Author Topic: Still chasing ignition woes  (Read 2304 times)

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Offline Bankerdanny

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Still chasing ignition woes
« on: June 10, 2020, 03:52:01 PM »
I know there are multiple threads on this topic and I have read a lot of them, but I still can't seem to solve the 2-3 spark issue I have been having for over a year.

I had this issue briefly at the beginning of my week long trip last year, but I replaced the 2-3 condenser, which had been rubbing on something and had a bare spot in the insulation on the wire out, and that seemed to solve it until literally the last few miles of the trip, when it came back and hasn't gone away.

I have tried on and off to solve it to no avail.

- Yesterday I set the points and double checked the timing.
- When I swap the blue wire from the 1-4 points into the yellow wire into the 2-3 coil I get a nice fat spark, so the problem would seem to be the 2-3 circuit.
- I have measured the plug ends and coil resistance and all are within spec.
- I tried running a new yellow wire from the points to the coil and it made no difference.
- I installed new terminal ends on every wire in the 2-3 points circuit.
- I swapped out the condenser for another I had on hand.
- I reconnected my Hondaman ignition, which isn't dependent on the condensers, and it didn't help.

I am at a loss as to what to try next.
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Current: '76 CB750F. Previous:  '75 CB550F, 2007 Yamaha Vino 125 Scooter, '75 Harley FXE Superglide, '77 GL1000, '77 CB550k, '68 Suzuki K10 80, '68 Yamaha YR2, '69 BMW R69S, '71 Honda SL175, '02 Royal Enfield Bullet 500, '89 Yamaha FJ1200

Offline scottly

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Re: Still chasing ignition woes
« Reply #1 on: June 10, 2020, 04:51:32 PM »
Did you verify if the coil mounting brackets are positioned properly?
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Offline Bankerdanny

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Re: Still chasing ignition woes
« Reply #2 on: June 10, 2020, 05:18:43 PM »
Did you verify if the coil mounting brackets are positioned properly?

As far as I know it is. I'll take a look at my buddy's bike tomorrow to see if my setup matches.
"The problem with quotes on the Internet is that you never know if they're true" - Abraham Lincoln

Current: '76 CB750F. Previous:  '75 CB550F, 2007 Yamaha Vino 125 Scooter, '75 Harley FXE Superglide, '77 GL1000, '77 CB550k, '68 Suzuki K10 80, '68 Yamaha YR2, '69 BMW R69S, '71 Honda SL175, '02 Royal Enfield Bullet 500, '89 Yamaha FJ1200

Offline ekpent

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Re: Still chasing ignition woes
« Reply #3 on: June 10, 2020, 05:26:37 PM »
  Wish you were closer as Sean or I would plop a whole new coil set-up on it real quick to check. Don't have a spare unmolested stock set around ? Maybe rob your friends for a check. No power then at all to the 2/3 points ?  Hmm, it has to be something fairly easy I hope.
« Last Edit: June 10, 2020, 05:29:30 PM by ekpent »

Offline scottly

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Re: Still chasing ignition woes
« Reply #4 on: June 10, 2020, 05:28:50 PM »
If the 2-3 coil worked with the 1-4 points, the coil isn't the problem. Is there no spark at all?
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Offline ekpent

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Re: Still chasing ignition woes
« Reply #5 on: June 10, 2020, 05:31:30 PM »
Handy time for a meter or test light down there on the points.

Offline seanbarney41

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Re: Still chasing ignition woes
« Reply #6 on: June 10, 2020, 05:33:23 PM »
iirc, the bracket can be mounted to the frame upside down with the coils still right side up, which causes the bracket to interfere with the primary wires on 2-3...that was a problem I had that was very hard to catch.  Especially, since primary wires are insulated you don't suspect the problem.
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Offline scottly

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Re: Still chasing ignition woes
« Reply #7 on: June 10, 2020, 05:37:27 PM »
Danny, remember Matt's bike at Dolores? The wires at the points were hooked up in the wrong order with the insulators on the screws, grounding the coil wire.
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Offline scottly

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Re: Still chasing ignition woes
« Reply #8 on: June 10, 2020, 05:43:56 PM »
Sean, the brackets have an off-set of the post where they mount to the frame. The front mount is offset to the left, and bolts onto the left side of the frame, while the rear is turned so the off-set is to the right. Note the relief on the front bracket faces to the rear.
« Last Edit: June 10, 2020, 05:48:59 PM by scottly »
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Offline Bankerdanny

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Re: Still chasing ignition woes
« Reply #9 on: June 10, 2020, 06:06:53 PM »
Fortunately I have buddy's F3 with the original ignition setup to look at for reference
"The problem with quotes on the Internet is that you never know if they're true" - Abraham Lincoln

Current: '76 CB750F. Previous:  '75 CB550F, 2007 Yamaha Vino 125 Scooter, '75 Harley FXE Superglide, '77 GL1000, '77 CB550k, '68 Suzuki K10 80, '68 Yamaha YR2, '69 BMW R69S, '71 Honda SL175, '02 Royal Enfield Bullet 500, '89 Yamaha FJ1200

Offline scottly

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Re: Still chasing ignition woes
« Reply #10 on: June 10, 2020, 06:13:36 PM »
The coil bracket is probably not the issue, since the 1-4 points fire the 2-3 coil...
Poke your meter + probe into the 2/3 connection at the coil end, with the negative probe grounded. You should read 12V when the points are open, and zero when they are closed. 
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Offline seanbarney41

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Re: Still chasing ignition woes
« Reply #11 on: June 10, 2020, 07:00:18 PM »
Sean, the brackets have an off-set of the post where they mount to the frame. The front mount is offset to the left, and bolts onto the left side of the frame, while the rear is turned so the off-set is to the right. Note the relief on the front bracket faces to the rear.
yeah, no idea what I did wrong, as now that I look at your pictures there are dozens of wrong ways to assemble that I am seeing, if you take all that stuff completely apart
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Offline Deltarider

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Re: Still chasing ignition woes
« Reply #12 on: June 11, 2020, 01:22:52 PM »
What bike? This is what I'd check at the breakerpoints 2+3:
After first checking the yellow wire's fork connector does not accidentely ground, disconnect for the moment the yellow wire from the 2+3 breakerspoints.
IGN is switched off. Now connect one probe of an ohmmeter to ground and the other to the tiny bolt at the back of the breakerpoints 2+3. When points are closed, meter should read 0, provided the point surfaces are clean.
When points open, meter should read 1, meaning infinite. If there's still some continuity, breakerpoints have to be inspected for a possible problem with the insulators. One of them is a minuscule one in the middle, in the center. It is there to insulate the little bolt. It's a real tiny one and sometimes it is not in the right position. Not often, but it can happen!
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Offline Bankerdanny

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Re: Still chasing ignition woes
« Reply #13 on: June 11, 2020, 03:07:49 PM »
Deltarider, '76 750F.

Here's where things stand. I double checked how everything was attached at the coils against my buddy's unmolested 750F3 and all the wiring is the same.

When the 2-3 points are open I have power all the way to the coil. There is some voltage drop (12.7 at the battery but 11.7 at at the coil), but the blue 1-4 wire shows the same voltage drop and it works fine.

Just for the hell of it I swapped out the front bracket as I had made some relief cuts in the original when I was trying to fit up Accel coils last year. No change.

I did note that when I turn the key off and let it sit for a little while then turn it back on and hit the start button my test plug has a weak spark at the 2-3 leads, but it only lasts a second or so, then there is no more spark. Could it still be a bad condenser? I will try swapping the 1-4 condenser over to the 2-3 circuit and see if that makes a difference.
"The problem with quotes on the Internet is that you never know if they're true" - Abraham Lincoln

Current: '76 CB750F. Previous:  '75 CB550F, 2007 Yamaha Vino 125 Scooter, '75 Harley FXE Superglide, '77 GL1000, '77 CB550k, '68 Suzuki K10 80, '68 Yamaha YR2, '69 BMW R69S, '71 Honda SL175, '02 Royal Enfield Bullet 500, '89 Yamaha FJ1200

Offline Bankerdanny

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Re: Still chasing ignition woes
« Reply #14 on: June 11, 2020, 04:33:28 PM »
As best as I can tell everything is connected correctly. The points and condenser wires are attached to the points in the same way as on my buddy's bike, which has spark at all 4 plugs. I swapped the 2-3 condenser from the other bike to mine and still no spark. I am really at a loss here.
"The problem with quotes on the Internet is that you never know if they're true" - Abraham Lincoln

Current: '76 CB750F. Previous:  '75 CB550F, 2007 Yamaha Vino 125 Scooter, '75 Harley FXE Superglide, '77 GL1000, '77 CB550k, '68 Suzuki K10 80, '68 Yamaha YR2, '69 BMW R69S, '71 Honda SL175, '02 Royal Enfield Bullet 500, '89 Yamaha FJ1200

Offline Kevin D

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Re: Still chasing ignition woes
« Reply #15 on: June 11, 2020, 05:14:08 PM »
Danny, how old are your spark plug caps? What did they measure? Go out in the dark with your bike and a mister bottle and spray them plug caps a bit. See if there is any blue sparking going on.
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Offline Bankerdanny

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Re: Still chasing ignition woes
« Reply #16 on: June 11, 2020, 05:17:25 PM »
Kevin, the plug caps are about 18 months old and have at best 2k miles on them. I tested them yesterday and they all measured within 10% of 5k ohms, so they are in good shape.
"The problem with quotes on the Internet is that you never know if they're true" - Abraham Lincoln

Current: '76 CB750F. Previous:  '75 CB550F, 2007 Yamaha Vino 125 Scooter, '75 Harley FXE Superglide, '77 GL1000, '77 CB550k, '68 Suzuki K10 80, '68 Yamaha YR2, '69 BMW R69S, '71 Honda SL175, '02 Royal Enfield Bullet 500, '89 Yamaha FJ1200

Offline Kevin D

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Re: Still chasing ignition woes
« Reply #17 on: June 11, 2020, 05:27:51 PM »
Kevin, the plug caps are about 18 months old and have at best 2k miles on them. I tested them yesterday and they all measured within 10% of 5k ohms, so they are in good shape.

All sounds good Dan, but still, something is not good. an ohmmeter wont pick up a cracked cap but a spray bottle will.
Are the spark plug insulators clean as a whistle?
You dont have the dreaded Daiichi condensers do you? with the flower?
71 CB750 K1
104,000 miles
Original Owner
———past———
70 SL100/125/150
70 Candy BlueGreen CB 750 K0
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Former Honda parts kid/counter kid/do all
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Whether you think you can or think you can’t, you’re right
Genius is 99% perspiration, 1% inspiration

Offline scottly

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Re: Still chasing ignition woes
« Reply #18 on: June 11, 2020, 05:48:23 PM »
He had a good spark with the 1-4 points connected to the 2-3 coil, so the problem has to be on the points side of the system.
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Offline Robbo

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Still chasing ignition woes
« Reply #19 on: June 11, 2020, 05:49:15 PM »
As best as I can tell everything is connected correctly. The points and condenser wires are attached to the points in the same way as on my buddy's bike, which has spark at all 4 plugs. I swapped the 2-3 condenser from the other bike to mine and still no spark. I am really at a loss here.
Swap out your 2-3 coil and spark plug wires with your buddy.

Try his set on yours.  If his works on your bike great.  Now just as a confirmation, try your set on his bike.  If it fails to work on his too, replace your entire 2-3 set and ride on .


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« Last Edit: June 11, 2020, 05:51:51 PM by Robbo »
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Offline scottly

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Re: Still chasing ignition woes
« Reply #20 on: June 11, 2020, 06:46:12 PM »

- When I swap the blue wire from the 1-4 points into the yellow wire into the 2-3 coil I get a nice fat spark, so the problem would seem to be the 2-3 circuit.

It is NOT a coil problem!
Don't fix it if it ain't broke!
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Offline scottly

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Re: Still chasing ignition woes
« Reply #21 on: June 11, 2020, 06:48:44 PM »
The coil bracket is probably not the issue, since the 1-4 points fire the 2-3 coil...
Poke your meter + probe into the 2/3  primary connection at the coil end, with the negative probe grounded. You should read 12V when the points are open, and zero when they are closed.
Don't fix it if it ain't broke!
Helmets save brains. Always wear one and ride like everyone is trying to kill you....

Offline RickThomas

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Re: Still chasing ignition woes
« Reply #22 on: June 11, 2020, 07:12:51 PM »
Given that you've done the troubleshooting and narrowed it down to the points side (assuming temperature is not an issue such as a coil failing when warm) and that the ignition system is set to spec, there are a couple things I would look for:
1: Verify quality components as pointed out by others. (TEC is my go to for the points, condensers, and plate.)
2: Verify that the wiring and fiber plates are connected properly on the plates.
3: Verify properly functioning points by swapping with a known good set.

Offline Kevin D

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Re: Still chasing ignition woes
« Reply #23 on: June 11, 2020, 07:16:05 PM »
He had a good spark with the 1-4 points connected to the 2-3 coil, so the problem has to be on the points side of the system.

Sorry, I have not kept track of the swaps.
I just dont like it at all when the CB does not run right.


71 CB750 K1
104,000 miles
Original Owner
———past———
70 SL100/125/150
70 Candy BlueGreen CB 750 K0
————————————————-
Former Honda parts kid/counter kid/do all
—————————————————————-
Whether you think you can or think you can’t, you’re right
Genius is 99% perspiration, 1% inspiration

Offline scottly

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Re: Still chasing ignition woes
« Reply #24 on: June 11, 2020, 07:16:30 PM »
The simple voltage test will prove out the points themselves. I betting on #2. ;)
Don't fix it if it ain't broke!
Helmets save brains. Always wear one and ride like everyone is trying to kill you....