Topic: CB500 problems carbs 4into1 / 4into4 experiment

[TwoTired]

"The point is, why must you have the carbs tuned so far from factory specs?"

This is exacly the question I am seeking an answer for in this forum! I have tried two different new air filters and new pod filters and there is definately no obstructions to the air flow. I have sprayed wd40 around all the connections between the new boots and the carbs/manifold/engine with no effect to engine idle speed.
Believe me I would love it if it would run with everything at factory spec. settings and sizes!

--- Cylinders 1&4 run cooler because they only have one adjacent cylinder and have far more cooling fin area.    If the cylinder is generally cooler, it will be harder for the spark plug tip to maintain proper deposit burn off temperatures, and thus accumulate carbon deposits.

The fact that you can modify the settings of your carbs to approach proper run mixtures pretty much says that it is the carbs that are not performing to factory new spec.
It is going to be difficult to find out what is not meeting spec, without measuring the components that exist inside your carbs.

--- It is expected that changing the exhaust functional parameters will change the engine's demand for mixture ratios for these carbs.  Honda used this carb model on different bikes and changed the internal set ups when displacement was increased and when the exhaust parameters were changed.

--- I've gone through the pilot screw optimization routine on several CB550's and each time, as long as the induction and exhaust components were stock, the pilot setting came within 1/2 turn or less of what the book stated for that model carb.  (The spec did change with with the model.)
The F model bikes came with solid tipped screws, but also had a different taper angle and seat style.  The drilled screws of other models were a limiter to the adjustment range available.  However, they still had plenty of adjustment range when used with the bike's stock components in proper working order.  Certainly filling the holes would require turning the screws outward from spec to restore proper air bleed flow.

[harisuluv]

Can't say that I remember many specifics that would help immediately.  I don't have any correspondence records, looks like ebay (where transaction was made) only keeps them from last 6 months.  Searched my SOHC PM inbox and didn't see anything.  If I still had the messages I might be able to remember anything out of the ordinary or issues.

All I have for definite is the album, which dates the rebuild at 5.17.13.  I do remember being contacted about running rich and sending out the 4 aftermarket needles to australia at my expense, but haven't heard about anything else til now, where I was contacted via PM by another member trying to assist.

I had a similar issue once or twice where that fixed things.  We all try to reuse the OEM needles, but that isn't always possible, occasionally they get worn.

I'll try and be of any assistance that I can but will have to read through the thread a little more thoroughly later.

http://imgur.com/a/hgN7z

[dave500]

you must vacuum sync any carbs full stop,a bench sync,a good bench sync or any bench sync is a ball park get you running well enough to run the engine sync and that is all a bench sync is full stop,if you pull the needles you disturb them enough to require vacuum syncing again full stop,go over your ignition again,use a timing light etc,oh #$%* that just bring your bike and some beer over here and ill have a look at it i cant stand it anymore!

[Deltarider]

It would be interesting to know how manufacturer Honda synchronized their carbs. I've always been succesfull in bench synching (well within 2 cm Hg). 

[dave500]

you just got  lucky delta!try the carbs on another engine?

[jonda500]

Have wanted to own a set of vacuum guages like forever - they are on the very top of my wish list now and will be the next thing I buy for the bikes! (i have looked at all the different home made versions that you can make but I've decided I'd rather save up for a good quality set that I will always have for easy future use.)

[Deltarider]

you just got  lucky delta!try the carbs on another engine?

Than I've been lucky at least three times. I have never tried the carbs on another engine but... what I have learned from an old mechanic is that in his experience specifically the CB500 was the most sensitive for synch of all the SOHC models. Don't know why this is.
The point I like to make is this. First ask yourself how likely it is the PO ever synched or messed with the carbs. I mean, a lot of bikes that appear in this forum are practically in a virginal state if I read about the miles on the odometer. Given the fact that Honda did the utmost to design the combined carbs to work troublefree, you should be damned sure the problem is in the synchronization. At times I did over 50.000 kms without checking the synch and whenever the engine would run a little rough, the cause was always elsewhere (mostly ignitionrelated). Just my experience.

[dave500]

its not so much the messed with stuff but the fact that parts wear out,the vacuum pull from each cylinder at idle will never be the same even on a new engine delta,this isnt important when your hauling hard in third or fourth gear or what ever but at lower rpm and high vacuum the lower rpm speeds need it properly balanced,youve been lucky!the imbalance of vacuum causes that #$%*ty rattle as the cylinders fight at idle,at idle the fight is hard,once rpm builds up the difference in power between the cylinders becomes less and they all pull the same and the fight is forgotten,they must pull together at low rpms,vacuum sync wont do #$%* all for peak power from any engine,but if you want a decent smooth quiet idle and a good transition in power from idle to mid then power range you really need to vacuum sync your carbs,if you think you can guess it your guessing wrong!syncing is balancing the vacuum signal between each cylinder,not what size drill bit or ball bearing you can get each slide to stop at,fair dinkum!

[jonda500]

By the way this bike was running absolutely fantastic a week ago before I removed my carburettorkeith carbs and started trying to make it work right with it's original carbs back on!
   The carburettorkeith carbs were working great with the four into one & straight through muffler fitted and the jet sizes and settings were:
 #100 mains, #38 pilots, mixture screws 2 1/4 turns out, needle clips #2(from top), standard air filter.
They came already vacuum synced(but not fitted to my bike when done!?) but initially had #40 pilots and #4 needle clip pos.(this is because I requested them to be set up for my 1st honda)   

[dave500]

you cant go too far wrong with 38/100,or 40/100,you havent got like a piece of rag spare under the seat getting sucked in to the intake?

[dave500]

they cant have come already vacuum synced,who told you that lie?

[jonda500]

you cant go too far wrong with 38/100,or 40/100,you havent got like a piece of rag spare under the seat getting sucked in to the intake?

Ha ha - no but that is a fair call - I once thought I had a major problem with my RZ250r whilst on a long trip and took it in to a yamaha dealer to be fixed. Turned out when I last topped up the two stroke oil under the seat I was a bit careless about stowing my oil rag and the motor had sucked it into the air intake orifice! The shop still charged me for a ficticious muffler re-pack though! I pulled the mufflers apart when I got home and they weren't the packed type, they just had metal baffles which hadn't even been cleaned!

"they cant have come already vacuum synced,who told you that lie?"
Go to ebay and check out carburettorkeith 's cb500/550 carbs. (He fits them to a bike and vacuum syncs them as part of the rebuilding them)

[dave500]

ok so he doesent lie in a round about kind of way,but they are synced for that engine if he syncs them at all?dodgy dodgy dodgy!very #$%*ing dodgy!man?hearing this #$%* really brings me down,you meet people on bikes in our circles,and they tell you this same stuff,so i have to explain #$%* and they almost say like,who the #$%* are you or have a blank look,and they dont even own the cheapest of socket sets?let alone know what a jis screw driver is?ah who cares,their dumb luck,or judgment?ill help anyone who needs or wants a hand.

[jonda500]

Thanks everyone, I am very grateful for your assistance and I do value everyones input! I feel this site has given me a light at the end of the tunnel and sincerely apologise if I'm #$%*tin you all to tears - I became so frustrated with removing and refitting carbs 6 months ago that I had to give it a rest until now, I tried to put it right out of my mind and focused on the many many other parts of my 3 bikes!
   I am ready to be very patient and methodical now and will keep you updated on any progress

[harisuluv]

I read this post from you from a different thread:

"my carbs were rebuilt by harisuluv, whenever I hook them up to fuel after they have been dry for some time fuel pisses out every where (except the overflow tubes!!?) but after ten minutes or so they come good and I can leave the fuel tap in the on position all day with no sign of a leak! My theory is that my float hinge pins are so tight that the floats wont move at first but after a few minutes fuel seeps in and lubricates the float hinges. (Oh and yes I realise that I need to check my drain tubes for blockages)"

This is very much so relevant information and am surprised it wasn't brought up. Every set I rebuild gets the overflow tubes checked twice and blown out with compressed air. Your overflow tubes are clogged.

This is however, only a symptom of the problem, your floats aren't cutting off fuel. If your float level is so high that it is spilling out everywhere, then it's going to result in a rich condition.  Float levels are off or are not functioning properly.

The float is not fixed to the pin. It can swing perfectly independent of it. I could epoxy the pin in the posts and that wouldn't matter.

I probably woulda just sent you out new valves and then you could have double checked the level and been on your way.  Seems like so many parts have been swapped now and I'm sure my original bench sync is not what is used to be.

To be totally honest and dare I say frank.  Like I said I didn't have the transcript of our correspondence, but looking over it I pretty much offered you unlimited technical help and looks like I offered to send you a completely different set rebuilt and I would pay the shipping back to you ($75) as long as you sent them back to me.

In our correspondence I mention this or that I.e. Vacuum sync or I think it's x or y and you never do the sync and the. In some cases just plain say " I don't think its that. "

I sent you new needles as a precaution then never heard anything back from you until 6 months later.

[jonda500]

At the time when I asked for new needles & main jets to see if it would help these carbs had not had any leaking problems(since being rebuilt)

The floats / needle&seats only very briefly allow leakage after sitting dry for extended periods which is why I thought the floats were perhaps a little tight on the pins, I have a drain plug with a clear tube attached so I will check the float bowl fuel levels (and check the drain tubes for blockages).

I am currently saving up for a set of vacuum guages.

I decided I'd like if possible to keep the bikes' original carbs on the bike as they (visually at least) are a very nice original set, but the main reason I didn't send them back was the expense!! Austraila post costs close to double what it costs in US(it cost me nearly AUD$140 when I originally sent them to be restored and I can't easily get my hands on that much money!).

It is my understanding that problems caused by unbalanced carbs occur at small throttle openings and lessen as you open the throttle, making virtually no difference at full throttle. When I said "I don't really believe this is just a syncronizing issue" I didn't mean to imply that the carbs don't need balancing, just that as they are unsatisfactory at all throttle openings it is not the only issue they have!

Six months ago I became totally disallusioned and depressed after nothing I did seemed to be helping with these carbs  and since the feed back time limit had expired I just gave up believing I'd ever get these carbs to work for me.

I wont ask for more help until I have saved up and purchased a set of vacuum guages, checked the float bowl drain tubes, checked the float bowl fuel levels  and synced the carbs, thanks, John

[dave500]

is there anyone local to you with a set?might be able to use them.

[jonda500]

Unfortunately I have way more tools, knowledge and passion for these old hondas than any one that I personally know locally- In fact I haven't ever had any help locally with these bikes. Don't worry though, as long as I am still alive I'm gonna keep doing my very best to restore, preserve and maintain my three much loved old hondas - sure would help if I had more money or a job though!!

[dave500]

ill give you a job,come and mow whats left of my lawn,its about 42 deg here right now!

[harisuluv]

"Six months ago I became totally disallusioned and depressed after nothing I did seemed to be helping with these carbs  and since the feed back time limit had expired I just gave up believing I'd ever get these carbs to work for me."

You'll have to forgive me, but what does the allowable time ebay gives for feedback have to do with anything at all?  And furthermore, what does that time period expiring have to do with me helping you?  Do you think that after 30 or 60 days or whatever the time limit is I don't help people anymore?  That's pretty insulting. 

So if that time period had not expired then, it was still ok to contact me?  Or was your plan to give me negative feedback, or hold that over my head for something.

Look, I try to help someone if I was involved in anything I did for them.  That is not time dependent, and definitely not dependent on something as silly as ebay feedback. 

This is the last correspondence I had with you:

"I know it's frustrating but you'll have to work with me as I am willing to help you! We can fix this, so let me know your thoughts on how to proceed - harisuluv"

I am baffled as how you would never contact or ask me for help again. 

Here is what you another quote from your own supplied correspondence: 

"I have checked the choke butterflys are operating properly and there is nothing restricting the airflow to the air filter. I have checked the float bowls are not flooding. This bike I took on a 200km ride a couple of weeks ago and it didn't miss a beat and was idling just fine- however I still intend to install new points condensers and ignition coils tomorrow just to be sure I don't have other faults confusing the issue!"

And now you say:

"It is my understanding that problems caused by unbalanced carbs occur at small throttle openings and lessen as you open the throttle, making virtually no difference at full throttle. When I said "I don't really believe this is just a syncronizing issue" I didn't mean to imply that the carbs don't need balancing, just that as they are unsatisfactory at all throttle openings it is not the only issue they have!"

[luap]

These some good reading on bench synching the carbs until you have the money for the correct tool,
An isn't synching the last step in carbs, clean rebuild, re jet , ride, re jet ect then synch
If you had/told Haris that the carbs were being rebuilt for a 500 you cant get mad when they don't work on your 550. My expierence 40 will foul plugs non stop on modified or stock 550's,
Correct me if im wrong but isnt stock jetting on a 500 carb  40/98
Six months ago I became totally disallusioned and depressed after nothing I did seemed to be helping with these carbs" from reading it doesn't seem like you were working on the problem but looking for a solution by swapping pipes, 500 to a 550, an putting on some pods.
I would pick a bike  pipe an filter setup you want to run an stick with it
get the bike to idle without fouling the plugs, If your fouling at idle first place to start
idle good, ride it through mid range see where your at, from my bikes 3 clip has been the lowest( highest out of main) ive been, If it need to be richer I start oiling pod filters, starting very light an working heavier, riding bike each time the same way- cold temp to warm to damn hot plays a part in jetting also, least in arizona
then see where your at 3/4 to wot-
feel the ride instead of having the book tell you how its suppose to ride.
If nothing else work take dave500 up on his offer he can get it riding for you, best of luck

[dave500]

have you tried new 7 plugs and new caps yet?

[harisuluv]

I don't feel like you are really malicious about it, however, you surely went to leave feedback and at that point found out that it was too late, or else how did you know that the time window had expired.  You intended to leave feedback and it for sure was not positive cause you said that you would have left positive feedback if issues were resolved and they were not yet.  So I can only assume that you intended to leave me bad feedback.  And I'm sorry, but I did not provide a lack of support.

Look, yes you did insult me, and I accept your apology.  I am not infallible, and no one is.  I have been willing to help you in the past, and am willing to help you now.  But if it's going to happen after your very vocal airings, then you're going to have to listen to people.  And you're going to have to be coherent about what the ACTUAL issues are.  There is just TOO MUCH contradictory information in everything you have said.

You need to regroup, and reassess.  That being said, you have made so many modifications to the carbs that they are no where near what they were in their original condition when you got them from me, and for sure any bench sync that I did is now non existent.  Find your original OEM needles that you replaced, put them aside.  Then sort out your float bowls.  Your overflow tubes (the rubber ones) are clogged.  This means your float level is TOO HIGH.  When you have a fuel level so high it starts coming out the intakes then you have a real problem.  This is going to cause you to run RICH.  This makes you foul your plugs, this will make your bike run #$%*ty.  START here, and please, please, start there, and seriously forget the other stuff.  Float level.  Verify valve operation.  Clear overflow tubes so you aren't pissing all over your bike all the time.

Again, I accept your apology and I'm not mad, I've just never had someone make it so difficult to help them.

"Help me, help you." - Jerry Maguire

[jonda500]

I did briefly have the carbs on my 550F just for curiousity and for its 1st test ride, but they are definately for my 2nd cb500. However I did initially fit them to my 1st cb500(4into4's). I guess I did that because that's what I thought the settings would be most suitable for and I was keen to be able to leave POSITIVE feedback on ebay.


   
"I have checked the choke butterflys are operating properly and there is nothing restricting the airflow to the air filter. I have checked the float bowls are not flooding. This bike I took on a 200km ride a couple of weeks ago and it didn't miss a beat and was idling just fine- however I still intend to install new points condensers and ignition coils tomorrow just to be sure I don't have other faults confusing the issue!"


   Back on June 2nd when I wrote this to hari the carbs were on my 1st 500(4into4's) and the 200km ride where the bike was running fine was with the bikes original unrestored carbs still fitted before I had recieved the rebuilt carbs!

[harisuluv]

Jonda, I cannot follow all the swaps and changes done with the carbs, not to mention all the inter-bike swapping.

If you want to argue more and are unhappy, I suggest you do it via PM.  This no longer has anything to do with the topic.  Now, if you want to continue to argue here then go ahead and I will consider it your vendetta to very publicly air any grievances you may have.  In that case, I will retract my offer to further help you.