Can someone help me with the rotary spark ignition tester?

[drenchedgremlin]

I am feeling kind of confused at the moment. Trying to test the spark & coil for a briggs that i am trying to get running. I have the rotary spark tester. When i follow the instructions for step #1: "to check plug wire magneto/coil", & turn the engine over, The red light only comes on. There is no note on the instruction paper, of what that indicates. I plug it into my other running bike & try the same thing & it lights up red as well. Maybe i have the lights mixed up or the orange is blinking too but it is just very hard to see?

Secondly, when checking the spark plug, by following step # 2; "to check spark Plug without removing plug from engine", Neither lights go on, which indicates "plug is bad, electrode open". The first time i tested this engine I saw that neither light go on so i replaced the spark plug, but it is still neither lights going on. I am seriously wondering if i just cant see the orange light but it is on. Does anyone else have problems seeing the orange?

Lastly, does anyone know what "electrode open" means?

Pics of the instructions & tester:

For the lights, if someone can confirm: the one on the left is the red & light on the right is orange.

 

[noseoil]

I usually just take out the plug & lay it on the block. Give the starter a pull & see if the plug makes a spark. If it does, the only thing to check is fuel (carb, if it already has enough compression, oil, valves & everything else is working properly). I know this is crude, but if it gets spark & the right amount of fuel, it has to start & run right.

 

[drenchedgremlin]

I usually just take out the plug & lay it on the block. Give the starter a pull & see if the plug makes a spark. If it does, the only thing to check is fuel (carb, if it already has enough compression, oil, valves & everything else is working properly). I know this is crude, but if it gets spark & the right amount of fuel, it has to start & run right.

Hey, thanks for your reply. SO if i understand correctly you don't need a tester to check for spark? I have tried what you mentioned & i am not seeing any spark. Where would the spark be visible from? I put the plug up against bare metal on the block & do not see spark from anywhere on the plug. However, when holding the sides of the plug wire (where plug connects), i can feel it lightly shock my finger. What do you think this would indicate?

 

[noseoil]

If it's an older motor, it could be just bad insulation which is grounding the current before it gets down the wire to the plug. If you feel it as a tingle, it's doing something.

Normally, you should see the spark at the tip of the electrode jumping across the air gap. If the gap is adjusted too big, it might not get across. You can check the plug for about a .025"-.030" gap & see what you have. If the gap is too big, it can't jump across the distance. If the insulator is cracked internally, it can be grounding inside the plug itself & you won't see it happen. You can always put your finger in the plug wire & pull the rope to see if you feel anything....

 

[drenchedgremlin]

If it's an older motor, it could be just bad insulation which is grounding the current before it gets down the wire to the plug. If you feel it as a tingle, it's doing something.

Normally, you should see the spark at the tip of the electrode jumping across the air gap. If the gap is adjusted too big, it might not get across. You can check the plug for about a .025"-.030" gap & see what you have. If the gap is too big, it can't jump across the distance. If the insulator is cracked internally, it can be grounding inside the plug itself & you won't see it happen. You can always put your finger in the plug wire & pull the rope to see if you feel anything....

Okay, yes it is an older motor. I have just checked the gap, it is correct so ruled that out. The plug is brand new & the old plug doesnt show a spark either. Can a new plug come with a cracked insulator? And what did you mean exactly by bad insulation? Is that in the coil or still talking about the plug?
I just tried it with 3 different plugs, so really wondering if i just need a new coil. Confusing since i know at least 2 of the plugs should work

 

[ole4]

Does this motor have a magneto mounted under the flywheel or the later external coil on the outside of the flywheel?

 

[drenchedgremlin]

View attachment 98392 View attachment 98393

Just in case, I think something funky may be going on with the wiring that could be causing this issue. it feels like the coil works when i touch the wire and pull the starter. But when i compare it to other engines i have it feels fairly weak. So maybe its just not enough spark to see it

 

[drenchedgremlin]

Does this motor have a magneto mounted under the flywheel or the later external coil on the outside of the flywheel?

Have just posted pics

 

[drenchedgremlin]

Heres the pics, not sure if can see in last post.

Again if anyone knows what would cause spark to not get through the plug, please let me know. The plug works (shows spark when tested with other motors), The coil shocks my fingers when i test it out. Wondering if its the wiring, or if its just flat out a weak coil

 

[noseoil]

I would clean up the rust (sand it off the surfaces) from the flywheel & coil both. Then reset the gap & see what you have. It could be all of that oxidation causing too much resistance, a bad gap & corrosion. The plug wire itself could have small cracks in the insulation. Have you tried turning the crank at night in the dark, to see if there are any stray sparks showing up where they shouldn't be? If it's insulation, some electrical tape might fix it...

I would also think about maybe looking into a HF Predator motor swap. For $100 it might be easier in the long run than spending too much time & trouble on the old motor. You might also find something useful on craigslist that would be OK to use & fit the frame.

 

[ole4]

That is an external CDI It should not have wiring other than a tab on it connected to the kill switch. When you ground the tab it gets shut off. If the gap is correct then just replace the CDI unit, they do go bad.

 

[Havasu Dave]

A word on magnetos and flywheels and rust. The presence of normal rust does not impede "spark." The system works on induction, not electrical continuity. Many of the small engine manuals actually address this.

The points however are a different story, and are quickly affected by higher resistance.

The reason for using a spark tester is because the spark acts differently under compression, than it does with a spark plug sitting on an engine. You can have a good spark on a plug sitting out of the bore and grounded, yet have a weak magneto, insufficient for firing the plug under pressure.

From your description, it seems to indicate you have either a bad magneto, or a bad plug wire. "Electrode Open" means that the electrode on your plug is not electrically connected to the stud on top of the plug. I've never seen this. Double check your connections on the tester, and definitely compare a known engine with the troubled engine.

You should also specify in this post which type of ignition system you are using, points, or magnetron (solid state). Note that these engines will generate an adequate spark at a magneto gap from .010 to .040 roughly, even covered in rust. You have a bad magneto, a bad wire, or points are malfunctioning.

 

[drenchedgremlin]

A word on magnetos and flywheels and rust. The presence of normal rust does not impede "spark." The system works on induction, not electrical continuity. Many of the small engine manuals actually address this.

The points however are a different story, and are quickly affected by higher resistance.

The reason for using a spark tester is because the spark acts differently under compression, than it does with a spark plug sitting on an engine. You can have a good spark on a plug sitting out of the bore and grounded, yet have a weak magneto, insufficient for firing the plug under pressure.

From your description, it seems to indicate you have either a bad magneto, or a bad plug wire. "Electrode Open" means that the electrode on your plug is not electrically connected to the stud on top of the plug. I've never seen this. Double check your connections on the tester, and definitely compare a known engine with the troubled engine.

You should also specify in this post which type of ignition system you are using, points, or magnetron (solid state). Note that these engines will generate an adequate spark at a magneto gap from .010 to .040 roughly, even covered in rust. You have a bad magneto, a bad wire, or points are malfunctioning.

I will double check my tester soon even though I already did more than once. I know nothing is wrong with the plug when I tested it on other motors as well. So I guess I should buy a new coil. I may be wrong, but if I buy a new coil, would this fix my magneto or wire problem, if that is what the problem is?

 

[ole4]

You dont have a magneto! Your picture shows external cdi. No points just a ground tab like I posted above.

 

[DeadPixel]

Does this motor have an internal low oil switch?

 

[drenchedgremlin]

Does this motor have an internal low oil switch?

Not sure exactly, how would I tell?

 

[DeadPixel]

There will be a wire coming out of the block for it. It is connected to your ignition system and shuts it down if the oil level is too low. I have had my mower cut out and seam like it was missing due to low oil. I am sure if the switch was bad it could cause problems that looked like an ignition issue. I believe you can just disconnect it.

 

[drenchedgremlin]

There will be a wire coming out of the block for it. It is connected to your ignition system and shuts it down if the oil level is too low. I have had my mower cut out and seam like it was missing due to low oil. I am sure if the switch was bad it could cause problems that looked like an ignition issue. I believe you can just disconnect it.

There is a wire coming from the block. I changed oil to proper level so i know it is not low. If i disconnect (clip the wire completely off), can i bypass the sensor completely? just making sure i understand correctly. Thank you!

 

[DeadPixel]

No it dose not effect the governor operation. Don't clip it off, just disconnect it. Make sure your motor still runs before cutting stuff out to make sure its the right wire. Run motor and shut it off with wire disconnected just to be safe. And just to be clear your talking about an electrical wire right? Honestly you don't have to cut wire out. Low oil switch just needs disconnected to be bypassed.