Topic: CB 550 Headache

[Juggernaut90]

Any advice would be appreciated.

My CB 550 has issues turning on and will not hold idle. When the bike turns over after 30 good kicks and a few bad words it seems to run strong (as long as I hold the throttle open). It doesn't run choppy as I would expect it to if the compression was the issue. When I had the compression checked I was told it was still in the "good enough" range. I believe lowest cylinder was 118 (?)

I have taken the bike to 3 different mechanics who advised me it was a Carb related issue. Still no luck. I have tried the stock jet kit sigma six jet kits, and now I am back to stock.

Recently, a new mechanic advised me to replace the coils which I did and it still has the same issues. Ordered the used coils on eBay and installed myself. I thought it was the coils because of the backfire in the exhaust and the spark plugs get fried in after a few starts.
 
So! I am not sure what to do at this point. I had the carbs done this week, I installed the new coils, new battery, throttle cables installed, and I still have the same issues. Could it be that the carbs just need to be adjusted? Sorry if this is a lengthy post I am hoping someone will convince me to not sell Its been three years and I've only enjoyed the bike for a +- 20 miles. 

[evinrude7]

i'm sure someone else will pipe up here with years more experience than i have.  start with the 3000 mile service.  you can get the manual through the forum if you don't have it.  if done correctly it takes care of most issues. 

[RAFster122s]

If you have repeatedly been told it is a carb issue, then why wait three years todo something about cleaning them.  Compression numbers often come up after running a while when everything is set correctly and the bike has had some miles put on it.

The bikes in stock form run best when paired with the stock factory airboxand filter setup.  Pods can be made to work but require more expertise than you currently possess and not to have it running with the stock airbox first you throw too many variables into the equation to accurately diagnose remotely easily.

The carbs do not run well on aftermarket brass and are best to obtain or use stock Keihin carb brass parts for all your jets.  You will need to find out what brass and jet sizes are in your three jets for each carb if your mechanic cannot tell you.  The person cleaning your carbs did not clean them if they did not remove the jets first.

The brass must be clean and deposit free.  Often it may appear they are clean but they really have a film deposite on them that changes their openings a bit leading to issues.

The o ring between the intake manifold and head is often bad, worth checking and replacing.  Carb boots that are hard can introduce leaks as well. Do not buy aftermarket boots, you will be buying them again either very soon or in a couple years if you get that much use out of them.  Honda OEM from a discount dealer like South Sound Honda of Olympia Washington gives very good prices across the board on parts.
Air leaks can give lean running and cause backfires.


You need to provide some more info, what year bike, which carbs?  What jets? What gaskets have been replaced?  Were the carbs bench sync'd when cleaned and reasssembled.  What did they do to clean them?
stock motor and air filtration system?
how many miles?
Factory workshop manual will tell you where to find the carb numbers on the flanges and show you other things.  Read the manual section on the 3k mile tuneup and replace the plugs and set timing and valves per factory manual for 3k service procedures.
carb section tells you how to bench sync and vac sync will be needed after bike is running again. 
What kind of condition and age on points and brand for them and condensors?

David

[Deltarider]

Recently, a new mechanic advised me to replace the coils which I did and it still has the same issues.

Classic.

the spark plugs get fried

What do you mean by that?
Here are five easy checks I'd start with.
1. See if there's any (intermittent) arcing between the HTleads or plugcaps and the engine (= GND). Best seen in the dark.
2. Check the condensers. At the breakerpoints a tiny bit of sparking is normal, excessive sparking is not good. See:

In the vid left condensor (1+4) is bad, right condensor (2+3) is good. Whilst you're there, also check the spade connectors at the breakerpoints do not intermittently contact the baseplate (especially 2+3 can touch easily!).
3. What do the plugs look like and whilst you're there, check the resistance of the plugcaps. They should be around 5000-7500Ω (some say 10kΩ). All four should read more or less the same resistance. Screw the caps on to the leads again firmly. BTW, replacing sparkplugs can work miracles.
4. Does fuel reach the carbs unhindered? Check by opening the drain screws. No 'extra' inline fuel filters I hope?
5. Slow jets are often the culprit, the more if bike has sat for a long period of time. But then we first need to know what model CB550 you have: one of those with the oldstyle Keihin carbs or the CB550K3/K4 that had the newstyle PD carbs. We'd also like to know if you have a timing light to check the advancer.

[TwoTired]

Show us pictures of the spark plug tips.

Who has done the routine 3000 miles tune up schedule?

Bad condensers can hinder spark. Have you tried new ones?

Did the person who did the compression test use an instrument intended for small engines?

Do you turn off the headlight when trying to start?

Have you measured the voltage on the black wire during start attempts?

Details about your bike could be helpfull?

Outline your start up routine in steps?

Cheers,

[Juggernaut90]

The brass must be clean and deposit free.  Often it may appear they are clean but they really have a film deposite on them that changes their openings a bit leading to issues.

The o ring between the intake manifold and head is often bad, worth checking and replacing.  Carb boots that are hard can introduce leaks as well. Do not buy aftermarket boots, you will be buying them again either very soon or in a couple years if you get that much use out of them.  Honda OEM from a discount dealer like South Sound Honda of Olympia Washington gives very good prices across the board on parts.
Air leaks can give lean running and cause backfires.

You need to provide some more info, what year bike, which carbs?  What jets? What gaskets have been replaced?  Were the carbs bench sync'd when cleaned and reasssembled.  What did they do to clean them?
stock motor and air filtration system?
how many miles?
Factory workshop manual will tell you where to find the carb numbers on the flanges and show you other things.  Read the manual section on the 3k mile tuneup and replace the plugs and set timing and valves per factory manual for 3k service procedures.
carb section tells you how to bench sync and vac sync will be needed after bike is running again. 
What kind of condition and age on points and brand for them and condensors?

David

Thank you for replying! It took me a while to get to the bike because there are not any shops that are local to me. I have to take the bike pretty far to get it serviced. Don't have a truck/trailer. Now I have triple A so I am using that for now.

It is a '74 CB 550. It has pods. I will look into getting an airbox for it. I am not sure on the mileage bc I just found out that the gauge on it belongs to a 750. It reads ~30,000 but who knows if thats accurate   

It has the stock Keihin Carbs. The factory jet kit was installed with it this last week when I had the carbs done again. I know some gasket was replaced this last time I took it in, but I am not 100% which one. I believe they had to completely re do them bc the mechanic did not like the other kit installed and believed bringing it as close to factory would be best.

I will also check out the O-Ring between the carbs and Manifold. I didn't know about that 

Points were also adjusted/cleaned this last mechanic visit bc mechanic also had issues turning the bike over. Not too sure about the condition or age. I will upload pictures if that helps. He put in new sparks which are already looking fried.

I will also look into the bench/vac sync in the manual and the 3000 mile service! Thanks!!!!

[Juggernaut90]

Recently, a new mechanic advised me to replace the coils which I did and it still has the same issues.

Classic.

the spark plugs get fried

What do you mean by that?
Here are five easy checks I'd start with.
1. See if there's any (intermittent) arcing between the HTleads or plugcaps and the engine (= GND). Best seen in the dark.
Looking up how to do this now.
2. Check the condensers. At the breakerpoints a tiny bit of sparking is normal, excessive sparking is not good. See:

In the vid left condensor (1+4) is bad, right condensor (2+3) is good. Whilst you're there, also check the spade connectors at the breakerpoints do not intermittently contact the baseplate (especially 2+3 can touch easily!).

3. What do the plugs look like and whilst you're there, check the resistance of the plugcaps. They should be around 5000-7500Ω (some say 10kΩ). All four should read more or less the same resistance. Screw the caps on to the leads again firmly. BTW, replacing sparkplugs can work miracles.
4. Does fuel reach the carbs unhindered? Check by opening the drain screws. No 'extra' inline fuel filters I hope?
5. Slow jets are often the culprit, the more if bike has sat for a long period of time. But then we first need to know what model CB550 you have: one of those with the oldstyle Keihin carbs or the CB550K3/K4 that had the newstyle PD carbs. We'd also like to know if you have a timing light to check the advancer.

Thanks for the Reply! Will check and get back asap! Thanks for the links.
5.Its a 74' CB 550.
4.It has one fuel filter per line leading into the carbs.
3.I just replaced the coils and it came with old original plug caps. The one that goes to Cylinder 4 fits a little funky. I was going to replace the lines/plugs as soon as I figured out how. Didn't want to mess with them too much bc I couldn't tell by looking at the old coils if I was going to ruin them by trying to take them off.
2. Going to check this asap and get back. Thanks for the video!
1.  Looking up how to do this now! Will update.

[Deltarider]

Now that I know you have these inline filters, I'd first make sure fuel flow is not hindered in any way. Inline fuel filters can do that and often do so intermittently which makes it even harder to diagnose. Don't ask me how I know. When the petcock filter is still there and in good order, there's NO need for any inline filter whatsoever. These filters often hinder a constant flow and so do fuel lines that are not standard and can kink. With the appropiate length and diameter of the fuel lines (for your model that's: 18 and 30 cm resp., ⌀ 5,5 mm), it is practically impossible to route them wrongly > guaranteed no kinking.
 

[HondaMan]

Umm...did you replace the O-rings in the castings that hold the carbs to the head? They leak, now, so it will be nigh-on impossible to adjust mixtures with them like that. Also check the clamps on the rubber hoses, make sure they are snug.

[Juggernaut90]

Umm...did you replace the O-rings in the castings that hold the carbs to the head? They leak, now, so it will be nigh-on impossible to adjust mixtures with them like that. Also check the clamps on the rubber hoses, make sure they are snug.

I didn't personally. Going to have to call the mechanic to verify. He took the carbs off and re-assembled them for me. Thanks for the tip!

[Juggernaut90]

Now that I know you have these inline filters, I'd first make sure fuel flow is not hindered in any way. Inline fuel filters can do that and often do so intermittently which makes it even harder to diagnose. Don't ask me how I know. When the petcock filter is still there and in good order, there's NO need for any inline filter whatsoever. These filters often hinder a constant flow and so do fuel lines that are not standard and can kink. With the appropiate length and diameter of the fuel lines (for your model that's: 18 and 30 cm resp., ⌀ 5,5 mm), it is practically impossible to route them wrongly > guaranteed no kinking.
 

I just realized one of the hoses is not allowing gas to flow through freely. Tomorrow I am installing new fuel lines and I am going to check out the petcock.  Also, am I supposed to be able to see any spark while the cover is removed and I am trying to turn the bike on? No luck today getting the bike to turn over. My knee sure does hurt.

[Deltarider]

I wouldn't perform any further checks before you have restored a correct fuel flow. So allow your knee some rest.

[Juggernaut90]

I wouldn't perform any further checks before you have restored a correct fuel flow. So allow your knee some rest.

I removed the old lines with the filters. Opened the Petcock, and the flow seems to be fine. So I didn't disassemble it. I tried to turn the bike over and no luck s far. I think the battery was too weak. Going to give it another go later on when the battery has had more time on the charger.

Starting to wonder if the coils I bought on eBay are no good too. I noticed the one which runs to cylinder one is a little wide. Fits a little weird on the spark plug. Any recommendations on a replacement?

[TwoTired]

Do you have the stop-run-stop switch in the run position?

Just checking.

Cheers,

[Juggernaut90]

Do you have the stop-run-stop switch in the run position?

Just checking.

Cheers,

Lol yes. I did notice my switch is stop, run, stop. It sounds like it wants to start sometimes when I am kicking it over and the battery is full. Not sure why every 100x times it will. I think i will go to the condensors next. Maybe buy NEW coils as opposed to used. I should upload a video.

[Ace Blackwell]

A video of you kicking 100+ times could be a rather large file.  You might want to break it down into videos of 20 kicks each 8-)

[TwoTired]

So, just to reiterate.  You need an air fuel mixture somewhere in the wide neighborhood of 14.5 to 1, compression, and then spark timed correctly.
Engine has no choice but to fire off. 
If it doesn't run something is missing, and you need to find out what it is.

Have you laid the connected plug on the engine to see it sparking?  Both coils?

Have you checked the spark plug center electrode insulators for a covering of soot?  All Four?

Done a compression check?

Do the removed spark plugs smell like fuel?

Spark plugs are your window into combustion conditions.  Looking at the tips can tell you things, whether in running status or not running status.

Cheers,

[calj737]

...and, to be sure, you have the new coils wired to the correct plugs? The Blue wire from your ignition drives the coil to cylinders 1&4, the Yellow wire drive cylinders 2&3. You would not be the first person to inadvertently wire the coils 1/2, 3/4 and muck up the firing order.

[Bankerdanny]

The starter turns the bike over far faster than you can kick. You are better off using the starter for its intended purpose until you have everything sorted, at which point the kicker should work fine.

If the battery is so weak that it won't turn the engine over then it is likely too weak to properly start it with the kicker.

[Juggernaut90]

The starter turns the bike over far faster than you can kick. You are better off using the starter for its intended purpose until you have everything sorted, at which point the kicker should work fine.

If the battery is so weak that it won't turn the engine over then it is likely too weak to properly start it with the kicker.

Thanks! i ended up thinking something was wrong with the starter. But, I noticed the new battery was not charging correctly. It ended up being defective and now I have a Truegel battery which seems to be working a lot better. So now, my bike sounds like it wants to start, and holds charge long enough for me to get it going eventually. New issue is that it dies even with the throttle wide open. I managed to get a video of me trying to start it but not one with it on. Going to upload and post a link.

...and, to be sure, you have the new coils wired to the correct plugs? The Blue wire from your ignition drives the coil to cylinders 1&4, the Yellow wire drive cylinders 2&3. You would not be the first person to inadvertently wire the coils 1/2, 3/4 and muck up the firing order.

I replaced with used coils on eBay. I am now considering investing in Dyna coils. Maybe even getting the whole ignition kit + wires. Just so I can eliminate that being one possible reason why its not firing up right away. When i remove the sparks I smell gasoline. So I think its more of an electrical issue. Someone mentioned purchasing new condensors. I tried to see the things sparking while I had it on for the time I did but I couldnt see anything.

So, just to reiterate.  You need an air fuel mixture somewhere in the wide neighborhood of 14.5 to 1, compression, and then spark timed correctly.
Engine has no choice but to fire off. 
If it doesn't run something is missing, and you need to find out what it is.

Have you laid the connected plug on the engine to see it sparking?  Both coils?

I checked the coils they do give spark. Not sure if they weaken over time. Was considering trying a dyna set up.

Have you checked the spark plug center electrode insulators for a covering of soot?  All Four?

Is that the spark caps? Or the spark plug tip itself? The plugs are really old and one of them doesnt fit so well. I believe it belongs to cyl 4. It does spark but I am not sure if the spacing is an issue. Plugs get a little burnt looking when I remove them.

Done a compression check?
Rented a tool from Autozone. It was an OEM compression gauge. I could not get it to fit inside the block. So i think i may have to purchase one from amazon. If you have any reccomendations please link and thank you so much!

Do the removed spark plugs smell like fuel?
Yes. Will Shoot a new video showing everything!

Spark plugs are your window into combustion conditions.  Looking at the tips can tell you things, whether in running status or not running status.

Cheers,

I answered within the quote 

[calj737]

Have you laid the connected plug on the engine to see it sparking?  Both coils?

I checked the coils they do give spark. Not sure if they weaken over time. Was considering trying a dyna set up.

Have you checked the spark plug center electrode insulators for a covering of soot?  All Four?

Is that the spark caps? Or the spark plug tip itself? The plugs are really old and one of them doesnt fit so well. I believe it belongs to cyl 4. It does spark but I am not sure if the spacing is an issue. Plugs get a little burnt looking when I remove them.

Stop buying and trying, and replace your spark plugs with 4 new, proper spec plugs! Fouled plugs, improperly gapped plugs, or incorrect plugs all contribute to your issues.

TT is asking you to evaluate the tip of the plug itself where the ceramic electrode and strap are. The plug caps need a measurement of their resistance value.

[TwoTired]

Coils do not normally weaken over time.  Physical damage is another issue. As well as spark lead damage.  Have you inspected for damage?

Spark plug tips can tell you a lot about engine run issues.  If you can "read" them, they can tell you what needs to be changed.  Further, if one plug shows different deposits than others, you can focus on 1/4 of the engine, rather than all of it.
It a nice diagnostic tool that focuses your efforts on the specific problem.

My philosophy is, that if you have enough data on an issue, the data will point to what needs to be fixed or changed.

Cheers,