Author Topic: CB 650 '81 build 99% done with an electrical/timing problem  (Read 673 times)

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Offline Eric10024

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CB 650 '81 build 99% done with an electrical/timing problem
« on: January 17, 2023, 11:36:22 PM »
Hi everyone,

Im new to the forum (and forums overall). My plan was to make my first post about the project from start to finnish, however i have now encountered an issue that i am having a hard time solving. After i solve this problem, keep an eye on the project board as i will be making a rather long and comprehensive post about my project there.

The issue: Sparks on plugs 2&3 are working fine and using a timing-light i was able to confirm that everything is fine here. Sparks on plugs 1&4 are happening at the wrong time, when looking at the timing-wheel plugs 1&4 are sparking when the wheel has turned about 45 degrees past the point where it should have sparked. I tried placing the timing wheel in the position where plugs 1&4 should spark and using a screwdriver between the two points (the nock on the axel and the brush on the timing wheel) got plugs 1&4 to spark at the correct time.

Things i have tried:
-Changing the wires between coils and condensers. Result: no change, cylinders 1&4 did not fire.
-i can confirm that the cylinders are getting fuel, compression and the exhaust pathways are clear.
-Further i can add that i have not made any changes to the valves or engine overall since the summer when i rode the bike before the project.

Some background to what changes have been made to the bike:
-CV-carbs replaced with Keihin Cr Specials
-Exhaust changed to a 4-1 exhaust.
-Electricals rebuilt to an M-unit based system, everything else electrical is working on the bike flawlessly.
-Changed the plugs to new ones.

The mystery for me is the fact that plugs 2&3 are working flawlessly, and since this is the case, there is to my knowledge no mechanical way to adjust the timing to fix this problem.

Thank you for any advice, and please feel free to ask any questions i have neglected to include in my post.

« Last Edit: January 17, 2023, 11:49:22 PM by Eric10024 »

Offline Tracksnblades1

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Re: CB 650 '81 build 99% done with an electrical/timing problem
« Reply #1 on: January 17, 2023, 11:43:25 PM »
Are you still running the Honda wasted spark ignition?

Is 1& 3 firing correctly ?  Or 2&3 ?

You indicate both in different paragraphs of your post..
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Offline Eric10024

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Re: CB 650 '81 build 99% done with an electrical/timing problem
« Reply #2 on: January 17, 2023, 11:51:01 PM »
Hi,

I fixed the typo where regarding plugs "1&3" to "2&3", sorry about that.

Yes i am running the wasted spark system, with the all of the original parts.

Br,
Eric

Offline Tracksnblades1

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Re: CB 650 '81 build 99% done with an electrical/timing problem
« Reply #3 on: January 18, 2023, 12:34:10 AM »
In section 17 of the online 650 manual, it shows an electronic ignition.
Did you place the screwdriver between the pulsars or does your bike have points?

The 45* is odd.

I would time 1&4 first as in the manual (chapter3) See what happens to 2&3 (45* ?)..??
Could your advancer shaft be bent..?
« Last Edit: January 18, 2023, 12:41:48 AM by Tracksnblades1 »
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Offline Eric10024

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Re: CB 650 '81 build 99% done with an electrical/timing problem
« Reply #4 on: January 18, 2023, 12:51:01 AM »
I did the test that is presented on page 221 section 17, i placed the screwdriver between the pulsars, my ignition is identical to the one pictured in the manual. the test went well and both sets of plugs sparked.

I am afraid that the 45* is too large to be able to adjust the 1.4 point to the correct position, the pulsar ignition plate is adjustable but only so much...

I might add that during my test with the timing light, the light was consistent with plugs 2 & 3 but flashed unreliably with plugs 1 & 4, indicating that the there is not spark on every turn.


Offline Tracksnblades1

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Re: CB 650 '81 build 99% done with an electrical/timing problem
« Reply #5 on: January 18, 2023, 12:55:42 AM »
There’s a static timing example in chapter 3 page 4. You could check visually to see where it lines up with 1&4 and if 1 or 4 is on TDC compression stroke.
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Offline Eric10024

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Re: CB 650 '81 build 99% done with an electrical/timing problem
« Reply #6 on: January 18, 2023, 02:43:11 AM »
The number 1 or 4 pistons are at TDC (compression stroke) when the pulser plate markings are at 1.4 F mark, so everything seems to be ok when looking at the mechanical aspect. Is there a possibility that the 1.4 pulser generator on the pulser plate has some kind of issue?

If so is there any way to test the condition of the pulser generator?

Thank you for your input so far, its is appreciated!

Offline Flyin900

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Re: CB 650 '81 build 99% done with an electrical/timing problem
« Reply #7 on: January 18, 2023, 02:56:41 AM »
There is a test for the pulsars that should be in the FSM. I am not able to access that presently yet I have done the test in the past with a VOM. It is about reading the impedance from what I recall from 10 years ago.
Common sense.....isn't so common!

1966 CL77 - 305cc - Gentleman's Scrambler
1967 CL175K0 - Scrambler #802 engine
1972 CB350F - Candy Bacchus Olive - Super Sport
1973 CB350F - Flake Matador Red - Super Sport
1975 CB400F - Parakeet Yellow - Super Sport
1976 CB400F - Varnish Blue - Super Sport
1976 GL1000 - Goldwing Standard
1978 CB550K - Super Sport
1981 GL1100 - Goldwing Standard
1982 CM450A - Hondamatic
1982 CB900C - Custom
1983 CX650E - Eurosport
1983 CB1000C - Custom X 2 Bikes now - both restored
1983 CB1100F - Super Sport - Pristine example
1984 GL1200 - Goldwing Standard

Offline scottly

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Re: CB 650 '81 build 99% done with an electrical/timing problem
« Reply #8 on: January 18, 2023, 08:05:06 AM »
The 650 pick-up coils are polarity sensitive; notice the white band on one of the yellow and blue wires. If the wires are swapped, there will still be a spark from that pick-up, but at the wrong time.
Don't fix it if it ain't broke!
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Offline Flyin900

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Re: CB 650 '81 build 99% done with an electrical/timing problem
« Reply #9 on: January 18, 2023, 03:25:03 PM »
Here you go with the FSM testing procedures for both the spark units and the pulsars.



Common sense.....isn't so common!

1966 CL77 - 305cc - Gentleman's Scrambler
1967 CL175K0 - Scrambler #802 engine
1972 CB350F - Candy Bacchus Olive - Super Sport
1973 CB350F - Flake Matador Red - Super Sport
1975 CB400F - Parakeet Yellow - Super Sport
1976 CB400F - Varnish Blue - Super Sport
1976 GL1000 - Goldwing Standard
1978 CB550K - Super Sport
1981 GL1100 - Goldwing Standard
1982 CM450A - Hondamatic
1982 CB900C - Custom
1983 CX650E - Eurosport
1983 CB1000C - Custom X 2 Bikes now - both restored
1983 CB1100F - Super Sport - Pristine example
1984 GL1200 - Goldwing Standard

Offline grcamna2

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Re: CB 650 '81 build 99% done with an electrical/timing problem
« Reply #10 on: January 18, 2023, 04:29:24 PM »
subscribed
75' CB400F/'bunch o' parts' & 81' CB125S modded to a 'CB200S'
  I love the small ones too !
Do your BEST...nobody can take that away from you.

Offline Eric10024

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Re: CB 650 '81 build 99% done with an electrical/timing problem
« Reply #11 on: January 19, 2023, 01:41:27 AM »
Thank you @Flyin900 for the procedures!

The pulsars are both giving the same resistance (519 &520) so they seem to be ok.

The testing procedure for the spark units was a bit confusing: The instructions say to disconnect the wirings at the 4-pole pulsar generator coupler. And later in the instructions there is mention of a 6-pole coupler.

The test i did was to focus on the 4-pole coupler going up to the spark units, positive lead to the wires going to the spark units in the coupler and negative on ground (a frame bolt). The test was carried out with the ignition on and the kill-switch in "run" position.

Results: When connecting to ground the voltage rose to 3-4volts and when disconnecting ground it went to 0 volts. I tested all 4 pegs in the coupler separately. I will add some pictures as soon as i can!

I am pretty sure that i was not able to perform the tests for the spark units correctly. Any advise to the spark units test?

I can also confirm that the suggestion @scottly made earlier is not the case, the blue and yellow wires with white tape coming from the pulsar generator are connected to their corresponding blues and yellows on the other side of the 4-pole coupler. Picture of this coming aswell.



Offline Tracksnblades1

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Re: CB 650 '81 build 99% done with an electrical/timing problem
« Reply #12 on: January 19, 2023, 12:26:07 PM »
Eric,

I would further verify the polarity of the pulser causing the issue.

Scottly has indicated it can cause inaccurate ignition timing.
Which may be similar to what your experiencing.

I read you have completely rewired her with a M unit..?
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Offline Eric10024

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Re: CB 650 '81 build 99% done with an electrical/timing problem
« Reply #13 on: January 19, 2023, 01:08:45 PM »
Please see attached picture regarding the wiring from pulsar plate up to spark units. The blue and yellow wires with white tape are connected to each other i assume this is the correct way?

Yes the bike has been rewired with an m-unit but as far as the ignition system goes, everything is original.

Could a short somewhere in the ignition system cause these kinds of issues? Or could a bad ignition coil be the issue?

Please feel free to tell me if there is anything i can take a picture of to help in solving the issue.

Offline Tracksnblades1

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Re: CB 650 '81 build 99% done with an electrical/timing problem
« Reply #14 on: January 19, 2023, 02:16:20 PM »
I think I’d still verify and compare the polarity of the pulsars. Good one compared to the one in question with your VOM.

I would try to eliminate the spark unit. I’m sure it has some transistors and diodes in it somewhere..

Scottly indicated reversed polarity could cause improper timing.

Have you swapped the pulsars positions to see if your problems move to 2 & 3 ?
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Offline Tracksnblades1

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Re: CB 650 '81 build 99% done with an electrical/timing problem
« Reply #15 on: January 19, 2023, 02:32:59 PM »
Did the the engine run correctly before the rebuild ?
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Offline grcamna2

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Re: CB 650 '81 build 99% done with an electrical/timing problem
« Reply #16 on: January 19, 2023, 03:46:56 PM »
Please see attached picture regarding the wiring from pulsar plate up to spark units. The blue and yellow wires with white tape are connected to each other i assume this is the correct way?

Yes the bike has been rewired with an m-unit but as far as the ignition system goes, everything is original.

Could a short somewhere in the ignition system cause these kinds of issues? Or could a bad ignition coil be the issue?

Please feel free to tell me if there is anything i can take a picture of to help in solving the issue.

The picture of those two wires at the plug look kind of funky like they had gotten hot at some point? it's possible they might be making poor contact or shorting against each other somewhere.
75' CB400F/'bunch o' parts' & 81' CB125S modded to a 'CB200S'
  I love the small ones too !
Do your BEST...nobody can take that away from you.

Offline scottly

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Re: CB 650 '81 build 99% done with an electrical/timing problem
« Reply #17 on: January 19, 2023, 06:09:07 PM »
If you have spark, but at the wrong time, it points back to the connections from the pickup/pulsers to the spark units. The spark units should have the 6 pole connectors, and the other end of the wires from the pulsers, along with the power, ground, and coil wires, were in mating connectors in the main harness, near as I can find. How do you have the pulsers connected to the spark units? Picture, please. :)
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 Eric10024

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Re: CB 650 '81 build 99% done with an electrical/timing problem
« Reply #18 on: January 20, 2023, 01:35:18 PM »
@Tracksnblades1:

Yes the engine worked fine before the rebuild, I think you and scottly might be on the right track, one possibility is that during the rebuild the pulsar cables have been switched between each other. I had to cut the wires and re-attach them during the rebuild (look at picture 1). Tomorrow i will try switching the position of the blue cables and report back if this is the solution.

Regarding the switching of pulsars to verify if the problems switches from 1-4 to 2-3: Yes i have tried switching at the spark units and at the ignition coils, this had no positive effect.

@scottly: i hope the pictures provided give you enough information!

Thank you all for your insight so far, i appreciate all your input!

Offline scottly

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Re: CB 650 '81 build 99% done with an electrical/timing problem
« Reply #19 on: January 20, 2023, 06:27:51 PM »
Eric, you are not the first person to make the mistake of swapping the pulsar wires, and then wondering why your timing was so far off. ::)
Welcome to the forums. :)
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 Eric10024

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Re: CB 650 '81 build 99% done with an electrical/timing problem
« Reply #20 on: January 21, 2023, 08:04:26 AM »
Good news! the bike is alive on all 4 cylinders  :)

@scottly and @Tracksnblades1 were right, the polarity was reversed on the blue cables (1-4) coming from the pulsars and before the spark units.

Thank you everyone who contributed with their ideas and input!


Br,
Eric






Offline Tracksnblades1

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Re: CB 650 '81 build 99% done with an electrical/timing problem
« Reply #21 on: January 21, 2023, 10:50:27 AM »
Credit goes to the Greats…..😇

Faraday
Maxwell
Lorenz
Lenz
Hall
Scottly

😇
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