

[Mumbles]

quote Pappy:

Yep….World’s smallest production 4-cylinder outboard at 5.4hp.

Maybe one of the fastest 5 plus horse motors to.

Like they say ‘Dynamite Comes In Small Packages!’ 😀

[ray-schaber]

With the motor running short out each plug with a screwdriver if no change in rpm that cylinder is not working. Check all four.
Ray

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