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

[Gene]

Do u have 1 or 2 fuel lines coming from the tank to the carb? The reason i ask is, if u have 2, the line going to cylinders 3- 4 maybe restricted. If so the carbs will still fill but not fast enough to keep those cylinders firing. Once u stop the carbs will fill up and look normal.

Jimmy - my gosh you may be onto something here. I did just replace my fuel lines, dual output petcock, and I even broke one of my own rules and used a needle-nose pliers to shove it on the nipple at the carbs. I'll check. Friggin' genius and easy.

While I'm at it, as Strynboen has reminded me , I'm fatally lazy and the tank could use a cleaning as well as the petcock and filter.

Raf, good ideas and I'll see if I can duplicate the problem on the other side (1 & 2). I'll also check the coil readings as suggested.  Plug caps were all tested "off".  And - you're right, most carb problems are electrical. I learned that from this forum. - btw, I have brand new boots I've been meaning to put on anyway - could be a good excuse to do so.

And THIS, ladies and gentlemen, is why I love this forum and all who reside therein. The give and take of information. I can only hope that one day I am knowledgeable enough to give advice that helps.

I'll update when I have a chance to get at it - probably not until Sunday the 19th the way things are looking now, but I will follow up.

Thanks again,
Gene

[Stev-o]

Hey Gene.....cannot offer additional help but you may be onto something with the fuel lines.  I experienced a similar problem with my 550...was running great one day and then died.  I had lifted the tank to replace the tach cable and the fuel line got pinched when I put the tank back in place.  Simple fix.  Hope yours is too.

[Gene]

Hey Gene.....cannot offer additional help but you may be onto something with the fuel lines.  I experienced a similar problem with my 550...was running great one day and then died.  I had lifted the tank to replace the tach cable and the fuel line got pinched when I put the tank back in place.  Simple fix.  Hope yours is too.

This is my hope.

[Scott S]

 Check the vent hose for the 3/4 carbs. Are those bowls running empty because of a problem with the vent, maybe?

[my name is nobody]

the 3 and 4 carbs share the same bowl vent. Make sure the inner vent port in each carb
 and the 90 degree elbow and vent hose on #3 are all clear if you take the carbs off. Also, do the clear tube test with the engine running. Get an assistant to help watch for leaks/safety. USE GOOD JUDGEMENT. May be that fuel levels are varying (high or low, most likely hi) beyond correct limits due to a float sticking, while the engine is running. This condition would make the engine run flaky, then better, (after you rev it to clear it out) then
get worse etc./ in irregular cycles. The float must be able to MAINTAIN the PROPER level of the fuel in the bowl under ALL conditions. If it's flooding on any cylinder, then straightening
itself out briefly,/repeat, you can't see that happening unless you watch the level in the
tube. You can chase your tail if this is the case. And if it's flooding a cylinder enough, it'll wet foul a plug. I'd also check the oil and make sure it's not over full and/or contaminated with gasoline, and that there is no raw fuel coming out the exhaust of suspect cylinders. This is my theory, I don't
know it all, and if anyone can prove this theory wrong, Please do so.

Edit:  check the obvious stuff first as previously suggested. After re reading this seems a
little extreme but the test might help if you can't find anything else. vac leaks etc.

[Duanob]

BINGO on the fuel lines. Pull the lines off the fuel tap and with a bowl under neath open it up to check for flow. If it's good there then you might have a plugged fuel line to the 3&4 carbs. Do you have an inline filter that's maybe lugged? Is there a point in the line where is goes up instead of down? Being gravity fed there isn't a lot of fuel pressure to feed the carbs. Also, is there enough fuel in the tank? I ask this because I had the same thing happen to me when I first got my 550. I put a couple of gallons in the tank thinking that was enough. I went through everything, 3000 mile tune up, carb cleaning, etc. Still had troubles with the 3&4 getting hot. I checked the flow and it wasn't getting much out of one tap tube to the far carbs. I threw another gallon of gas and it sparked right up. I also took the intank filter out and cleaned it and that helped a lot too as the filter tends to get clogged from the bottom up. 

[Gene]

Thanks again gents.  If all goes well I'll at least check the fuel line, petcock flow and vent tonight.  Full tank of gas right now - will definitely do the "sock" cleaning etc. when time allows.  One thing at a time and we'll see, yeah? "Start with the easy stuff".

I'll let you know.

Update - won't have time tonight. If I "flow" any gasoline inside the garage I will be shot on sight. It'll need to wait until Saturday morning. Very much looking forward to seeing if this is an easy fix.

Another p.s. - no in-line filters. I don't have a strong opinion on them, unlike some others here, but I figure it's my luck they'll just leak.

Last p.s. - Nobody, I'm not sure I have any judgement left, good or otherwise

[Gene]

Well, sh*t.  Petcock flow is good, line is clear. Can't get at the vents really unless I take off the carbs. Just a quick eval. Started up on second kick after putting it all together (just for yucks) - same result. 1 & 2 firing, 3 & 4 not.

Pulled the plugs, wet. Dried, cleaned, tried again, same result. No change in the pics above (re: plugs), btw.

So, tomorrow, moving on I suppose. Truth is, at this point I oughta pull the damned carbs and send 'em to harisuluv for a going-through. It can't hurt and, as I've said repeatedly, I'm an accountant with a wrench. Doing my best, but sh*t. Have a real pro work on it. At least we know where we stand, right?

Anyway, great ideas so far guys, and I'll keep plugging away. I miss my 550.

Adios for now.

[scottly]

Well, sh*t.  Petcock flow is good, line is clear. Can't get at the vents really unless I take off the carbs. Just a quick eval. Started up on second kick after putting it all together (just for yucks) - same result. 1 & 2 firing, 3 & 4 not.

Pulled the plugs, wet. Dried, cleaned, tried again, same result. No change in the pics above (re: plugs), btw.

If there was insufficient fuel flow, the plugs wouldn't be wet. If there was too much fuel, the plugs would be black. Try putting two brand new plugs into 3&4 and try again. If the cylinders still aren't firing, pull the new plugs and inspect them. If they are clean, but wet, it indicates either a lack of spark at the right time, or possibly a lack of compression; seems one of the changes before this issue started was dealing with the top end and valve adjustment?

[my name is nobody]

Well, sh*t.  Petcock flow is good, line is clear. Can't get at the vents really unless I take off the carbs. Just a quick eval. Started up on second kick after putting it all together (just for yucks) - same result. 1 & 2 firing, 3 & 4 not.

Pulled the plugs, wet. Dried, cleaned, tried again, same result. No change in the pics above (re: plugs), btw.

So, tomorrow, moving on I suppose. Truth is, at this point I oughta pull the damned carbs and send 'em to harisuluv for a going-through. It can't hurt and, as I've said repeatedly, I'm an accountant with a wrench. Doing my best, but sh*t. Have a real pro work on it. At least we know where we stand, right?

Anyway, great ideas so far guys, and I'll keep plugging away. I miss my 550.

Adios for now.

Gene
These are the same results you stated in reply #10 of this thread. I base(ed) my sugestion
earlier on these same symptoms you're describing. In your earlier reply you mentioned
gas pissing from the carb overflows. Does this occur now as well? Is there still spark? If a carb or two are
flooding quick enough, maybe just before start up even, the plugs for suspect cylinder(s)
can get wet fouled, and stay that way unless the carb stops flooding. You can determine
if any are flooding with the clear tube method. This is an interesting thread, it will be
interesting to find a cause. Respectfuly, I don''t mean to start a sparring contest with
anyone, and appreciate your frustration. The answer is here somewhere
and +1 on replacing 3-4 plugs.

[strynboen]

i had drovned mine once the coils vas a bit bad..heated the plugs..use a gas burner..and throv the hot plugs in the bike..and it startet ..and run all cylenders ..and after that it just keep running..it vas just a kombination of vet plugs and dirty carbs(rust in the tank)..and bad heighvolt kabels  at the coils...but 3 problems gave nr 4 as vas a drovned engine..so symptoms can be..thanging on going..the vet plugs vas not real fuel related..it vas a symptom of more different problems fighting at the same time..heating the plugs vill make them stay more dry at first start try..blow kompressed air to the plug holes can also dry up

[Jimray23]

Take the 1- 2 spark plugs and put them in place of the 3- 4. That will tell u if its the plugs.

Jimmy
1979 kz1000 ltd mkii
     dyna s ignition, dyna 3 ohm coils, solid copper core plugs, full rewire.

[Gene]

Scott, Nobody, Stryn and Jim. Thank you.

Scott & Jim, I'll try new plugs - see what gives. Fact is when I bought the bike there was no fire in #4. Replaced the plug, problem gone. Hopefully the same thing here, yeah?

Also going to to swap leads, see if the problem goes to 1 & 2. Could be a bad coil. Rare, sure, but it can happen, right? I don't think that's it, but what the hell.

Nobody, you're absolutely right. Same symptoms, same issues. Got a little pissing from overflows but while on the bike it's impossible to tell from which cylinders (?). You are absolutely right I need to do the clear tube with all carbs - and will. Maybe not until the 19th though (time allowing).

Strynboen, I have a torch. Maybe I give 'em a flame and all is fine? Sounds nice and easy - I'll give it shot, but I can't help but think it's more than that (?).

Again, thank fellas, I'll update when I have more info.

[Scott S]

 Are you running points and condensers? I had a similar issue recently on a 350 twin and the condensers were shot and giving out once they got hot. Let it sit and runs like new....for a minute.
 Also check your plug cap resistance. Maybe trim back the wires a mm or two, install new caps and new plugs. Once plugs have been fouled a few times, they're never right again.

 Somebody once told me that 90% of all carb problems are electrical.

[calj737]

Are you running points and condensers? I had a similar issue recently on a 350 twin and the condensers were shot and giving out once they got hot. Let it sit and runs like new....for a minute.
 Also check your plug cap resistance. Maybe trim back the wires a mm or two, install new caps and new plugs. Once plugs have been fouled a few times, they're never right again.

 Somebody once told me that 90% of all carb problems are electrical.

Almost every bit of advice has been given, at least twice. Gene, you need to pull plugs and post pictures of them. Scottly (and I) asked the condition of the plugs (wet, black and wet, etc) and theres been no reply. You seem determined to fault the fuel, yet you have not performed a comprehensive spark test.

Round and round you go after your tail.

[Gene]

Are you running points and condensers? I had a similar issue recently on a 350 twin and the condensers were shot and giving out once they got hot. Let it sit and runs like new....for a minute.
 Also check your plug cap resistance. Maybe trim back the wires a mm or two, install new caps and new plugs. Once plugs have been fouled a few times, they're never right again.

 Somebody once told me that 90% of all carb problems are electrical.

Almost every bit of advice has been given, at least twice. Gene, you need to pull plugs and post pictures of them. Scottly (and I) asked the condition of the plugs (wet, black and wet, etc) and theres been no reply. You seem determined to fault the fuel, yet you have not performed a comprehensive spark test.

Round and round you go after your tail.

Plug pics were posted earlier. I will do it again. They keep looking exactly the same. What I need to try is new plugs as was suggested. Just haven't gotten there. More pics and less me chasing my tail

[Stev-o]

Are you running points and condensers? I had a similar issue recently on a 350 twin and the condensers were shot and giving out once they got hot. Let it sit and runs like new....for a minute.
 Also check your plug cap resistance. Maybe trim back the wires a mm or two, install new caps and new plugs. Once plugs have been fouled a few times, they're never right again.

 Somebody once told me that 90% of all carb problems are electrical.

Almost every bit of advice has been given, at least twice. Gene, you need to pull plugs and post pictures of them. Scottly (and I) asked the condition of the plugs (wet, black and wet, etc) and theres been no reply. You seem determined to fault the fuel, yet you have not performed a comprehensive spark test.

Round and round you go after your tail.

Plug pics were posted earlier. I will do it again. They keep looking exactly the same. What I need to try is new plugs as was suggested. Just haven't gotten there. More pics and less me chasing my tail

We are getting impatient!  Need me to send you some plugs?!
Surely you can afford $1.69 a plug...

http://www.jegs.com/i/NGK-Spark-Plugs/739/D7EA/10002/-1?CAWELAID=230006180000225891&CAGPSPN=pla&CAAGID=15769068431&CATCI=aud-194671897271:pla-224825142071&CATARGETID=230006180037474308&cadevice=c&gclid=CjwKEAjwqZ7GBRC1srKSv9TV_iwSJADKTjaDB4WK5U164tiow3pqkQHuoy09_ACNapO3MV5nWpHYnRoCa2Hw_wcB

[Gene]

Sorry -  I can afford plugs but I don't have the actual time to do anything on the bike until Sunday. Rehearsal, work, gig, and a trip to San Diego between now and then.

At that time I will update. Gonna replace plugs - check for spark first - rule out bad caps/wires. I did that already and there was spark. Checked all the caps, caps off, readings between 5-6. Will check again tho. Try to run. If a fail, put my old condensers back on. Try again. If a fail take it from there.

And Cal - I only wanted it to be fuel - cuz that was fast and easy to check. Plugs are too, sure, but - ah hell . . . time is something I don't have much of right now is all.

[Gene]

OK - had some time today. Had a stock of brand new plugs anyway - here's what we did.

Checked Plug caps for 3 & 4. 4.97 and 4.92 respectively. Caps off.

Battery reads  12.45 resting.

Plug pics - there are how they look after I pulled 3 &4 - from the left. Smelled gassy, looked  a little wet. (the pics will be below in order since I'm too stupid to figure out how to put them within the dialogue).

Checked for spark on 3 & 4, plug resting against the head as a ground, Kick start, 3 & 4. Had verified spark. Even from my neighbor the hot-rod guy who stopped by to check up on me. 3rd party verification of spark for 3 & 4. If I'm sounding  repetitive it is just to remove any question of what I have or have not done. Scientific method.

I have brand new plugs. Installed and had the same situation - ! & 2 running, 3 & 4 not. Headers slightly warm, mufflers stone cold. Compression coming out of all 4, but, again, 3 & 4 cold.

Moved wires 3 & 4 to 2 & 1 respectively to see if I could mimic the situation (1 & 2 dead, 3 & 4 firing). No start at all. Not even a little firing. I should do this again to double-check, making sure fuel, connection (#3 plug wire is really short now) are all in spec, but got no fire at all. AGAIN, tested spark on 3 & 4 previously and saw spark.

I replaced the new condensers with the old ones. I have not yet replaced the new points with the old ones. That may be it but I'm running it by you cats first.

I also pulled the #4 plug after this test. Smelled gassy but not fouled. Pic attached below with the rest.

To recap: 1 & 2 firing normally, 3 & 4 no fire. Spark is assured, fuel is getting to the cylinder. Static timing has been done BUT I am not a helluva mechanic so is my testing way the hell off? Set the points according to the manual, have been setting points for years now (just as a reference), the light comes on close to where it should.

Could it be a situation where the timing is 180 degrees off? I don't think so but then again - not a pro.

Advice is welcome. Cal, if I have f**ked up along here somewhere let me know, you're giving me sh*t but damn, I think I'm following protocol. If not, bring it. I need to fix this.
It seems as though there is fire but maybe not enough (?) to get the process going. At this point am I looking at coils? Carbs? Fuel? Gentlemen, I seem lost on this.

Also, a pic of the battery I bought. Is this sh*t? Just curious.

Thank you all,

Gene

[scottly]

I'm guessing that the 3 & 4 spark plug wires are swapped? The 2/3 plugs are fed from the same coil, so if 2 is firing, 3 should be also, and the same for the 1/4 pair.

[Brian G]

I've been following this thread for a while with great interest - it could be me, someday - and I can certainly sense your rising frustration level. I wish I had some technical advice but everything I can think of has already been suggested other than maybe a problem with voltage supply to both coils or that we may be looking at two simultaneous problems.

The other thing is that we shouldn't forget your posting on Feb. 25 which noted 'she ran like a champ'. On startup two days later, the problem(s) began. Unless the plug leads changed over and/or the timing set itself 180 degrees out by itself, we need to focus on what happened (or got worse) during that two day shutdown.

I wish I could be of more help. I'm pulling for you!

Regards,

[Gene]

I'm guessing that the 3 & 4 spark plug wires are swapped? The 2/3 plugs are fed from the same coil, so if 2 is firing, 3 should be also, and the same for the 1/4 pair.

Right? The leads are actually numbered so I don't do that by accident. Having slept on it I'm going to do some reading. I know I'm just missing something, probably something simple.  Re-read this thread too and the advice given.  Tick off the boxes and see what I've missed. At least this time I had a witness watching me so I didn't forget something.

Thanks again guys, I need to study.

[Deltarider]

I don't know if I put the condenser wires on properly

As long as their spade connectors only contact the little bolt of the breakerpoint (and so resp. the blue and yellow wire that go to the coil -) and NOT make ground. This is easily checked.

[Gene]

I don't know if I put the condenser wires on properly

As long as their spade connectors only contact the little bolt of the breakerpoint and NOT make ground.

Will check tonight.  Thank you.

[Deltarider]

This is easily checked.

Do a simple test with the ignition off. First, have some plastic, business card or whatever between both sets of breakerpoints (left, 1+4 as well as right, 2+3) so both sets are isolated (both are open as it were). Then hold one probe of your ohmmeter against the spade connectors at breakerpoint 1+4 and the other against the groundplate and see if these spade connectors accidentely ground. Repeat with 2+3. Please report back.