K91

[KEN NABER 28]

Fellow Members

Electricity is not my forte. With points closed I test for continuity and have continuity. With points open I still have continuity this should not be?

Ken

[rmaynard 15,418]

Continuity from where to where?

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[KEN NABER 28]

from the engine block to the coil wire screw on the points, all wires connected

Edited November 20, 2012 by KEN NABER

[buckrancher 2,679]

unhook the coil wire from the points you are grounding thru the coil this is normal

Brian

Edited November 20, 2012 by buckrancher

[KEN NABER 28]

Time to show what i do not know, I thought the points opening opened the circut magically forcing the condenser to collect the charge until it reaches the point of accumulation then an arc jumps the spark plug gap and it cycles again. so if points are open it seemed to me then no continunity is possible. remember I told you electricity is not my suit.

[Cole 25]

what he is saying is that the coil grounds the points, if you disconnect the points wire from the coil, With the points open, you should not have continuity. If you do have continuity, then you have to adjust the points so that the have a larger gap. Hope this helps :)

[KEN NABER 28]

that was understood, I thought that with the points open disconnecting the primary side from ground which causes the secondary side of the coil to get excited for some reason the charge of which finds it way to be stored in condenser to a point of over accumulation at which time the spark jumps the gap in the spark plug. Why then would the primary side still be grounded with points open. sorry for my confusion, sooner or later going to figure this out.

[KEN NABER 28]

The points are a switch that when opened cause the ignition coil to fire the spark plug. This only happens if the "points", the smooth contact pads that touch together, are clean as to make a good connection when closed. There is a cam, that turns with the engine, that opens the points just before the piston gets to top dead center. When the points crack open, the spark plug will fire. The ignition coil gets power from the " charge " coil. mounted under the flywheel. As the engine turns over, the flywheel magnet produces electricity with the charge coil.

One end of the charge coil must be grounded. Some are grounded through a tail lamp bulb, if bulb burns out there is no spark. Most are grounded directly to the stator "point" plate. From the other end of the charge coil, power goes to the ignition coil, points, and condenser.

The condenser must be grounded. The other end of the ignition coil must be grounded. The spark plug lead comes off the ignition coil and goes to the spark plug, the spark plug also must be grounded.

If you have battery ignition, then when the ignition switch is on you have power to the points even though the engine is not turning over. You can open the points with a screwdriver, they will spark the spark plug every time you open them.

[TT-(Moderator) 1,131]

Not the most elaborate definition, but a magneto ignition system gets power from a magnet that passes a laminated open armature onto which is mounted an insulated coil of wire surrounding another coil of wire.

The primary winding is "several" turns of heavy wire and is connected to the spark plug. The secondary winding surrounds the primary wiring and consists of many turns of smaller wire. Windings are fully insulated and do not touch each other.

When the magnet passes the armature, the secondary winding is charged with electricity, producing a magnetic field.

Breaker points or some other type of timed switch break the circuit of the secondary windings, causing the magnetic field to collapse. The collapse of the magnetic field produces high voltage in the primary windings - which fires the spark plug.

The condenser is a capacitor and is there to absorb the residual electricity that 'burps' back through the secondary windings when the primary windings discharge. Since the points are open at that time, they will arc and prematurely burn without the condenser present.

If you follow the circuit path from the points back to the secondary winding of the coil, you would find the other end of the windings are grounded. That is why you see continuity to ground at the points even if they are open. If you don't have continuity, the coil winding is 'open' - which normally means the coil is bad.

Older battery ignitions work on the same principal - except that a battery is used to energize the ignition coil instead of magnets.

[Cole 25]

Glad you understand :handgestures-thumbupright:

[KEN NABER 28]

well back to it, thanksgiving is over. played with the ignition today, new points, new condenser, new coil, new spark plug wire, all connected as before. points set with matchbook they are new and open apparently at the right time as required. magnets in flywheel attract screwdriver so they appear to be ok. hook wires to my new spark tester grounded via aligator clip and adjusted to gap of plug. with spark plug out take my drill and spin engine at fairly fast pace and still no spark. I will figure this out, am sure someone will enlighten me.

I have also tested for continuity at points with coil wire unattached have continuity closed and not so when open. also the wire coming from coil has continuity and no continuity with block when disconnected from coil and points. i also have good ground at stator and coil wing thing all have continuity with block.the winding in coil that connects to points has continuity through the coil wire to other wire, ohms test on the 2 wires coming out of coil that one connects to stator for ground and one to points for spark, my multi meter shows .7 ohms with meter set on 200. i assume this indicates small resistence so it passes that test. how does one test the coils winding that goes to spark plug, i am thinking that this is not connected to the other coil winding that connects to points.

I take my multi meter touch one probe to the other and with meter set on continuity beep setting it reads 002 with no point indicating decimal, when I touch one probe to point wire and touch spark plug side of coil i read 1850, i assume that indicates the step up in volts would it be? i also get similar readings, 1650, on old coil so it might be good. i am not sure if this passes a test

have i eliminated or found the problem, is it the magnets?

I understand http://magneto-repair.com/ rebuilds magnetos (recharges magnets) how do you evaluate the magnets?

i apologize about my novice level abundently present in this post

Edited November 26, 2012 by KEN NABER

[KEN NABER 28]

anyone got a picture of flywheel inside magnets for k91

[buckrancher 2,679]

Ken if no one has posted a pic when I get home to night I'll take a picture of a nos flywheel and post it for you

Brian

[buckrancher 2,679]

[KEN NABER 28]

here is mine

mine looks different comments please

[buckrancher 2,679]

I hope TT chimes in I have not seen one like that

Brian

[KEN NABER 28]

any way of getting a replacement ? someone sell this item?

[buckrancher 2,679]

I may have a good used one I will look

Brian

[TT-(Moderator) 1,131]

I had a 1979 K-91 that I believe had that magnet style. (been a while ~ sorry I can't quite remember)

@Ken: can you post the spec and serial number from your engine, and/or does it have a silver ID sticker vs. a metal tag?

[KEN NABER 28]

Here are some pics, also note that hood support has no accomodation for the sector stop arc device, also the pulley guard does not expose pulley for implement drive, also the pulleys seem large. are these factory or homebuilt?

[KEN NABER 28]

pic with numbers

[TT-(Moderator) 1,131]

That wrecks that idea...... that tag is from a K-91 with gear reduction. (apparently from an Eska snowblower)

Do you have pictures of the magneto?

The hoodstand is a 'home-built' replacement. Not a bad job either, but definitely not OEM.

[KEN NABER 28]

here ya go! thanks for your help!!!

[buckrancher 2,679]

I do have a used one like the one in the picture i posted

Brian

[KEN NABER 28]

my email is included private message how much

Edited November 27, 2012 by KEN NABER