Firing on one cylinder

worntorn · Jul 22, 2022

I would change the condensers. It's only a few dollars and 20 minutes of work to do this. If the problem persists then condensers have been ruled out.
A coil can act up intermittently.
Two years before I was born, my father purchased a new 1952 Chevrolet. With a brand new car and the implied reliability, the family immediately set off on a 3000 mile round trip to California in search of winter sun. The new Chevy bucked and misfired all the way to L.A. and home again.
It visited many GM dealer shops along the way. None were able to find the cause of the problem, which would only show up after half an hour or so of driving.
Finally it was the little selling Dealership in White Rock, B.C. that figured it out. The problem was a faulty coil that intermittently acted up when warm.

Glen

Thomasa · Jul 22, 2022

In WEM's case, I'd bet on condensers. Bear in mind that infant mortality in automotive condensers is high. I've done hundreds of tune ups and unless there's some indication of a problem (like big mound of metal on one point) I leave them be. I have had ones I replaced fail very soon. I once had to pay the tow to keep the customer happy and keep my reputation. However...

I was hunting an elusive tuning problem and eventually checked the resistance of the wires from coil to plug terminal. One wire was 20K ohms and the other was 10K. Same length. Oh boy, I thought, I've found the problem. Date code was old. Replaced both wires. New ones measured 5K. Rode bike. Same problem. But now I have proper-resistance wires. I have found that resistance wires can create intermittent problems often but not always heat related. FWIW I've never seen an NGK resistance cap fail. My tuning problem turned out to be mis-matched mufflers.

MexicoMike · Jul 23, 2022

FWIW, even with good condensers you can still have slight sparking. So don't don't condemn a condenser just because you see a bit of spark. Of course, as noted, they are inexpensive so changing them is not financially painful!

Re coils - my favorite coil-failing experience was a coil (automobile) that cut out in hard left turns. It was fine in 'normal' left hand turns!

worntorn · Jul 23, 2022

It's just a cheap, simple thing to do to eliminate possibilities with a misfire, especially when one set of points is sparking much more than the other, as OP mentioned.
Much like we put new plugs in to eliminate that as the cause of the misfire.
Plugs first, condenser(s) second.

Glen

Torontonian · Jul 23, 2022

Again , change out the older condensers for new and file the points. Also grease the heck out of the AAU. plate behind the points plate regularly. Re- time too.

Mart UK · Jul 24, 2022

Random thought: I got through a pair of spark plugs in under 200 miles. Stuttering and started firing on just the right cylinder. Realised re-torquing the head had changed the tappet clearances. Re-set them and fine since. The left plug in particular was black.

WEM · Jul 24, 2022

Still trying to determine what is causing my bike to sputter under acceleration. I pulled the coil pack and tested the coils. The primary windings for both coils tested in spec. The Manual specifies a range of 1.7 to 1.9 ohms. My coils tested at 1.8 ohms. I also tested the secondary windings using a method I came across somewhere on the Internet. I can't recall exactly where I found the info but I remember the chap saying that the thing to look for when testing the secondary windings was that the readings for both coils were approximately the same. My coils tested at 5,760 and 5,820 ohms, a 1% difference, which I hope is close enough. Anyway, based on the foregoing, I think the coils are OK and am potentially ruling them out as the source of the problem which leaves the condensers. I came across a test for condensers which indicated that when the multimeter is set to ohms, placing one lead of the meter on the male wiring connection tab while touching the other lead to the body of the condenser should result in the reading on the meter climbing steadily. However, when I did the test my meter dropped to 0 for both condensers. I was expecting one condenser to be defective but not both so now I'm not sure if both condensers are bad or if I'm doing the test incorrectly. Bottom line is I think I'm going to buy two new condensers. I don't like buying parts based on the assumption that something might be wrong. I much prefer knowing the part being replaced is defective. My wife says I'm cheap but I prefer to think I'm frugal. However, condensers are relatively inexpensive, so unless someone can provide an alternate test method for condensers, looks like I'm buying two condensers.

kommando · Jul 24, 2022

When I ran an 1100 Golf the maintenance schedule had you changing the condensers every 20000 miles along with the distributor cap, they are seen as consumable items.

Craig · Jul 24, 2022

Buying a couple condensers is no different than buying a set of spark plugs , neither item lasts for ever and are usually the first things to look at in your situation … surprised no one has mentioned E.I. , so I won’t ….

worntorn · Jul 24, 2022

WEM said:
Still trying to determine what is causing my bike to sputter under acceleration. I pulled the coil pack and tested the coils. The primary windings for both coils tested in spec. The Manual specifies a range of 1.7 to 1.9 ohms. My coils tested at 1.8 ohms. I also tested the secondary windings using a method I came across somewhere on the Internet. I can't recall exactly where I found the info but I remember the chap saying that the thing to look for when testing the secondary windings was that the readings for both coils were approximately the same. My coils tested at 5,760 and 5,820 ohms, a 1% difference, which I hope is close enough. Anyway, based on the foregoing, I think the coils are OK and am potentially ruling them out as the source of the problem which leaves the condensers. I came across a test for condensers which indicated that when the multimeter is set to ohms, placing one lead of the meter on the male wiring connection tab while touching the other lead to the body of the condenser should result in the reading on the meter climbing steadily. However, when I did the test my meter dropped to 0 for both condensers. I was expecting one condenser to be defective but not both so now I'm not sure if both condensers are bad or if I'm doing the test incorrectly. Bottom line is I think I'm going to buy two new condensers. I don't like buying parts based on the assumption that something might be wrong. I much prefer knowing the part being replaced is defective. My wife says I'm cheap but I prefer to think I'm frugal. However, condensers are relatively inexpensive, so unless someone can provide an alternate test method for condensers, looks like I'm buying two condensers.

If the new condensers make no difference, then keep the old ones as spares, they weren't the problem in that case. So no $ is wasted.
You should always pack spare condensers, points, plugs and at least one coil on any long trip.
That is the beauty of the points ignition, you can carry a whole spare ignition as back up and it occupies very little space, costs peanuts and can be fitted roadside.

I had a condenser go when on a long trip. The bike went onto one cylinder. Found a quiet spot, determined which cylinder was dead, put in spare condenser and back riding in about 30 minutes.

Glen

Steves · Jul 25, 2022

I think you will find it’s the carburettor at fault.

WEM · Jul 25, 2022

The new condensers are on their way via Royal Mail. I’ll try them first. I had the Amal Premiers (3 years old) apart this past winter when I had to do some work on the float bowls. One carb tickled much faster than the other. Everything else in the carbs looked really good, almost brand new. I replaced the gaskets and such and reassembled diligently, I think. It might be possible that something has moved. If the condensers don’t solve the issue, the carbs will be my next step. The main reason I dread to go near the carbs are those rubber boots. Reinstalling them has got to be one of the most frustrating things on the bike.

Craig · Jul 25, 2022

Try a hair dryer to warm ?

Torontonian · Jul 25, 2022

WEM said:
Still trying to determine what is causing my bike to sputter under acceleration. I pulled the coil pack and tested the coils. The primary windings for both coils tested in spec. The Manual specifies a range of 1.7 to 1.9 ohms. My coils tested at 1.8 ohms. I also tested the secondary windings using a method I came across somewhere on the Internet. I can't recall exactly where I found the info but I remember the chap saying that the thing to look for when testing the secondary windings was that the readings for both coils were approximately the same. My coils tested at 5,760 and 5,820 ohms, a 1% difference, which I hope is close enough. Anyway, based on the foregoing, I think the coils are OK and am potentially ruling them out as the source of the problem which leaves the condensers. I came across a test for condensers which indicated that when the multimeter is set to ohms, placing one lead of the meter on the male wiring connection tab while touching the other lead to the body of the condenser should result in the reading on the meter climbing steadily. However, when I did the test my meter dropped to 0 for both condensers. I was expecting one condenser to be defective but not both so now I'm not sure if both condensers are bad or if I'm doing the test incorrectly. Bottom line is I think I'm going to buy two new condensers. I don't like buying parts based on the assumption that something might be wrong. I much prefer knowing the part being replaced is defective. My wife says I'm cheap but I prefer to think I'm frugal. However, condensers are relatively inexpensive, so unless someone can provide an alternate test method for condensers, looks like I'm buying two condensers.

I'm a firm believer in substitution , as in replace the questionable part with a known good substitute to help trace down the problem. And yes , always listen to the wife too. Happy wife , happy Life.

WEM · Aug 4, 2022

I haven’t updated in a while. I wanted to get some test rides in before updating. Pleased to report that new condensers and new plugs, for good measure, seem to have addressed the issue I was having. Bike is running well. Thanks to all for their help.

ewgoforth · Aug 4, 2022

Tornado said:
Swap the HT leads so left coil fire right plug etc and then determine if the misfire stays put or migrates to other side. That will tell you if a coil is the issue. Even new coils can fail. If the clamp bracket is too tight it can crush the outer coil wall and lead to shorting internally.

With points there isn't a "spare spark" you need to switch the position of the coils.

Tornado · Aug 4, 2022

ewgoforth said:
With points there isn't a "spare spark" you need to switch the position of the coils.

Understood but connecting left coil to right plug and vis versa will tell you if the one coil (of one side of the points) has a problem.

Firing on one cylinder

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