Topic: 75 CB550 K - Suddenly no spark - SUCCESS!

[Gene]

I hate when things that are not necessarily inter-related happen concurrently. 

I changed out my fuel line and added a breather hose - which this bike had never had.  No big deal I thought.  Changed out the line, clean fuel, no kinks, everyone's happy - started it up  - everything's great.  Happy Happy, Joy Joy. That was Sunday.

Monday morning, rolled it out to the street, went to kick him over - always a one, maybe two kick cold start - and nothing.  Kick, Kick, Kick, Kick (and remembered a line where a member said "It's a Honda - more than 3 kicks, pull out the tool kit") kick, kick, kick, kick (electric start button has always been non-existent) kick, kick, kick. 

Plenty of battery, all electrics work - lights, turn signals, etc. 

Checked for spark this evening - plug grounded to the head, switch on - no spark.  The only thing I can think of is the kill switch not allowing "run" as an option.  I haven't looked hard at it yet, opened the switch - nothing obvious, opened the headlight bucket - black/white connected to black/white.  I didn't have a lot of time to trouble-shoot though. (had to make 5 pie crusts for the upcoming tomato pie extravaganza).

Checked the points, pulled the plugs - all gasoline on 'em.  Checked for spark and got none. 

Am I on the right track to check the kill switch?  It's been dodgy since I got the bike, I figure I've just been lucky so far. 

Any advice is appreciated.  Let me know if you need more info to help diagnose. 

Lucky me, I have my back-up CB360G twin for a commuter.  btw - yes, this is an every-day rider.  200 + miles a week.  Usually as reliable as the street sweepers.

Thank you in advance.

[harisuluv]

No reason to suspect the kill switch first thing, unless it was a previous issue.

I think a good point to start would be to figure out if the plugs aren't sparking because they are fouled (can't spark) or are they not sparking cause the plugs are ok but something else is wrong.  One new spark plug will start you off and then point you in the right direction. 

Some bikes also won't start unless you have the clutch pulled in, so it could be related to that or the wiring.  Any reason you're using the kick start instead of the electric starter?

[seanbarney41]

Any chance you disturbed the power to the coils wireing when you did that fuel line and vent hose?

[fodzilla]

I had exactly the same issue last week! One of many issues at the moment! I'd disconnected them when dropping the carbs back in.

I'm learning fast to check connections before taking things apart!

[Gene]

Any chance you disturbed the power to the coils wireing when you did that fuel line and vent hose?

Huh.  Maybe, I didn't check that.  I will today.

No reason to suspect the kill switch first thing, unless it was a previous issue.

I think a good point to start would be to figure out if the plugs aren't sparking because they are fouled (can't spark) or are they not sparking cause the plugs are ok but something else is wrong.  One new spark plug will start you off and then point you in the right direction. 

Some bikes also won't start unless you have the clutch pulled in, so it could be related to that or the wiring.  Any reason you're using the kick start instead of the electric starter?

Thanks harisuluv, I'll try a fresh plug - I have a couple lying around. I pulled the plugs and aside from being gassy they were pretty clean.  I aired 'em off and tested outside the chamber against the head - no spark. As far as using the kick instead of the electric, since the bike has been in my possession (2+ years) it's never had a starter button so I've never used the electric.  It's never been an issue.  But, now that you mention it, that gaping hole in the control . . . I live at the beach, would it be possible the salt air corroded that kill switch?  I don't want to overthink it, first I'll check I didn't unplug the coils then I'll try a new plug.  Take it from there.

Thank you, Gentlemen

[Duanob]

The problem I've found with the 40 year old honda is the plastic terminal/ keepers inside the kill switch are brittle and can break. Both my 550s required new righthand controls because of faulty kill switch internals.

[Gene]

Thanks Cal and Duanob,  I was gonna check a new plug just for the spark.  I'm not proud of it, but I've run on 3 cylinders to get home before  I'll test the voltage and clean the connector up if it's crusted in there.  Took a quick peek yesterday and nothing obvious, not like when a voltage regulator gets all crusty (62 Cadillac - great car, horrible car).  I may try to swap my right hand controls from my 360 to the 550 just for the interim - are those interchangeable?  They sure look the same - I'll check that out before I do anything rash.

Thank you again, all. 

[flybox1]

I had exactly the same issue last week! One of many issues at the moment! I'd disconnected them when dropping the carbs back in.

I'm learning fast to check connections before taking things apart!

+1
check all connectors under the tank and near the coils

[carnivorous chicken]

Easiest thing to do is to trace the BLK/WHT wire from the KILL/RUN switch with the switch set to RauN and verify that you have 12v. Then, repeat this at the coils where the BLK/WHT wires attach. If 12v is not present, then you aren't going anywhere.

A single fouled plug will not prevent these bikes from starting. Will they run right? No, but they will start, idle rough, and run like crap, but they will start.

And yes, definitely, salt air will corrode the switch contacts on your handlebar very quickly. One day it will work, the next, not. Corrosion accumulates to the point where after enough time it prevents the electrical circuit from completing. End of story until is cleaned away. If you find this to be your problem, carefully split the switch housing, and remove the green corrosion from the contacts underneath completely. Buy some aerosol Electric contact cleaner, some dielectric grease, and clean it. Then lightly cover the contacts with DI grease to help prevent its return.

This. I'm assuming you lost all four cylinders at once (or at least checked 1 or 4 and 2 or 3). Bad ignition point or jumbled wires or bad coil would only cause 2-3 or 1-4 not to work -- too much of a coincidence that all 4 would go out at once. Check that kill switch, sounds like it's been sketchy. BTW, I've had the kill switch be a culprit in the past...

[Gene]

This. I'm assuming you lost all four cylinders at once (or at least checked 1 or 4 and 2 or 3).

Yes - I checked 3 & 4.  Looked at the connections, all are good.  I swear, it's the switch.

I had exactly the same issue last week! One of many issues at the moment! I'd disconnected them when dropping the carbs back in.

I'm learning fast to check connections before taking things apart!

+1
check all connectors under the tank and near the coils

That's a handy tip to keep in mind tho, easy to shove that tank on and pull something loose.  Never even crossed my mind.

Cal, I checked the voltage at the coils of the B/W, where it splits to 2 wires (1 to each coil).  It could be me not knowing how to read a multi-meter, THIS IS A DISTINCT POSSIBILITY, my wife is the engineer of the family, but I was getting various readings anywhere between 2.3 and 6.5.  Again, I'll ask the expert to see if I was doing it correctly . . . BECAUSE, it seems I have nothing but time on this chasing down this lack of spark.

Know why?  Ask me why . .. ok, I'll tell ya.  Cuz the friggin pull cable for the throttle snapped right off - broke about 8 inches off the grip down in the cover.  It was completely rusted and just snapped like an old rubber band.  So I'll be ordering both a pull and a push since I can't tell how horrible the push is inside.  Feh.

So, at least I have time to study how to attach and read a meter correctly.  Still have plenty of battery, that much I know. 

I can't help but think all signs point to that switch which, as I said originally, was always a little dodgy.  I know it's inappropriate, but why couldn't I just bridge where the switch is and do away with the "kill" option entirely?  I've never used it, and I know it's a safety feature, but is it absolutely necessary?

Seriously, thank you all for the input.  When I get to the bottom of it all I'll mark this "RESOLVED" and type up a synopsis.  This bike hates summertime, last year it was the carbs.  At some point, though, it'll have all new parts!

[Gene]

Can't thank you enough Cal, I don't know much about electrical, or how to test it.  Your instructions are clear, I understand it better now. Digital, btw.

Should have looked those cables over before now - hell, the bike's 40 years old.  Just had it's birthday!  I will be sure to lube the cable (wait, is this a family-friendly site?) prior to insertion. 

Again, thanks to everyone.  I'll update once complete. 

p.s. - the bypass of the kill switch is off the table.  My dear wife simply won't allow it. "If it's stock, keep it stock!  No mods."  Paraphrased.

[Duanob]

  My dear wife simply won't allow it. "If it's stock, keep it stock!  No mods."  Paraphrased.

If that's the bike in your avatar I'm on your wife's side! Nice looking 550K in Sunburst Orange.

You can get a wiring diagram from this website and just start following wires and testing with the multi-meter on vDC setting. I had a headlight go out once with no voltage to it. I traced it back to the kill switch that had crumbled on the inside. New control switch and all is good. But your looking at around $100 and it will be similar to original but the kill switch button is a funky purple color instead of red. They are made in china these days. Most people will never notice (but we will!)

[Gene]

Duanob - yeah, that's my O.B.  Great bike.  Got it from the actual original owner - tho via his nephew (who did some unsavory things - for another thread).  Original CA pink slip, when they used to actually be pink. Also - funnily enough I already have the original wiring diagram - that's what I've used to chase down a few problems.

To update - Cal - My wife the engineer says I did it right (tho I'll do it again) - grounded to the center bar, clipped on the B/W, varying voltage.  She explained it as "think of it like it's water . . . there's a clog in the electricity."  Which is what I think - but again, one more reading tomorrow in the daylight (no garage) to make sure.

PARTS!
Ok - I have found these.  Duanob, Is this the switch to which you are referring?  This vendor says it fits a 76 550K, makes me a little nervous, but a search and the price makes me think it's about right.  Everything else I've seen (and bought) has fit the 72-76 series K's.
http://4into1.com/genuine-honda-throttle-switch-assembly-35130-377-p00-cb360-cb450-cb500-cb550-cb750/

or? (maybe a cheap-a$$ replacement?)

http://www.z1parts.net/product/honda-cb750-cb550-switch-kit-main-35010-374-671-contol-switch

And in general, I'm having trouble finding the OEM Push AND Pull throttle cable (even at David Silver, who I though had EVERYTHING), and I've decided I may as well replace the clutch cable while I'm at it.

OPINIONS on the following Cable set?  I've seen the brand name - dunno if it sucks or is a good replacement.

http://4into1.com/motion-pro-control-cable-set-honda-cb550-cb750-early/

btw - my rudimentary knowledge of hot-wiring makes me think that if I clipped the black/black-white wire at the switch and wrapped them together, achieving 12V at the coils, that would prove my theory - right? Unfortunately, if it did not prove it, then I would have clipped the wires for nothing.  Would that be correct?

Opinions are encouraged, You have all been so helpful and supportive.

On an aside, harisuluv - at some point when I can put O.B. in a sit/stay for a while, I need to send you my carbs for a real treat, just so I can know what they're capable of. 

Gene

[Gene]

Good advice.  I'll take it.  I've done some tracing/cleaning/verifying connections but you're right - good a time as any to go through the whole thing.

[Gene]

Gene - your meter (if analog) should have a dial where to set the a Voltage range, use 0-20v. Touch the Black probe to a good, known ground point on the chassis (like maybe where the horn mounts to the frame. Attach the Red probe into the bullet connector of the BLK/WHT. Keep good contact on both probes. You should get an accurate reading.

If it's a digital. Set to Voltage and repeat the same above. Then, set to Ohms and check the resistance of that wire. This would be a reading on the corrosion interrupting the current (voltage) from being passed. It should be a very low resistance reading, like less than 1.0 Ohm.

I'm getting a reading of somewhere along the lines of nothing - w/the V - .002 etc.  Ohms, yes, same thing, less than 1.  I haven't done a straight-up test on the coils themselves but will.  One thing at a time.  Also going to do a nice thorough investigation through the 'lectric system while waiting for stuff.

Speaking of which, I haven't ordered anything yet - waiting on feedback. This is NOT in my nature, usually I just get what I think I need and 90% of the time I'm right.  I'm trying to learn patience. 

Are after-market run switches as good as anything else?  I would think with electrics more modern is better, but I know these bikes are sensitive.

Anyhoo - talk soon, gotta make some pasta.

[Gene]

Thank you all for the tips, information and suggestions.  While I waited to get the switch in (ordered the wrong one the first time) I went through all the connections, cleaned, dilectic greased and realigned wires so it wasn't such a rat's nest, got new throttle and clutch cables, 4 new NGK plugs for good measure, and basically waited until I had time install everything.

I disconnected the old run switch and plugged in the new before I ran it through the bars - voila, a reading, tho low because by this time the battery was half-juiced.  Swapped out the battery with my 360 which I new was charged (and will start with almost zero charge on the battery - that bike is a miracle).  Readings good, ran the string through the bars, plugged it all back together, ran and installed new throttle and clutch cables, fresh plugs, checked plug wires and caps, checked for spark - and there it was. 

Hooked it all up and it took a while but O.B. finally came to life. Runs better than it ever has and I don't have to worry that the clutch cable will snap mid-ride.  That whole electric-start thing is new to this bike, didn't even know if the starter worked, but it certainly does.

Again, thank you all.  I haven't done a lot of this stuff.  I've done carbs, sprockets and chain, some electrical chasing, but not to this degree.  Learned a bunch and am more confident in the bike than before.

Rode it to work today - 20 mile 1 way commute, nothing blew up and nothing fell off.  It's a good day.

[djoz371]

So here we are in 2020 and I am dealing with the same issue on my 73 cb500. Did a search and found this thread. Glad to see the Gene got it sorted out and I am thinking I have the same solution. Part ordered and thanks for this!

[Gene]

Hope it worked out.