Need expert advice on K-161 Magneto ignition - Still NO SPARK

[Sailman 1,291]

I have a K-141 recoil start engine on the 704 I am trying to get running. I had spark initially but then lost it.

I have followed suggested diagnostics and cannot find the problem. Any experts on this engine willing to help me figure this out???

Here is what has been done;

 

1. Removed all wires from the condenser, put tape on the ends, put the flywheel back on to see if I have spark. NO SPARK. What would that indicate?

 

2. I also took the red insulated wire from the coil OFF and just left the wire to switch and wire to points attached to condenser and did a continuity test. NO continuity to ground. Checked chafe on all wires and all are good. This should mean NO SHORT in wires.

Add the coil red wire and I get continuity with ground with points open and with points closed.

 

2. Spark plug wire from magneto to plug is good, with solid connection at magneto.

 

3. Used my multi meter to check resistance on the magneto.

Set at 20K I get 9.22 - 9.25 on secondary. Also indicates spark plug wire is good.

Set at 200 I get .6 - .7 on the primary.

These are the close to the specs I was given. So it would seem the magneto is good? Would it read 0 or a lot higher if magneto was bad? New one is expensive so I want to make sure this one is bad before I spend $$.

 

I am at a loss to figure this out when all seems to be OK.

This is outside my wheel house so....what does it mean so far? Whats next to try to solve this problem?

Thanks in advance.

 

[gwest_ca-(File Mod) 11,043]

Try this but not sure it will work.

Remove the spark plug so you can turn the engine over by hand.

Take the ignition wire off the ignition switch and connect one ohmmeter lead to it and the other lead to a good battery ground.

I think you should see the .6-.7 ohms when the points are open. Should go to 0 ohms when the points are closed. Slowly turn the engine over and see if the opening and closing of the points changes the readings.

Usually with this problem there is oxidation on the point contacts so when they are closed they do not make electrical contact. This results in the primary résistance staying at the .6-.7 ohms.

[Sailman 1,291]

10 hours ago, gwest_ca said:

Try this but not sure it will work.

Remove the spark plug so you can turn the engine over by hand.

Take the ignition wire off the ignition switch and connect one ohmmeter lead to it and the other lead to a good battery ground.

I think you should see the .6-.7 ohms when the points are open. Should go to 0 ohms when the points are closed. Slowly turn the engine over and see if the opening and closing of the points changes the readings.

Usually with this problem there is oxidation on the point contacts so when they are closed they do not make electrical contact. This results in the primary résistance staying at the .6-.7 ohms.

 

I tried the suggestion above. With it hooked up as stated with a battery I got no reading, just a 1 on the multi meter. If I touch the ground lead to the bearing plate on the motor and NOT the ground on the battery I get a .6 - .7 reading.

Just want to confirm I also installed new set of points and spark plug.

 

Guess I have stumped the folks here on wheel horse...not getting any other solutions...

[gwest_ca-(File Mod) 11,043]

30 minutes ago, Sailman said:

 

I tried the suggestion above. With it hooked up as stated with a battery I got no reading, just a 1 on the multi meter.

 

If I touch the ground lead to the bearing plate on the motor and NOT the ground on the battery I get a .6 - .7 reading.

That indicates the engine is not grounded to the battery but that is not necessary for the above test. By disconnecting the ignition wire at the switch and testing that wire you are using the batteries in the tester. Now connect the other test lead to the bearing plate instead of the battery.

 

Just want to confirm I also installed new set of points and spark plug.

New point contacts should be filed and cleaned to make sure they are completing the circuit when closed. A nail file will work. You must get the resistance to cycle between the .6 ohms and 0 ohms consistent  with the point  opening (.6) and closing (0) as the crankshaft turns. This on/off cycling is what causes the coil to fire the plug.

 

What I don't know is how the condenser will affect the readings because the battery in the tester will charge the condenser. Would be best to disconnect the condenser for this testing.

 

Quote

Guess I have stumped the folks here on wheel horse...not getting any other solutions...

 

[8ntruck 7,004]

In a magneto system, the battery does not play any part in generating the spark.  The magneto coils and flywheel magnets do that.

 

To me, the engine block should be your reference ground for troubleshooting the system.

 

When the primary side of the coil is open (broken winding) or connected to ground, no spark will be generated. 

 

The possibilities of connecting to ground are 1) through the ignition switch, 2) through the points, 3) through the condenser - if it has failed, 4) through a shorted wire to the points or ignition switch.  With the testing you have done, I think that the wiring to the points and switch can be ruled out.

 

Do the test that @gwest_ca described again, but this time use the bearing plate as the ground.  You should see the resistance change as the points open to read the .6 to .7 ohms that you measured across the primary side of the coil.

 

The no spark with the coil disconnected suggests an internal problem in the mag.  The confusing thing is a proper resistance reading on the primary suggesting that it is OK.

 

This is a long shot, but going with the check all the grounds on an old machine with electrical problems theory, have you taken the mag off of the engine and checked for corrosion between the block and the bracket?  Not sure if this would be a problem or not, but we seem to be running out of ideas.

[squonk 41,111]

When a wire (magneto primary wiring) cuts thru a magnetic field (flywheel magnets) rotating a voltage is induced in the wire. It's the law. a magneto is pretty simple. It either works or doesn't. The points only really time when the spark happens. (timing) The condenser cleans up the voltage thru the points. 

 

Seems to me with the magneto coil bolted to the engine with everything else unhooked the coil primary and secondary winding should have no continuity with the block at all. You should be able to bolt on the flywheel and spin it and at least get a weak spark. If you don't, I think the magneto coil is ready for the dust bin. It's 60 years old! 

[Sailman 1,291]

Just an extra note...with the positive lead from my multi tester connected to the ignition wire (disconnected from the toggle switch) I get the .6 - .7 with the negative lead grounded to the bearing plate with points open AND closed. When I spin the flywheel the meter jumps all over the place with multiple readings and  even some negative. When it stops I get the .6-.7. Does that help indicate anything? Thanks!

Edited July 11 by Sailman

[gwest_ca-(File Mod) 11,043]

Don't spin the engine over. Just turn it slow in the normal direction as the points are not open for very long so your tester will miss it.

You have to get the 0 ohms with the points closed. or it will not run.

[Sailman 1,291]

4 hours ago, gwest_ca said:

Don't spin the engine over. Just turn it slow in the normal direction as the points are not open for very long so your tester will miss it.

You have to get the 0 ohms with the points closed. or it will not run.

 I am not spinning it fast, just slowly by hand and watching points open and close. I do NOT get 0 at any time. With points closed I still get the .6 - .7, same as when points open. What would that indicate as the problem?

I just saw the note to disconnect the condenser. Will try that and test again.

OK I just went and disconnected the condenser and I get NO readings either open or closed.

Edited July 11 by Sailman

[squonk 41,111]

Clean the points contacts again. Make sure they are actually closing. Without continuity closed, the primary coil can't collapse inducing the high voltage spark

[Sailman 1,291]

I just cleaned the "new" points again with 400 emery. Pulling a white paper through them there was plenty of drag so I am certain they are closing. Getting .6 -.7 with points open. Starts at .6 and drops to .3 with points closed.

What does this mean??

Bad magneto? Bad condenser?

[oliver2-44 9,750]

As your aware you should get 0 when the points close. 
connect you meter to each side of the points. With the points open you should read infinity and with the points closed good ground. If you don't read a good ground remove the points and clean the mounting area and the screw.  

[gwest_ca-(File Mod) 11,043]

The ignition wire that goes to the switch also goes to the points. 

With the points open the circuit goes through the primary coil windings and that is where you get the .6 ohms. If it was shorted to ground you would get 0 ohms and never see the .6 ohms.

When the points close they are connecting the ignition wire from the switch to the backing plate resulting in 0 resistance if the point contacts are clean.

Try one test lead on the backing plate and the other on the point arm. With the points closed you should have 0 ohms.

[Sailman 1,291]

I guess I am not making myself clear. I cannot get 0 with points closed. I get a reading between .03 and .06. with the points closed. What would cause that? That is my problem. I understand it needs to be .0 to run...but mine does not, I am getting resistance with points closed. Points are clean, well connected, etc. What part is not working that would cause resistance with points closed? Condenser? Magneto?

There is no short in the wiring. from ignition to points. That option has been eliminated.

Edited July 12 by Sailman

[gwest_ca-(File Mod) 11,043]

Does your meter give a 0 reading when the leads are touched together?

Remove the points and test them alone on the bench. Perhaps they won't close on the engine.

[squonk 41,111]

Clip a jumper wire from the points body to the backing plate. Then see if you get 0 ohms when testing the points body to the plate. If you get 0 the points aren't grounded to the plate well enough. 

[Handy Don 12,225]

2 hours ago, squonk said:

the points aren't grounded to the plate well enough. 

Yep, I’d guess it isn’t the points themselves--it’s something else in the circuit that is adding resistance.

[rmaynard 15,459]

I have found that the use of a digital meter when checking points may be confusing. I use an analog meter.

 

Also, no one has mentioned that your air gap appears way too wide.

 

 

Should be 0.008 - 0.012. The low end (0.008) would be the thickness of about two sheets of copy paper.

 

 

[953 nut 55,228]

On 7/11/2024 at 2:24 PM, Sailman said:

When I spin the flywheel the meter jumps all over the place with multiple readings and  even some negative

Meter is too close to the magnets on the rotating flywheel.

21 hours ago, Sailman said:

disconnected the condenser and I get NO readings either open or closed

Best to check each component by itself without anything else connected to it. Use the videos I attached to your other post to check the Magneto coil then use the other video to check the condenser.

 

[Sailman 1,291]

Thanks for all the suggestions. Gotta step away from it for a few days....makes my head hurt when I can't solve a problem. .

 

[8ntruck 7,004]

Not getting 0 ohms with the points closed suggests that the points don't have a good ground or that the wire from the mag to the points is not connected or maybe broken.

 

With the points open, it seems like you should see .6 ohms when checking resistance from the connection between the mag wire to the points and ground - provided that the wire to the ignition switch is disconnected.

 

Good luck.  Old wiring can be challenging to troubleshoot, so keep at it.

 

Edited July 13 by 8ntruck

[Sailman 1,291]

I have gone through every possible link in the K-161 I have. Wires are not grounded, installed new points and new condenser so only other option must be magneto. I get a constant ground at the points and condenser connections.

I do get an erratic small spark occasionally after installing new condenser, not once every revolution of the flywheel.

Sound like magneto grounding out?

[Crossbow 0]

Hello Sailman, I was just wondering if you ever solved your ignition spark problem. I have the same issue. I have and old K161T 7hp Kohler. It was running and I used it a bit. I idled it down, it purred nice, and then it just shut right down. No popping or sputtering, it just died on the spot. I tried to start it again with the recoil and no spark. I put a new magneto coil, points and condenser in it after I cleaned and sanded everything down for good grounding and still no spark. I did all of the electrical test which were ok and still nothing. I am stumped as well. I worked on a few engines so I am familiar with them. My final thought was maybe the magnets on the flywheel were not strong enough. I too had to step away for a few days. It is like the system is grounding itself out somewhere. I checked and rechecked , then checked again and still nothing. I made sure the timing marks were lined up on the flywheel and the plate the magneto is attached to but still nothing. Today I might go out and see if my timing marks on my cam and gears have jumped a tooth. I think I can see that through my inspection hole after I take the cover to it off. Right now I am not sure what to do. I hope you got yours running and if you did could you share what you did to get it running.