Another No Spark Post...

[Ambo_bubba]

Hello again, I am here to beat what I am sure is a dead horse, but looking for some advice. Today, after being two years into my winter project that turned into a nuts and bolts restoration... I finally buttoned up my 71 Moto Guzzi Ambassador and turned it over and low and behold, no spark... 

So, during this restoration, I rebuilt the distributor, replacing the points and condensers, installed a Greg Bender wiring harness, and converted to an alternator. The only ignition thing I didn't do was replace the ignition coil.

I do have a new coil on order, but would love to avoid having to pull the tank, especially now that it is full of gas. What are some easy checks I can do now while I wait on the new coil to try to pin point the issue? Are there common places that I could have gone wrong? There is no spark at the plugs and at the coil, and am armed with a volt meter ready to go 

For what it's worth, the bike did not run when I got it (electrical shenanigans from a PO before it sat for 20+ years)

Thank you in advance!!!!

[Ambo_bubba]

At this point it is owed... here's a pic of it all buttoned up

[n3303j]

Do you have DC voltage at the coil that switches as the points open and close? Low resistance between coil low voltage terminals? Higher resistance between coil output and ground?
That will get you and your meter started on a solution.

[John A]

Condenser is a likely cause as well.

[Antietam Classic Cycle]

Even new points can have dirty contacts, try cleaning them. New condensers can be bad out of the box, this is quite common. Try the old one.

The tachometer sometimes has an internal fault and grounds out the ignition. Try disconnecting the black wire to the tach. 

[Ambo_bubba]

Do you have DC voltage at the coil that switches as the points open and close?

Am i measuring this at both terminals on the coil? or just one? It is a bosch coil

I'll try switching the condenser back to the old one, for the points, I did clean them. Will tinker tonight and update. Thanks all!

[n3303j]

Am i measuring this at both terminals on the coil? or just one? It is a bosch coil
[SNIP]

Both terminals. One line should be constant hot (Ignition ON) when measured to frame ground. The other line is ground that is switched on and off by the points closing.

[Ambo_bubba]

Ok, results of a bit of tinkering. The coil always has 12v to both the positive and negative terminals. Even with the distributor wire removed it is constantly putting out 12v. Does this seem correct? Is the coil supposed to send 12v to the condenser who then interrupts the ground?

If that's the case, the points opening and closing have no effect on grounding the negative terminal on the coil.

And right now the tach is disconnected.

Thanks!

[Ambo_bubba]

Update, disconnect the new condenser, and now the points are no longer constantly grounded. Replacing with the old one now.

Is conventual wisdom not to replace the condensers when doing tune ups on these bikes? If not, which one should be purchased?

Thanks!

[Ambo_bubba]

More electrical shenanigans...

Switched out the condenser for the old one and the points where now no longer grounded when open. Big win! Except as soon as I re attached the wire to the coil, the system was once again grounded full time and at a constant +12v with the ignition on.

With everything disconnected from the negative terminal on the coil, I have continuity between the negative terminal and the ground.

Back to bad coil? 

[n3303j]

Update, disconnect the new condenser, and now the points are no longer constantly grounded. Replacing with the old one now.

Is conventual wisdom not to replace the condensers when doing tune ups on these bikes? If not, which one should be purchased?

Thanks!

Sounds like you found the problem. New points / new condenser was standard tune up 60 years ago when Echlin Blue Streak made products in the USA and they were reliable. Not so anymore. My T3 still has the original Magnetti Marelli capacitors after 125,000 miles. I don't dare change them.

[n3303j]

Take capacitor out of circuit.
Disconnect wire from points at the coil.
Measure resistance between wire from points to frame ground. You should get infinity or zero resistance as you rotate engine to open or close points. If you can't get infinity then your points are shorted. I've seen misplaced insulating washers short out points.

[Tom H]

In addition/clarify to what N3303J wrote. Look where the spring for the points is bolted/attached to the dist. body. It should be bolt, spring, insulator, outer insulator, nut and then the coil and cond. and then another nut.

Maybe that will do it?
Tom

[Ambo_bubba]

So the new capacitor was definitely problematic, when connected to the distributor post it would ground both side of the points rendering them useless! After swapping back in the old one, everything checked out ok but after reconnecting the coil, I am back to a grounded system 100% of the time. When I removed the coil from the bracket, so that it wasn't physically touching the bike, the problem went away... I didn't test for spark but I was now seeing a switched voltage on the negative terminal as the points rotated.

So somehow the negative post oil is grounding itself to the frame via the coil body. I couldn't find anywhere with continuity between the body and the negative terminal.

I have half the mind to wrap it with electrical tape before remounting it, but I might as well wait for the new one to come in at the end of the week to see if that resolved my issue.

Ill be back with an update once I get the new one. 

[Ambo_bubba]

New coil is in... Still no spark. Further diagnosing led me to find that when cranking the coil loses power. The +12v wire goes dead.

The battery is getting low on power now that I've been cranking it for a few days attempting a start. I'm hoping to try again after giving it a charge in the morning, but if no luck, is there an issue with the ignition switch?

I do not have a starter button but just the switch, that engages the starter like a car.

Thanks!

[Tom H]

Your switch could be the problem since you have found that you loose power TO the coil while cranking. I have a truck that the key switch went bad. You could crank all day and no start, other times it fired up fine. But sometimes as you let off the key it would fire. Bad contact in the switch.

Try jumping your starter with a heavy wire or the like with the key in just the ON position.

Tom

[Antietam Classic Cycle]

Could be the fuse that powers the coil. Every Loop that comes through the shop gets the fuse holders cleaned (with the wire brush in a Dremel) thoroughly and bent together so that they grip the fuses more tightly. Clean the ends of the fuses as well. Same with where the wires plug into the fuseblock and terminal board.

If you need to clean the contacts inside the ignition switch, here's how:
https://www.thisoldtractor.com/moto_guzzi_loopframe_ignition_switch_rebuild.html

[Ambo_bubba]

The fuse box is new with one of the josh Cole fuse boxes. I jumped the starter and sure enough the coil got power while cranking. I pulled the ignition switch out and cleaned it up, coil power problem solved...

On to the next, the points are not closing, I have them gapped at .014" and even when closed their is no continuity across them. I did pull them apart and clean them lightly with 1000 grit sand paper. For my own sanity, I did jump the points with a screw driver and got spark, so I'm decently certain I am down to the final issue.

Am I missing something on setting the gap for the points? How clean is clean enough on brand new points?

On an unrelated note, this has given me a good chance to look at my wiring thoroughly. Should the headlight come on without the bike running? Right now it does not but if you use the blinkers (with the lights off) the headlight comes on, after that if you turn on the lights and turn off the blinkers the low beam stays on. The highbeam doesn't turn on. Am I correct to assume that this is just a weird quirk and when running the headlight works as expected?

Thanks all!

[Antietam Classic Cycle]

The fuse box is new with one of the josh Cole fuse boxes. I jumped the starter and sure enough the coil got power while cranking. I pulled the ignition switch out and cleaned it up, coil power problem solved...

On to the next, the points are not closing, I have them gapped at .014" and even when closed their is no continuity across them. I did pull them apart and clean them lightly with 1000 grit sand paper. For my own sanity, I did jump the points with a screw driver and got spark, so I'm decently certain I am down to the final issue.

Am I missing something on setting the gap for the points? How clean is clean enough on brand new points?

On an unrelated note, this has given me a good chance to look at my wiring thoroughly. Should the headlight come on without the bike running? Right now it does not but if you use the blinkers (with the lights off) the headlight comes on, after that if you turn on the lights and turn off the blinkers the low beam stays on. The highbeam doesn't turn on. Am I correct to assume that this is just a weird quirk and when running the headlight works as expected?

Thanks all!

.014" is a little tight IMO, I use .016". The contact points can get "dirty" from just being in storage, clean enough is when you get continuity through them.

Yes, the headlight should come on with the engine not running, but key on. It shouldn't come on with the blinkers. Not just a "weird quirk" and the headlight is likely not working properly even with the engine running. Something is amiss.

[Ambo_bubba]

Thanks for the confirmation on the headlight, I'll pull it out and see if I wired something funky.

For the points, here is something funky, I went ahead and disassembled everything again, and this time, this time using a brass feeler gauge instead of steel per my neighbors recommendation and they are definitely tighter. I'll gap to .016 once I get through these shenanigans and can see a spark.

But odd thing is, I've been testing continuity across the points, and with the key off, I have continuity across them, but when I turn on the key and the positive terminal gets 12v, the continuity goes away and the the points never manage to ground the system.

Thoughts? Keep cleaning?

[Tom H]

I'm going to start with a dumb question. Are you checking the point gap when the narrow lobe is opening the points? Wide lobe. or no lobe at all???

The points need to ground and unground to make the system work.

With the key off........Put your meter on the continuity Buzzer setting if it has one. With the points closed, touch one lead to the fixed point and one to the moving point it should buzz. Now spread the points open with the leads and the buzz should stop. This will prove that the points are making contact with each other.

Next with the key off..... With the points held open using the lobe on the dist. or a suitable substitute, touch one lead to the fixed point and the other lead to the dist. body. If it buzzes your good there. Next take one lead again to the fixed point with the point open  and one lead to the engine or battery NEGATIVE, it should buzz again. If so your good there. If not, then you have a ground issue from the dist. to the engine block/battery neg..
Now also check with the points open from the moving point to ground, there should be no buzz. If a buzz then the moving point is grounded for some reason.

Your points should now be working.

I am used to doing this step with a test light. Attach the test light clamp to a good ground. Then turn on the key/ignition. Touch the test light to the bolt that holds the coil and cond. wire and rotate the engine by hand. When the points open, the light will go on, when closed the light will be off. If so, then you should be getting spark.

If so good so far, with the points closed, the dist. cap off and the ignition on. Take the coil wire out of the dist. cap. Hold near the head, now with a screwdriver open the points by pushing open the moving point, do not touch the screwdriver to a ground. When you open the point, the wire should have a spark to the head. You could also just rotate the engine by hand to open the points.

Hope this helps a bit.
Tom

[Ambo_bubba]

Tom, thanks for that systematic approach! I'll give that a good step by step and report back.

So far my attempt at diagnosing the points has been checking for continuity with a voltmeter, and listening for a buzz between the post on the distributor where the condenser and coil wire attach, and a ground, while turning the engine by hand. When I do that with the key off I get continuity on and off as the points open and close, but with the key on I do not.

Checking continuity across the points from the spring one and the static one yields the same results. Checking voltage with the key on between the post and a ground gives me full time 12v. Hoping when I step it out as you describe it'll present a problem. 

Been very frustrating to pin point and resolve a problem only to find another one

One step closer every time though! 

Will report back after I get a chance to work my way through that. Thanks!

[Tom H]

I have had issues testing the 12V power as you have done with a meter and have had the same issue. I firmly believe that a meter will show the voltage correctly, but for whatever reason it doesn't umm "always". Go to Harbor Freight or the like and buy a cheap test light. OR you can make one with some alligator clips, two lengths of wire and solder the wires to a 1156 type bulb.

Continuity with the key /ignition ON I do not believe will work. Only test with volts. I believe I have tried that way in the past.

One last thing I wanted to add....... In my 40 years with my Loops, I have had an issue at rare times when all I did was adjust the points. Nothing else except pull the plugs and clean them. Put the dist. cap back on and would not spark when I cranked the engine over. WTH?????? So, somewhere in the fog of time as to why, I took a screwdriver and wiggled the pegeebers out of the moving point for a few seconds causing sparks everywhere. I had sparks between the moving point and the fixed point, the dist. body and the drive for the dist.. For some reason that told me I had power there. Then I cranked the engine over with the coil to cap lead near the head and had spark. Again, I do not know how this fixed it, but it did, I have done this a number of times and it has worked. Just recently, it happened on a friends bike, tried it and it came to life.

Tom

[Ambo_bubba]

Sounds like it just needs a good reminder of what it means to spark!!!! I'll give that a shot if the test light tests don't show results. Now
to find some time. Thanks!

[Ambo_bubba]

I'm going to start with a dumb question. Are you checking the point gap when the narrow lobe is opening the points? Wide lobe. or no lobe at all???

The points need to ground and unground to make the system work.

With the key off........Put your meter on the continuity Buzzer setting if it has one. With the points closed, touch one lead to the fixed point and one to the moving point it should buzz. Now spread the points open with the leads and the buzz should stop. This will prove that the points are making contact with each other.

This was SAT except if the coil is connected to the distributor, the points have continuity across them even when open, with the coil disconnected there is no problem

Next with the key off..... With the points held open using the lobe on the dist. or a suitable substitute, touch one lead to the fixed point and the other lead to the dist. body. If it buzzes your good there. Next take one lead again to the fixed point with the point open  and one lead to the engine or battery NEGATIVE, it should buzz again. If so your good there. If not, then you have a ground issue from the dist. to the engine block/battery neg..
This was SAT

Now also check with the points open from the moving point to ground, there should be no buzz. If a buzz then the moving point is grounded for some reason.

SEE ABOVE, the negative coil is grounded
Your points should now be working.

Didn't get this far, I guess next step is to figure out why the negative post on the coil is grounded

I am used to doing this step with a test light. Attach the test light clamp to a good ground. Then turn on the key/ignition. Touch the test light to the bolt that holds the coil and cond. wire and rotate the engine by hand. When the points open, the light will go on, when closed the light will be off. If so, then you should be getting spark.

If so good so far, with the points closed, the dist. cap off and the ignition on. Take the coil wire out of the dist. cap. Hold near the head, now with a screwdriver open the points by pushing open the moving point, do not touch the screwdriver to a ground. When you open the point, the wire should have a spark to the head. You could also just rotate the engine by hand to open the points.

Hope this helps a bit.
Tom

I feel like everytime I test this I find something different...

[Ambo_bubba]

So with the key off, if the +12v wire from the ignition is plugged in, the negative on the coil is grounded. The coil has continuity across the posts and a resistance of 3.2 ohms.

On the coil positive, I have a black wire from the alternator, and a blue wire (+12v with ignition on), on the negative there's the wire from the distributor.

The bike doesn't have a damn kill switch on it or something? I'm going to pull the headlight to trace the blue wire

[Ambo_bubba]

So I plugged the negative wire into the coil, and then manually grounded it instead of letting the points do their thing, lots of sparks but I did verify that the negative post on the coil was switching between 12v and zero when doing this.

I'm still confused as to why everything is grounded when the wire is hooked up to the distributor...

Moving on to the next test now

[Ambo_bubba]

I did replace the condenser again for good measure, as well as the coil, and no change.

So with the original Bosch coil and a new pertronix flame thrower I have the same problem, as well as with the old condensers and new magneti Marelli condensers

[Tom H]

Try disconnecting the wire from coil + to the alternator, see if that solves your coil ground issue???

Tom

[Tom H]

So with the key off, if the +12v wire from the ignition is plugged in, the negative on the coil is grounded. The coil has continuity across the posts and a resistance of 3.2 ohms.

So this has me thinking...... With the 12v ignition wire connected to the + on the coil (got it so far) Then the - on the coil has no wire attached???, the coil is grounded? Or is the - wired to the dist.?

Tom