Ace 100B+ No Spark

[tyjolson]

Alittle background, I recently was gifted a Ace 100B+ that was found in a barn. The engine was filled with water but has been completely rebuilt. Now I'm trying to get it to fire up but have no spark. I am getting 4 Volts at the spark plug connector (Very low) which points me towards the ignition coil. Anyone have any advice? What should the nominal voltage output be?

[thrownchain]

New points and condenser? Flywheel rust free? Wires and connections clean and corrosion free? New plug? Good ground connection?

[Hydraulic Jack]

By "spark plug connector" might I assume you mean the cap that connects to the spark plug? If so, I don't think I have ever seen a value for coil output for the Hodaka. Most such coils will produce voltage in the tens of thousands of volts. Not something I would have thought to test with a multi-meter.

Start with a thorough cleaning of all parts of the magneto. Pull the flywheel. Remove and clean the coils carefully. Be sure the inside of the flywheel is bright and shiny, not rusted. Replace the points and condenser if for no other reason than they have been under water. Verify the resistance of each of the primary coils as published in the specs or the repair manual. Verify all of the wiring connections to be clean and close to zero resistance.

No magic bullet here. This calls for diligent cleaning from the engine case outward. The secondary coil, under the tank, would be my last suspect. It is more likely for the spark plug cap connection to be faulty than for the coil to fail.

[givergas]

when you say, remove and clean coils what exactly do you mean ? just the connections, and where the screws seats, or do you have something else in mind. im cleaning my magneto today as it was sitting in water also new points and condenser on the way. good timing asking this question right when i needed it. learn more by accident here than if you tried ......

[tyjolson]

Thanks everyone! I'll take it back apart and double check the magneto here in the upcoming weeks.

[Hydraulic Jack]

I was suggesting dismounting the coils and visually inspecting areas that would otherwise not be visible. Two reasons. One, there is no spark, so it could be anything from simple to not so much. Might as well take a look. Two,it was immersed in water, and there could be corrosion or other fault in the coil windings. There isn't so much you can do for a primary coil, but scratches can be recoated with lacquer, sand and dirt can be removed, and if broken windings can be seen, you will have an idea of why it doesn't work. I would start with the resistance test, but to do that right, you have to disconnect everything, at which point you are two screws away from dismounting the coil, and with the condenser off, you can test that for capacitance.

Probably the most frequent reason there is no spark is a fouled plug, then faulty points. But with water intrusion, I would look for corrosion on the inner part of the flywheel and the ends of the coil core. A layer of rust can stop the magneto from working even when everything else is okay. With a bike that has either been out in the rain for the past couple decades, or one that was in a barn but was also under water (??), I would not have an idea what could be the problem without thoroughly looking it over. That's why I suggest taking it completely apart.

[Bullfrog]

One slight "edit" to Hydraulic's most recent post on this thread: In order to do both recommended tests to the primary coil, you'll need to remove the coil from the stator plate. The two recommended tests are 1) coil winding resistance test and 2) "short-to-core" test. It is that second test which requires isolating the complete coil from the stator.
Ed

[Hydraulic Jack]

Technically, when doing just the short to ground test, you will get the same electrical answer whether the coil is mounted or dismounted -- assuming you also get continuity between engine case and stator plate, and between stator plate and coil core. Each of these pieces is screwed together creating a continuous path to ground.

But for diagnostic reasons, take the coil off the stator plate. This eliminates variables, and when you don't have any idea why something isn't working, it is necessary to eliminate all other variables and test only one variable at a time. You should also test continuity between engine case, stator plate, and coil core when reassembling the magneto to verify that when done, you do in fact have continuity from coil core and stator plate to ground.

The one test that absolutely requires electrical isolation is the condenser. Since the condenser is soldered into the circuit, regular testing isn't practical. Here, however, take everything apart and test each part separately. Remember to record answers to resistance and capacitance for cross reference to the manual. That way you don't have to remember tomorrow what the answers were today.

[Bullfrog]

While coil continuity to ground can be tested with the coil on the stator, testing for the fault, "short to coil core" requires removing the coil from the stator.
Ed

[Hydraulic Jack]

Actually, Ed, no it doesn't. While the coil lead should be disconnected from the wiring harness so that it is isolated that way (and the lead should be disconnected anyway for any testing), the windings don't touch anything else but the iron core. Whether you have a short registered at the core, or at the stator plate if the coil is mounted, or at the engine case with the coil mounted, the answer is the same. Continuity at the stator can only come through the core, so it isn't required to dismount the coil to test for short. I don't doubt you have thought so for a long time, and we all tend to rely on our memories and experience, but there is no electrical reason to dismount the primary coil to test for short to ground. If you can describe an alternative pathway to ground that requires a dismount, feel free.

[Bullfrog]

Ah, but the output end of the exciter coil is soldered to the condenser, which is connected to the points . . . and both of those items are connected to ground (stator plate and through the stator plate to the coil core). It appears you are assuming both of those items have been removed from the stator plate . . . and I haven't made that assumption. Removing the coil from the stator plate is the simplest, easiest way to complete a definitive "short to coil" test. (and if the coil is still connected to the condenser and points and if they are still mounted to the stator, then coil removal is required)

Ed

[Hydraulic Jack]

Read what I wrote Ed. Electrically isolated, coil lead disconnected, isolated from the harness. It was mentioned several times. I made no assumptions here other than the OP's bike won't fire.

You can't test magneto components when all the wires are connected, so removing leads from the condenser is mandatory. If you have another method, enlighten.

[Bullfrog]

I just did. (Enlighten that is.) Probably enough sparring on this topic, don't you think.
Ed

[Hydraulic Jack]

We aren't sparring. You simply don't wish to admit you are wrong on the question that you, yourself, posed:

is it required that the primary coil be removed from the stator to be tested for short to ground?

The answer to this questions is NO. It is not required that the coil be physically removed from the stator in order to perform the mentioned test.

I have explained why it is not required that the coil be removed. You have not explained why it would be required, nor can you. It is that simple. I am not asking for a concession. It was your statement, not mine.

You can't enlighten folks with misstatements.

[matt glascock]

Just my 0.02. Mind you, I'm not an experienced motorcycle mechanic. I'm a passionate (rank) amateur motorcycle mechanic. However, my training and profession requires a very methodical, systematic, deductive approach to problem solving. Happily, this training applies to any situation where complex problem solving is the call. Complexity defines the conundrum you now confront. When the question of the dreaded lost spark arises, and a simple inspection/cleaning of the points doesn't save the day, I take the entire rotor/stator assembly apart to the individual components, clean, inspect, and test each component individually, and replace as required. Pay attention to the rotor as well. For the rotor, completely derust (I've used Evaporust effectively), use compressed air to blow out all moisture from all the nooks and crannies, make sure there is not any iron filings etc. stuck to the magnets, give it a good blasting of WD-40, then wipe dry. With something as potentially frustrating and tedious as chasing down the cause of a "lost spark", a methodical approach is key. Be systematic and comprehensive. Isolate and evaluate each component of the ignition system individually. From the main switch to all the wires, connectors, solder joints, magneto components, coil, plug wire and plug connector, the whole system should be examined. While this method seems time consuming, in the long run, you will save time and, most importantly, frustration. Speaking of isolating, you have taken the main switch out of the equation by now? It would be hell going through all this to find that the main switch is toasted. If you have not bypassed the main switch, remove the seat, find the nylon wire coupler which attaches the wires coming directly off the main switch to the rest of the wiring loom and unplug it. Then test for spark. Isolate/test/isolate/test...you'll find the problem best this way.

[Bullfrog]

I bow to the master, Hydraulic Jack.

While it is not technically required to remove the coil from the stator conduct a definitive test of "short to ground" on the coil windings (so you "win" Hydraulic), years of experience with "long distance diagnosis" has taught me a thing or two. If I'm doing long distance diagnosis and a home based Hodie mechanic tells me he has detected a short-to-ground failure of the exciter coil windings, I'm going to ask him how he did the test. And if he didn't remove the coil from the stator, I'm going to ask him to re-do the test with the coil removed from the stator in order to remove as many variables as possible.

Please accept my apology for the severe technical error. You were right and I was wrong.
Ed

[givergas]

excellent post if it wasn't for your passion and knowledge theres no way we {shade tree mechanics} would get down and dirty with a magneto..... be brave gentleman.....