Topic: 550 misses after a short ride...?

[scadaman29325]

After a good run of 5 minutes, my '77 550 starts missing when thorttle is applied and will die if I don't keep it juiced.

Runs GREAT for the first 5 minutes though, no choke needed... Idles and revs fine before riding... I can get the front wheel off the ground during the first 5 minutes... REALLY scoots down the street...

Then it'll start missing when accelerating, and when stopping if I don't keep the gas into it, it will die, but cranks and starts right back but still with the missing when accelerating...

I put it on the rack for this problem. Installed a good airbox and rubbers, cleaned the carbs and synched them (no other adjustments), new plugs. DID NOT do timing/points...

Anybody got a lead? Maybe points and condensor next?

I'm sort of new to this kind of troubleshooting.

Thanks in advance for the help, Phil

[gerhed]

Sounds lean.
Rule of thumb:
If it starts good, idles good, revs good ,but
chokes under load--it's lean.

[rbmgf7]

yeah, maybe lean. my KZ would run great for about half an hour, overheat from running lean, and then basically shut down. I'd have to let it cool for a few minutes to ride again.

[TwoTired]

Do you have the stock exhaust and air filter on it? (Important information)

A restricted filter, clogged with dirt, will allow the engine to run well cold, but be too rich when warmed up.  Sputtering, like the choke was left on.

Actual choke application will make it die, possibly.

You should certainly need choke on cold start up with this bike, as they typically run leaner than earlier models.

Does it run better without the air filter in place (temporary diagnostic action)?

Look for black deposits on the spark plug center electrodes to confirm over-rich condition.  (What spark plug numbers do you have?)

But, realistically, complaining about performance issues without doing a complete tuneup is, IMO, a bit premature.

Cheers,

[bozo4onion]

Mine (75 550F) did this and it drove me crazy. Turned out to be a condenser. Ran great till it got hot. Seemed to crap out after high rev aggressive driving too. Good luck.

[scadaman29325]

Thanks for the help all.

I'm very new to this and been trying different stuff, but that is the reason I'm here

Been doing some reading, I'm now thinking it's too rich, and am trying to figure out what caused it and how to fix it.

Here's some info and some test results...

The exhaust has been modified (cut and gutted, sounds like a 2 cycle) (it's a 550F and has the 4 into 1 Exhaust).
This may be what caused the problem (cut and gut), but it's my wife's bike and she really likes the sound, so I won't be messing with the exhaust.

It will die when choke is applied.

It is a stock filter and did not look to dirty.
It runs good (not great) without the air filter. Went on a 30 minute ride last night, got it up to 80 pretty quick.
When I got the bike, some of the airbox parts were missing and some rubbers were tore and not connected.
In hindsight I remember that it had ran ok until I reconnected the rubbers. (Replaced all 4 rubbers later)
I think I need to check the jets but I don't want to take those carbs off again (what a PAIN).

The plugs are D7EA and VERY 'sooty' (fouled?).
I tried D8's before the rubber swapout, but that didn't help, they were very sooty also after just a few minutes.
May I can try that again.

I'm thinking a K&N air filter may help a little (more air than stock), but something else will be needed (re-jetting?, regardless of my pain threshold).

Any other ideas out there? (Before I dig into the carbs)(I'm crying already).

Again, THANKS for the help, Phil

[hapsh]

Everything you said points to an over rich condition.  Have you checked your air/mix screws, float level?  I think the 77s have the air screw, so turning it out leans the mixture.  If your float level is too high it will richen your whole throttle range.  I do think however you need to make sure you check your timing and valve clearance as well.

[scadaman29325]

Everything you said points to an over rich condition.  Have you checked your air/mix screws, float level?  I think the 77s have the air screw, so turning it out leans the mixture.  If your float level is too high it will richen your whole throttle range.  I do think however you need to make sure you check your timing and valve clearance as well.

Yeah, I'm fixin' to learn a lot about fixin' this machine. I was hoping it would be easy (for some folks this may be easy).

Thanks, Phil

[Porscheguy912]

I have a 550 with pods, open pipe 4-1 exhaust and i rejetted the bike to 115 main jets.

It sounds to me whats happening is you have a rich condition; You have an open exhaust and stock airbox. Basically your exhaust is "flying out of the pipe" too fast and not applying the proper back pressure to keep your mixture proper with the stock (more restrictive filter).

Spend $45 bucks on pods and jets cost like 8-15 bucks total for four mains and shipping.
I rebuilt and re jetted mine in one night and a 6-pack and i was riding it by morning.
The biggest pain is like you said weaseling the carbs out and dealing with the accelerator cable.

Or, get a stock exhaust back on the bike.

Also, dont over oil your pods!! i made that mistake and my heart sank for a hour till i figured out what i had done!

I would Def get new points and condensers too. Sometimes the condensers fail when they get hot, so that could be part of the problem too.

I changed my points and condensers last, after the carb re jet. When i did, i noticed that my timing was off really bad too. and of course i had adjusted the carbs to the old points and condensers too. So i had to re adjust everything. It was weird, the bike wold run great, idle great, but it would bog and misfire at high RPMs in 1st gear. I checked the timing and like i said it was way off. I changed it and it runs great.

i hope this helps!

jeremy

[TwoTired]

It sounds to me whats happening is you have a rich condition; You have an open exhaust and stock airbox. Basically your exhaust is "flying out of the pipe" too fast and not applying the proper back pressure to keep your mixture proper with the stock (more restrictive filter).

Well, this is simply junk science.   While I agree there is likely an over rich condition.  And open exhaust will require more fuel for the high speed mix. A "choked" filter would do just that.  Of course, anything but high throttle settings would be pretty piggish.

The exhaust has been modified (cut and gutted, sounds like a 2 cycle) (it's a 550F and has the 4 into 1 Exhaust).
This may be what caused the problem (cut and gut), but it's my wife's bike and she really likes the sound, so I won't be messing with the exhaust.

It will die when choke is applied.

Tends to indicate your mixture is too rich, unless you are applying choke fully.  This blocks the air intake and makes the engine subject to "blackouts", like you would if you closed your nose and mouth.

It is a stock filter and did not look to dirty.

You can't tell by looking at it.  How old is it?  Humidity makes the fibers more dense with time and thus it gets restrictive, like having the choke on all the time.  Replace the paper ones every 6 months.  Most don't do this, due to the expense.  Or...
Get yourself a Uni 4055 drop in replacement foam air filter.  These are freer flowing, cleanable and re-usable.  I've seen them on line for like $25.

If you want carb re-jetting and tuning headaches then get PODs.

It runs good (not great) without the air filter. Went on a 30 minute ride last night, got it up to 80 pretty quick.
When I got the bike, some of the airbox parts were missing and some rubbers were tore and not connected.
In hindsight I remember that it had ran ok until I reconnected the rubbers. (Replaced all 4 rubbers later)
I think I need to check the jets but I don't want to take those carbs off again (what a PAIN).

Why isn't this telling you your filter is a problem?

The plugs are D7EA and VERY 'sooty' (fouled?).
I tried D8's before the rubber swapout, but that didn't help, they were very sooty also after just a few minutes.
May I can try that again.

Soot is unburned fuel.  Like maybe to much fuel is getting to the engine and not enough air.  D7s work well and make the engine nice to run while it's warming up.  Use the D8s when driving through the hot desert flat out.

I'm thinking a K&N air filter may help a little (more air than stock), but something else will be needed (re-jetting?, regardless of my pain threshold).

K&N don't make a drop in replacement for the 550.  They make pods, though.   Then you WILL need do the re-jetting exercise.

After you get the new filter, change your spark plugs too.  All that soot makes them fire badly and the engine will still be "(not great)"

The open exhaust may still require a main jet change for WOT operation.  The Fs with the 069a carbs had #98 mains, the smallest of the early carb 550's.  Other's, with the 4 into 4 used #100's.  It's a bit tricky, but you can change the mains with carbs on the bike.  Plan on new orings for the jets, though.

Cheers,

[edbikerii]

This advice is inadequate, as the 77-78 carbs differ significantly from those on the prior years.  I rejetted my 77 and found that 115 was way too rich with EMGO pods and MAC 4-1 exhaust.  I ended up with 105s.  Do a search and you'll find the entire thread.

I have a 550 with pods, open pipe 4-1 exhaust and i rejetted the bike to 115 main jets.

[TwoTired]

Ed,
The 77 550F model uses the same carbs as prior years of the F, not the PD type found on the K models.

I stand by my advise for the original poster's bike.

Cheers,

[Porscheguy912]

Well, this is simply junk science.   While I agree there is likely an over rich condition.  And open exhaust will require more fuel for the high speed mix. A "choked" filter would do just that.  Of course, anything but high throttle settings would be pretty piggish.

TwoTried, Whats the deal?
Last i checked this was an open forum dedicated to helping people not bashing peoples opinions. Just because you spend your entire day waiting for someone to post so you can throw in your two cents worth of regurgitated knowledge, doesn't give you the right to call someones opinion "Junk science", Mr. 5230 posts.

I have seen many of your posts on here, and your experience has helped me out in the past.
Why the gruntled attitude today?

Besides If you read what you said about my post you are saying the same thing in a different way. Point=

And open exhaust will require more fuel for the high speed mix.

Just like i said, but i described it via experience not blind wisdom. I had the same issue and i re-jetted and moved to a less restrictive air filter. Problem solved.

This guy has a completely open exhaust, stock air box and no carburetor mods and your trying to say that his "dirty air filter" is the culprit, after he said it looked fine and he ran it with out and still had issues?

To quote scadamann29325,

It runs good (not great) without the air filter. Went on a 30 minute ride last night, got it up to 80 pretty quick.

So, he already tried running it with the air filter off and it sound like it ran better, but not "Great"

You say check the filter, I agree. But it sounds like he already has. (see quotation)

But I would say that a good rule of thumb is (and i think most people would agree that have ever worked on any engine with a carburetor)
"If you open up one end of an engine up, you will have mixture issues until you open up the other end or re-jet." Ergo, Get the version of an air filter/carb that is best suited to your exhaust situation. (in his case open)

And to edbikerii.

I re-jetted my 77 and found that 115 was way too rich with EMGO pods and MAC 4-1 exhaust.  I ended up with 105s.

I agree with you. 115's are too much for a bike with a Mac 4-1 with pods. Most macs that i have seen have baffles in them. I would say that if you took your baffles out to have no restriction at all, it may run better with 115's. Or do you already run with no baffles?

But on the other hand My bike is a 1975 and yours is a 1977 and if you are right, and they do have different carb setups entirely, perhaps they need smaller mains because of some other modification that makes them different between years.

Man, can't we all just get along and have a mutual exchange of knowledge and experience like scholars and leave the testosterone out of it?

Sheesh. No posts on here since last season and this is the welcome i get?
I should have kept quiet.

[TwoTired]

Well, this is simply junk science.   While I agree there is likely an over rich condition.  And open exhaust will require more fuel for the high speed mix. A "choked" filter would do just that.  Of course, anything but high throttle settings would be pretty piggish.

TwoTried, Whats the deal?
Last i checked this was an open forum dedicated to helping people not bashing peoples opinions. Just because you spend your entire day waiting for someone to post so you can throw in your two cents worth of regurgitated knowledge, doesn't give you the right to call someones opinion "Junk science", Mr. 5230 posts.

I have seen many of your posts on here, and your experience has helped me out in the past.
Why the gruntled attitude today?

Jeremy, 
 I'm not [sic] "gruntled" at you.  My response is because of what you posted.
"Quote from: Porscheguy912 on Today at 03:40:07 pm
It sounds to me whats happening is you have a rich condition; You have an open exhaust and stock airbox. Basically your exhaust is "flying out of the pipe" too fast and not applying the proper back pressure to keep your mixture proper with the stock (more restrictive filter)."

Does this not sound that you are trying explain his over rich condition by an open pipe causing the air filter to become more restrictive?  These two items are isolated by an intake and exhaust valve, for pity's sake.  I have to call that junk science as that theory has no basis in reality.  It's NOT going to help Phil's understanding of what and why to fix his bike.  Why is it you think copying what you did to your bike, thereby cloning yours,is going to help him get his bike working in the shortest possible time?

Further, I did not attack you, but your theory and/or position on the matter, which I still feel is wrong and misleading to an admitted "newbie".   You took it personally and then made a personal attack.  Are your opinions and understandings on a single topic not separate from you as a person?

This is not the open forum, but the tech forum, BTW.

Besides If you read what you said about my post you are saying the same thing in a different way. Point=

And open exhaust will require more fuel for the high speed mix.

Just like i said, but i described it via experience not blind wisdom. I had the same issue and i re-jetted and moved to a less restrictive air filter. Problem solved.

This guy has a completely open exhaust, stock air box and no carburetor mods and your trying to say that his "dirty air filter" is the culprit, after he said it looked fine and he ran it with out and still had issues?

To quote scadamann29325,

It runs good (not great) without the air filter. Went on a 30 minute ride last night, got it up to 80 pretty quick.

So, he already tried running it with the air filter off and it sound like it ran better, but not "Great"

You say check the filter, I agree. But it sounds like he already has. (see quotation)

He ran it without a filter and dirty plugs.  There was improvement, which was the test, indicating he was on the right track.  I never claimed it to be a cure-all.  He professed to be a newbie, and I suspect he doesn't know about the fibers collapsing and a filter that "looks" clean still not flowing properly.  Besides, has he seen a real bona fide clean one?  Did he test it for actual air flow?  I suspect not.  Any bets his paper air filter is over six months old or even years?  And, if it ever got wet, it surely is more restrictive, now.

But I would say that a good rule of thumb is (and i think most people would agree that have ever worked on any engine with a carburetor)
"If you open up one end of an engine up, you will have mixture issues until you open up the other end or re-jet." Ergo, Get the version of an air filter/carb that is best suited to your exhaust situation. (in his case open)

Most people used to agree the earth was flat.  Didn't make it true. 
Engine breathing in the SOHC4 is dominated by the cam and displacement.  Just because you make your butt hole bigger doesn't mean you can eat twice as much or require you to have a bigger mouth.  Exhaust back pressure relief makes little mixture difference until you reach the max limits of the engine breathing.  This means high RPM.  Phil's stated issues are not at WOT or 9-10K operation where the exhaust back pressure comes into play for performance.  The stock muffler on the F model has higher backpressure than open.  But, this allows for a leaner correct mixture setting of the carbs.  The open exhaust would not change the fuel delivery mixture, if anything the open exhaust would leave the engine running LEAN not rich.  His running rich is NOT caused by open exhaust.

Man, can't we all just get along and have a mutual exchange of knowledge and experience like scholars and leave the testosterone out of it?

What testosterone?  The bunch that you're introducing?  Disagreeing with/challenging your "opinion" denigrates your manhood?  I don't know why you decided to take it personally.  I shouldn't be forced or coerced into agreeing with a technically flawed position, just to remain "pals".  You think "scholars" agree on everything?

Phil can believe anything he wants.  His bike. His time. His choice.  It's a pity there can't be a united front for his MC problems.  I can only try to guide him toward corrective measures that use the least of his time, given the data he has presented.  If he wants to put on pods and deal with the issues they introduce, that's his choice.

Sorry, if you're offended, Jeremy.  It was never "personal" by intent on my part.   Just trying to get the "requester" the best info.  Perhaps you are right, though, over 5000 posts is just too many.  Would you recommend I delete some, or just not post anymore?  (Though, i don't know why that has any relevance to the issue at hand.)

[hapsh]

...And, we're back...

Yeah, I'm fixin' to learn a lot about fixin' this machine. I was hoping it would be easy (for some folks this may be easy).

Thanks, Phil

Fixing problems like this should be enjoyable or at least challenging in a good way.  To make sure you don't get frustrated I would read through the Faq, download a copy of the shop manual, and familiarize yourself with the basics of what makes an engine run.  Once you understand what needs to happen to make the engine fire properly you can systematically go through all the steps to make sure all the primary functions are operating.  An engine needs Fuel, Air, Fire, and Compression, and If you go through the shop manual it will guide you through the proper order of diagnostic checks to make sure the engine is having these needs filled.  If you jump in and start fighting an issue without doing a basic checkup you will more than likely get frustrated.  Even on a great running bike that you buy used it is still a good idea to go through and do a checkup, just so you don't get stranded on the roadside.

[edbikerii]

Yes, of course Lloyd, I forgot about the 77F model having the earlier carbs.  In fact, I momentarily forgot about the F models altogether.  I freely admit that I have absolutely no experience with either the 550F models or the pre-77 550 carbs.

I was actually just replying to porscheguy912's jetting, which seems incredibly rich to me if he is referring to a 77 CB550K.  Of course, if he has an F or has carbs from an earlier bike installed, then I don't know a damned thing about it.

Cheers,

Ed

Ed,
The 77 550F model uses the same carbs as prior years of the F, not the PD type found on the K models.

I stand by my advise for the original poster's bike.

Cheers,

[mystic_1]

Just because you make your butt hole bigger doesn't mean you can eat twice as much or require you to have a bigger mouth.

I'm sorry, I have nothing constructive to add to the thread, but I just wanted to say that this cracked me up big time, adn enhanced my understanding of engines at the same time! 

[Porscheguy912]

TwoTired: Whatever man, your always gonna be right and so am I.

edbikerii: Yes, it does seem sometimes that my bike runs a bit rich but it hasn't presented any sort of problems. I get great performance and i still get around 50mpg even with a heavy wrist like mine. BTW i have a 75' 550F.

scadaman29325: Sorry dude. I didn't mean to hijack your thread. I simply thought that you may want a quick solution to your problem. I had the same problem and thats how i fixed it.

Jetting isnt that hard and pods are easy to install. In my opinion, i would rather do that, and gain a few ponies and solve the problem then bang my head against the garage wall and read mindless grease monkey opinions on the web. I was just trying to get you a solution the quickest way possible so you can develop carpal tunnel from operating the throttle, rather than the mouse.
I by no means wanted to you to "Clone my bike" and someone else suggested.

j-out.

[edbikerii]

edbikerii: Yes, it does seem sometimes that my bike runs a bit rich but it hasn't presented any sort of problems. I get great performance and i still get around 50mpg even with a heavy wrist like mine. BTW i have a 75' 550F.

50 MPG!!!  That's unbelievable for a CB550.  Are those imperial gallons or something?  I have the 77 "lean burn" carbs, and even in stock form, I'm pretty sure I only get around 35 mpg (US Gallons).  I do tend to go about 80 on the highway, and then putt around in the city a bit.  My fuel economy is about the same after pods, MAC and jetting as it was when it was 100% stock.

The fact that you are talking about a 75 550F makes your jetting requirements completely different than my 77 550K.

Jetting isnt that hard and pods are easy to install. In my opinion, i would rather do that, and gain a few ponies and solve the problem then bang my head against the garage wall and read mindless grease monkey opinions on the web. I was just trying to get you a solution the quickest way possible so you can develop carpal tunnel from operating the throttle, rather than the mouse.
I by no means wanted to you to "Clone my bike" and someone else suggested.

Yes, I agree.  Jetting really isn't that hard, especially once you get the hang of it.  On my 77 550K, I can change the main jets with the carbs in place in less than 30 minutes.  Changing the needles with the carbs in place takes maybe another 40 minutes or so, since you have to be really careful with the tiny screws on the slides.  The problem is you have to do it several times to zone in on the optimal settings.  I find it useful to have been too lean, then too rich, then fine tune to optimal.  That way you know the difference.

I use the baffle in my MAC exhaust.  It is just too obnoxious to the neighbors without it.

[scadaman29325]

Woooo dogey! Ehhh, 'thanks' for the replies! (We'er airing out some laundry today!)

I got the idea: too fuel/not enough air, needs fixin'...

Hold on to your jock straps, here's another related question:

Somewhere in this thread it led me to believe I should change the plugs because they are 'sooty', rather than a new set can I clean them and reuse. They are/were brand new. I thought about taking a firm bristled brush and some wd40... (I dismissed the idea of the brass toothbrush because I was afraid of scratching the porceline.)

Thanks to all for the help, Phil

[TwoTired]

The spark plug porcelain is abrasive.  Any metal tool you use to brush off the soot will also deposit a thin layer of metal from the brush into the porcelain surface.  Metal is conductive, just as soot is.
PJ recommends a torch to burn off the soot.  I tried that twice (propane) on a plug and it didn't recover the spark plug.  Replacing the plug solved the misfire issue on that cylinder.  There is a tool that uses silica abrasive grains to clean spark plug electrodes using air pressure propellant.  I don't have one of those.  But, I've used them in the past, and they do work well.

These soot deposits are normally burned off by combustion (when the temp is high enough).  So, I don't know why the torch didn't work.

The porcelain is pretty tough, so I wouldn't worry about scratching it.  Leaving a metal deposit, I would worry about.

You can take a new plug and mark the porcelain up with an ordinary lead (graphite actually) pencil.  (A prank we used to use on the newlyweds car engine.)  It was much easier to follow and harass them when they tried to make their "getaway" after the reception, while the engine fires on half the cylinders.  We left a box of new spark plugs and a spark plug wrench in the car trunk, as wedding presents.

Cheers,

[hapsh]

They should clean up fine to be reused.  Unless the plugs are fouled with wet gas or oil they should still work good enough to get you running so that you can dial in your mixture.  Soot usually isn't too hard to clean with a few shots of Carb cleaner and an air compressor anyway.  Until you get your mixture figured out you will end up dirtying up your new plugs in a matter of minutes.

[edbikerii]

Mileage update:  I got 137.3 miles since my last fill up, and I topped off again tonight with 3.492 US Gallons.  That works out to 39.32 MPG.  This was about 50% highway, 25% suburban roads, and 25% city streets.  I suppose it could be better if I putted along the highway at 55mph for three hours straight, but then I might as well shoot myself.

BTW, I'm pretty sure that is about 5mpg better than I used to get with my stock airbox, but my memory of those days is kind of vague.

[TwoTired]

BTW, I'm pretty sure that is about 5mpg better than I used to get with my stock airbox, but my memory of those days is kind of vague.

Weren't you complaining of running too lean with the stock air box?

 

[edbikerii]

Yes, it was definitely running too lean (and too hot) with those stock 90 mains and the stock airbox.  I guess opening up the airflow and increasing the fuel flow with larger mains made it run more efficiently (at least for my riding style).  Perhaps improved efficiency means I don't have to open the throttle as much to get the required performance? 

http://www.knfilters.com/audio/09%20Mileage.mp3

Or, as I said, my memory of pre-pod days is quickly fading away.  Perhaps I'm way off about the mileage before the pods?   What kind of mileage do you get for similar riding conditions with stock airbox?

BTW, I'm pretty sure that is about 5mpg better than I used to get with my stock airbox, but my memory of those days is kind of vague.

Weren't you complaining of running too lean with the stock air box?