Topic: 75 CB550 K - Dead cylinder #3 & 4- fixed 2nd and final(?) time.

[my name is nobody]

If not solved by Monday, I plan to start a  Go Fund Me acct to fly Cal out to Cali to address!

Gracious of you, Stev-o. And please, dear members who live in, and like California, take no personal offense; but there ain't enough money in this hemisphere to get me aboard an airplane to land in California. Personal issue. Anywhere else, love to help.

BTW - I only added the reference to checking coils, but with the issue on 2 separate cylinders served by 2 coils, the odds are mathematically lower that I would fly to California than this being your problem. Just saying.

cal, to re word a bit, could one malfunctioning coil have an adverse effect on the good opposite coil due to the fact that they share a common power source? Like if one had an intermittant short? Just to compare, I once saw similar behavior between 2 fuel injectors that shared the same power source.

[Remcod]

Swap sparkplug 3 and 1 to rule a faulty plug out

[calj737]

cal, to re word a bit, could one malfunctioning coil have an adverse effect on the good opposite coil due to the fact that they share a common power source? Like if one had an intermittant short? Just to compare, I once saw similar behavior between 2 fuel injectors that shared the same power source.

If the inbound BLK/WHT wire (which carries 12v from KILL/RUN) were flaky, its possible that the coils would misbehave. But, to only misbehave in those 2 cylinders despite all else? Odds are long. You can certainly check the power with a meter, and the resistance too to rule things out.

[RAFster122s]

Is it possible that the spark is not able to build enough for firing when # 3 and 4 are reaching points opening?  I would expect bad coils to exhibit intermittent failure on both cylinders and even rougher running than is being seen.  Sounds like you need to check compression on 3&4.
You report spark.  Inductive timing light clipped on near plugs can confirm spark is going to caps.
you do have two outlets on the coils but your swapping the connections from points and reversing the plug connections on both coils kind of eliminates that issue if swapping 1&4 does not change running behavior.
Broken cam shaft would not allow you to set the valves for those cylinders, as remote as that would be possible.
Washing down the oil with gas is really not doing the lubrication for any cylinder any good.
May want to buy a cellphone/computer boroscope off ebay.  Longer versions can be  more useful for more things, fwiw.

David

[Gene]

BTW - I only added the reference to checking coils, but with the issue on 2 separate cylinders served by 2 coils, the odds are mathematically lower that I would fly to California than this being your problem. Just saying.

Right - it would be an oddity like no other were it the coils. Especially since the firing remained on 1 & 2 when I swapped sides w/the leads.

Either way, back at it tomorrow. As a distraction until then, here are my Nephew's sons on the 750.

[palepainter]

I recently experienced similar.  It wasn't that they weren't firing.  They got too much gas and fouled the plug and cylinder. 


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[Gene]

I recently experienced similar.  It wasn't that they weren't firing.  They got too much gas and fouled the plug and cylinder. 


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Yes - I tried brand new plugs as well - checked for spark etc. Will take a harder look again this weekend. Fixed by Monday or nailed to the wall and called "Art". (jk)

[scottly]

Gene, just to rule the coils out, would you consider temporarily swapping the 750 coils onto the 550? PITA, I know, but electrically they are the same.

[scottly]

An afterthought: with the wasted spark ignition systems, the spark on 3 and 4 are reverse polarity, and weaker than 1 and 2. It's the nature of the beast. Measure the voltage at the black/white junction at the coils; if it is low, it may still allow 1/2 to fire, but not 3/4.

[Gene]

An afterthought: with the wasted spark ignition systems, the spark on 3 and 4 are reverse polarity, and weaker than 1 and 2. It's the nature of the beast. Measure the voltage at the black/white junction at the coils; if it is low, it may still allow 1/2 to fire, but not 3/4.

I'll check. Thank you. Didn't know that.

[Gene]

Gene, just to rule the coils out, would you consider temporarily swapping the 750 coils onto the 550? PITA, I know, but electrically they are the same.

If we get to that point I may try it.

Just reading through again before I get my hands dirty.

[Gene]

Battery's still reading 12.45 at rest, but frankly, I think it's not very "live" judging by the neutral idiot light test. Very weak.

B/W at the coils, I'm getting readings of 7+, not 12. Key on, run position. Connections were good but cleaning, dialectic too.

Is this just the m-fn battery? Pulling and charging, tho the tender shows green.

Back in a bit.  Will do the clear tube test today too. Just cuz.

Actually, pulled the battery off the charger when I checked and it read 13. Makes me nervous and this is a gel battery-me using a wet-cell tender. Don't want it to melt.

Trying to see if I can get a better read off the B/W. I may not be grounding it properly. Also changing the 9V in the meter.

[b52bombardier1]

A 12.45 volt reading on a battery is only half of its health. Can it deliver many amps? Only a load test at an auto parts store can answer that question.

Rick

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[Gene]

A 12.45 volt reading on a battery is only half of its health. Can it deliver many amps? Only a load test at an auto parts store can answer that question.

Rick

Sent from my SAMSUNG-SM-N900A using Tapatalk

Yeah, and it's brand f-in new. I know that means nothing. Wish I'd saved the Yuasa.

[calj737]

Battery's still reading 12.45 at rest, but frankly, I think it's not very "live" judging by the neutral idiot light test. Very weak.

B/W at the coils, I'm getting readings of 7+, not 12. Key on, run position. Connections were good but cleaning, dialectic too.

Battery is weak, and 7v at coils is a significant problem.

[Jimray23]

Did u use dielectric on the bullet connectors for the coils? If so did u aply it before or after they were plugged in? Either way u should test both sides of the connectors.

Jimmy
1979 kz1000 ltd

[Gene]

Battery is weak, and 7v at coils is a significant problem.

Yes, one would think, if the user had proper knowledge of how to use the damned thing.

[Gene]

I'll probably drop #3 just to make sure everything is in place correctly.  Get back to all on that.
 
Hint.

[Gene]

It's the carbs - gotta be. It's been 3-4 years since I've pulled, inspected, cleaned. I'm hoping it's that simple. 

Thank you all so far for your suggestions and checking in.

Hint 2 - wait for it. You'll laugh your ass off.

[Gene]

dammit. #3 bowl, as it came off.

[FIREBLADE74]

First post!

I'm having the same problem on a 76 550SS, 6800 mi. Except its cylinder 1 that won't get fire, got spark, and fuel in the bowl.

Hope you get it sorted and let us know how.   

[Gene]

H*ckin jet just hanging out, having a party.  BTW - put back in - bike is happy as can be. Question is - why. Did I get distracted the last time I was cleaning the jets, only screwed it in hand tight, forgot, put the bowls back on? Is it going to be a recurring issue? Threads not holding? They're not stripped or crossed - went back in easy as pie.

I should have listened to my gut.

Cal - you're right, 7 is a serious problem but I'm so goddamned stupid with a meter I'm sure that reading was wrong. Everyone else who chimed in gave good advice as well. And I appreciate it. But apparently I'm too stupid to listen to my own, which I told my neighbor, that "I bet I pull a bowl off and there's a gorram jet sitting in it."

For anyone else, if you think you have an idea as to what the issue may be, follow it through first. It doesn't need to be reported, but look. I have dragged members into this that I respect and now I come back with a simple, stupid solution because I didn't take the time to drop that bowl and find the real problem.

I'm not saying it's bad, I'm just saying their time could be used on real problems more effectively.

To all who have commented, I do appreciate it, even you Cal. If I have wasted your time, I apologize- profusely. Have I said that enough?

Now, the real question is, why was it sitting in the bowl? Perhaps I got distracted after a quick finger-tighten. Perhaps I didn't even have it in the right spot, but it didn't fall down because it was held there by tension. Perhaps there is an issue with the threads themselves and the jet can work it's way out (I don't think this is it).

Anyway - going to do a short but reasonable run tomorrow - 20-30 miles - make sure it's solid. For now, I feel semi-confident. Took it for a spin around town. Lots of stops and starts, seems to be right.

I'll close this tomorrow if the longer run works out.

I can't say this enough - thank you and apologies if I have wasted your time.

[Gene]

Did u use dielectric on the bullet connectors for the coils? If so did u aply it before or after they were plugged in? Either way u should test both sides of the connectors.

Jimmy
1979 kz1000 ltd

threw it on before I slammed 'em back in. On the male, like lube.

[Stev-o]

Glad you found it!  There are many instances when what appears to be a major problem is an easy fix that was overlooked.  Did you check the others?

[calj737]

Glad you sorted the problem out. The only person who wastes my time is me. I invest it into things that appeal to me. Trying to help people appeals to me. Sometimes I do, lots of times I don't. But it still is an appealing challenge.

The only reason I linger on some threads like this is due to the evil curiosity to know the remedy. That's all. I file it all away for use another time, another day. This forum offers much to many. For me, its a great big cauldron of learning soup.