Topic: New Member - 1978 CB550 carb sync issue. Lean now, and #2 cyl not firing.

[DaveBarbier]

The screws will be tough to get at the first time. With built up varnish they can be pretty stubborn. I'd spray some penetrant and let it sit for a bit. Use a nice fitting JIS driver and with some decent pressure they'll come out.

After removing the slides a resync will be required. Bench sync using the drill bit method and then finish with a vacuum sync on a fully warmed up motor.

All slides seem to be oriented properly, so that's not an issue. But all that orange/red RTV looking sealant doesn't inspire confidence. Keep that RTV stuff far away from your carbs!

[Calvin]

The screws will be tough to get at the first time. With built up varnish they can be pretty stubborn. I'd spray some penetrant and let it sit for a bit. Use a nice fitting JIS driver and with some decent pressure they'll come out.

After removing the slides a resync will be required. Bench sync using the drill bit method and then finish with a vacuum sync on a fully warmed up motor.

All slides seem to be oriented properly, so that's not an issue. But all that orange/red RTV looking sealant doesn't inspire confidence. Keep that RTV stuff far away from your carbs!

Understandable.  So just to be clear.... what are we even troubleshooting at this point?

Overall, the bike is running lean, so that's my reasoning to get in there and adjust the needle clip settings.  But, I still have intermittent firing of the #2 cylinder at idle.... wouldn't this be unrelated to the pilot jets, when the throttle isn't twisted at all.  That issue is bothering me way more than the small pops and backfires i get while coasting.   


If I have shown that idle jets are clear, than what else can be done to troubleshoot this specific issue?
Looking back at the spark plug pictures with a fresh set and a plug chop, it looked like 2 and 3 almost were identical, either very lean, or not even firing all the time.

[Calvin]

I was looking over at the 77-78 PD46C carbs FAQ again to ensure I have done everything in the first post there to make sure they are clean and setup. 

A lot of people seem to be running a bigger idle jet with the #45 instead of stock #42.  Any thoughts on this?  I feel like with my pods and straight pipes it could use a bigger idle jet possibly

[flybox1]

Try this...might help you verify bigger pilots are indeed needed.
Wrap tape around your #2 pod filter so 50% of the material is blocked.
Start the bike and see if #2 kicks in during idle.  Yes? No?
IF NOT...slowly turn your #2 IMS richer.  Did help #2 join the idle party?

[DaveBarbier]

I was under impression that you were going to verify the needle height.

I'm no expert but I was thinking you'd want to try and get all firing and the plugs all equal in color before attempting to jet for your intake/exhaust setup.

I haven't been following along from the beginning, just popping in so I wasn't aware that you had pods and straight pipes. Surely you'll ultimately need to go richer on needles and main jet. You'll need to do an idle plug chop to see if you need larger pilots.

If it were me, I'd want to get plugs equal and verify what my exact setup is and then jet accordingly.

Normally with a newish bike people on the forum require the 3k mile service and then move from there. It's a baseline that must be done and timing is part of that.

Just, curious, what brand points and condensers do you have? See any logos? If I remember correctly you verified that your coils are good, but did you swap condensers to see if the issue moves to the other pair of cylinders?

But take my advice with a grain of salt. Since Cal and Fly both are thinking fuel delivery I'd would be focused on that right now.

[Calvin]

I have not verified the brand of the condensors yet.  I can look at them closely and see if I can find a brand, I have heard of some of the brands on here that are junk. 

I can measure the capacitance also of each one and compare it to that of the service manual, that could tell me something, or like you said just swap them.

I understand the focus on fuel, thats where I originally started, before I messed with any clip settings, I thought I should get all 4 cylinders firing consistently at idle first, which is why I am hesitant to check out the clip settings now.  I am not really trying to re-jet them, that was just a last second question in case anybody else thought that would be an issue with stock idle jets.  As far as idle jets being clogged I have cleaned them and even swapped jets from each carb, so I think it is safe to say that the idle jet itsself is not culprit, but that doesn't rule out the entire carb setup.

It looks like the only things I need to perform to fully complete the 3k mile maintenance would be:

Check/adjust ignition timing
Adjust valve clearance
Contact breaker point gap

Everything else has been done, except suspension related and steering head bearing inspection.


I can verify these three things in the next day or two. 

Fly, your suggestion for the tape sounds like a great idea.  I will try that shortly, along with checking/swapping condensers first.


Just to re confirm, the firing of #2 seems either intermittent, or it is much less powerful than cylinders #1 and #4.  At a smooth idle around 1200 rpm, I can pull plug wires 1 at a time and the results are:

#1: Engine stalls instantly
#2: Engine doesn't change or sometimes has a very slight idle drop
#3: Slight idle drop, engine still runs well
#4: Engine stall instantly

It could be firing, but much less powerful or effective than the rest

[flybox1]

Adjust valve clearance
Contact breaker point gap
Check/adjust ignition timing

Shame on us if we assumed it was done already 
Shame on you for not doing it if someone mentioned it in this thread 

GO DO THIS NOW!!!!  Make NO other changes.  Dont swap condensers...Dont tape your pods.

[flybox1]

Busted    Cal mentioned it in his first post.

Timing was ''just done" by the honda shop before I got it according to the PO.  I believe him, and I have only looked at the points to verify how the points looked because he said the points and condensers were just replace and timed by the honda shop, the points did look very new.  I believe the timing is good, I can check that last.  Right now, I want to get #2 firing.

You cant take anything the PO said as the truth 
So....Lets first start with what brand the points are.  TEC?   ND?  or Daiichi (3 leaf logo)?

[Scott S]

 I once had a coil that tested good in the garage and would intermittently cut out at speed/under load. I tested and checked everything you could think of and pulled the carbs 4 or 5 times. I finally took it to a shop and they just happened to have their gauges on the coil when it crapped out.

 I hate to tell you to throw dollar bills at it, but since it's relegated to 2/3, why not try a new coil?

[DaveBarbier]

Contact breaker point gap
Check/adjust ignition timing
Adjust valve clearance

Breaker point gap before timing.

[seanbarney41]

I have not verified the brand of the condensors yet.  I can look at them closely and see if I can find a brand, I have heard of some of the brands on here that are junk. 

I can measure the capacitance also of each one and compare it to that of the service manual, that could tell me something, or like you said just swap them.

I understand the focus on fuel, thats where I originally started, before I messed with any clip settings, I thought I should get all 4 cylinders firing consistently at idle first, which is why I am hesitant to check out the clip settings now.  I am not really trying to re-jet them, that was just a last second question in case anybody else thought that would be an issue with stock idle jets.  As far as idle jets being clogged I have cleaned them and even swapped jets from each carb, so I think it is safe to say that the idle jet itsself is not culprit, but that doesn't rule out the entire carb setup.

It looks like the only things I need to perform to fully complete the 3k mile maintenance would be:

Check/adjust ignition timing
Adjust valve clearance
Contact breaker point gap

Everything else has been done, except suspension related and steering head bearing inspection.


I can verify these three things in the next day or two. 

Fly, your suggestion for the tape sounds like a great idea.  I will try that shortly, along with checking/swapping condensers first.


Just to re confirm, the firing of #2 seems either intermittent, or it is much less powerful than cylinders #1 and #4.  At a smooth idle around 1200 rpm, I can pull plug wires 1 at a time and the results are:

#1: Engine stalls instantly
#2: Engine doesn't change or sometimes has a very slight idle drop
#3: Slight idle drop, engine still runs well
#4: Engine stall instantly

It could be firing, but much less powerful or effective than the rest

sounds to me like 2 and 3 are not running at idle at all...how about a quick cell phone video.  My best guess at this point, would be  bad condensor on 2 and 3.

[Calvin]

Updates to come tomorrow. Will check all of these remaining items for a 3k maintenance. Did not check these because I checked the points when I night the and it looked great and read the receipt from the honda shop.

I will post a video of the results pulling the plug caps at idle shortly.

Issue is always with cylinders 2 and 3.

I also plan to go to a dyna s with their 5 ohms coils shortly so the bad coil discussion may be answered.

[Calvin]

Here is a video I took yesterday.  Pretty self explainatory, you can see the points and condensers.  Then when I pull plugs to 1 and 4 you can see the bike dies immediately.  Pulling 2 or 3 really doesn't make much difference.  It is almost like those cylinders have much less power in the combustion than 1/4.  I do hear a slight idle drop when pulling 2 or 3, it may not be that audible in the video.  But a much different result when pulling plugs 1 and 4. 

Sorry I did not fully perform the 3k maintenance before posting, did not know it would be this involved of an issue.  I was just looking for some quick advice.  I can do them tomorrow, but I would not thing a valve adjustment would have anything to do with this since cylinder 3 had pretty good compression and 2 was slightly lower, but should still fire. 

Ignition timing is obviously important and I will go pick up a test light tomorrow and see how good of a job the honda shop did.  I will check the point gap also, I will have to do some reading in the manual on here.

[scottly]

No I have not checked the timing yet.

ALWAYS SET THE TIMING BEFORE SYNCING THE CARBS.

[Calvin]

So you didn't watch the video? 

Ok, ill verify timing tomorrow.

[scottly]

Timing can have a drastic effect on idle settings, like if the 2-3 points are retarded compared to the 1-4 points. Idle settings, on the other hand, don't have any effect on timing, so you always set the timing first.

[Calvin]

Timing can have a drastic effect on idle settings, like if the 2-3 points are retarded compared to the 1-4 points. Idle settings, on the other hand, don't have any effect on timing, so you always set the timing first.

Will do!  It's late and I've had one too many pabst blue ribbons tonight so this will be for tomorrow. Hopefully the 550 manual on here has good content on the timing process.  I think the one I have is a little ghetto and it's for a 500.

[seanbarney41]

Watched your video...I think the condensors are ok after all, and 2 and 3 are definitely firing and I think you are right about 2 and 3 being weaker than 1 and 4 for some reason.  Next step is do the 3k tuneup stuff in the correct order.  Whats with all that tape on the wires and caps?  Have you tested the resistance of your caps disconnected from the wires yet?

[Calvin]

Tape was on there when I bought the bike from the previous owner. Not sure why, maybe help protect from the heat? Really not sure.

I will take them off and check the plug cap resistance.

[Calvin]

So, I took the #4 plug cap off to check it out.  It is a Nichiwa VD05F resistor cap.  I looked it up and it looks like this one comes with 5K ohm resistance.  But I found this interesting because this thread:
http://forums.sohc4.net/index.php?topic=67096.0

Says that pre 76' bikes are 5k resistors and post 76' are 10k.  Not sure if my bike should actually have the 10k ones, but either way, I could not get a good reading and I have no idea why!

Basically, took the plug caps off, measured from the screw tip one the side that goes into the wire and on the other side making good contact where the cap seats on the plug.  I get like 20 M Ohms then it raises to OL.  Not sure if my meter doesn't have enough juice to measure it or what.  This is a Fluke 1577 insulation meter, its a very good meter, I don't think that would be an issue. 


 

[flybox1]

VD05F is the correct(5kohm) cap for 1 & 4, but if they are over 8Kohms, they are going bad. 
Best to replace ALL of them w (5kohm) NGKs and known good D7EA plugs.

[Lostboy Steve]

So, I took the #4 plug cap off to check it out.  It is a Nichiwa VD05F resistor cap.  I looked it up and it looks like this one comes with 5K ohm resistance.  But I found this interesting because this thread:
http://forums.sohc4.net/index.php?topic=67096.0

Says that pre 76' bikes are 5k resistors and post 76' are 10k.  Not sure if my bike should actually have the 10k ones, but either way, I could not get a good reading and I have no idea why!

Basically, took the plug caps off, measured from the screw tip one the side that goes into the wire and on the other side making good contact where the cap seats on the plug.  I get like 20 M Ohms then it raises to OL.  Not sure if my meter doesn't have enough juice to measure it or what.  This is a Fluke 1577 insulation meter, its a very good meter, I don't think that would be an issue.

Yes, 10k ohms are unobtainium. Check the hondaman chronicles for more info on this. I run 5k ohms with 5k dyna coils. Works lovely.

[Calvin]

I checked the resistance of the plug caps again.  #1 was so corroded I couldn't get a reading, but here they are:

#1: N/A
#2: 4.3 K Ohm
#3: 4.5 K Ohm
#4: 5.7 K Ohm

2 and 3 are the problem cylinders right now.  Debating on replacing these plug caps for 25 bucks or just forking over the money for the Dyna Coils and then Dyna wires with caps. 

I will still finish the 3k maintenance after work today.

[flybox1]

2.3.4 would be fine to reuse.

[Calvin]

So I did the static timing today.  At first it seemed that 1/4 were a little advanced when I checked it, then 2/3 were a little bit closer, but not as advanced as 1/4.  First thing, I set the contact breaker gaps to be .012", when I got into it at first, they were a bit less, probably like .008" maximum.  It seemed like the points were not perfectly parallel when they made contact so one side of the point would fit a .008" feeler gauge in (the wider side) and the other side was too narrow for even like a .005".  I got them each to .012" then started adjusting the timing plate.  I had to change it quite a bit and feel that I got them pretty dang close now.

I attached a link to about a 1:30 minute video showing when the test light comes on.  I would appreciate it if somebody could verify it.  I know it is not absolutely perfect, but its many degrees better than before.

Not sure why the quality is so much worse when I uploaded it to youtube.

At first, the battery was pretty dead and it didnt fire up after cranking 3-4 seconds, then the starter was out of juice.  I charged it for 30 minutes and it fired right up.  Now that the points gap is a little larger, I notice some sparking/arcing of the points at idle.  It is not every time they make contact, but more than before.  I read on here that its not always an issue, unless its causing pitting and corrosion.

Tomorrow I will finish up the 3k maintenance by checking the valve clearance.  Funny, I bought this specific bike because the PO had said a lot of this stuff was done, I'm sure it was.  But after cleaning the carbs the first time, I basically had to redo it all... ha.  Oh well, I learned a lot.