Topic: running really rough, desperate need of advice--- *Problem SOLVED!!*

[Bru-tom]

yeah! Busy resetting my float levels now. Im going to go to 24mm and see where that puts me. Maybe then my Idle Screw will have some effect after that!

I mean, that new needle valve is like maybe 3 times stronger than the stock ones. Maybe i should even go 25mm?

[DustyRags]

AWESOME! Great to finally see some progress! I was getting pretty frustrated, I can't even imagine how you felt!

[Bru-tom]

gees brother, you have no idea im about to test my carbs in the next hour or so, i hope they work

talk about the last place you look hey!

[Bru-tom]

update...I put the carbs on, still a little rough, took em off and set the float another 1mm lower in the bowl and its a little better. The idle screw has a tiny effect now, but not like on my mates carbs i tried.

So, my conclusion is that i need new jets etc to get my carbs up to scratch. I noticed that my one idle jet where the emulsion bit is, was bent and and and... my carbs were eff'd with in their time, i mean, 8 of the 16 float bowl screws were stripped, had to redo all of them to 5mm screws... so i can only assume that the jets were cleaned incorrectly by the PO's to make them larger (particularly the idle jet). So i will order a Honda rebuild kit first thing when they open in the new year and take it from there.

Thanks to all those who helped and advised me

[DustyRags]

Oh, I can imagine the frustration! Still, so glad you're finally on a path forward. Keep us posted!

[Bru-tom]

Yep, thanks mate.

I mean, after all this the next step would be jets? there isnt anything else in the carbs that could be causing this that the kit wont fix? Its like no matter what i do she sucks too much fuel up. And its not like my intake is too restrictive either.

If i cant source a OEM kit from my local agents, what would be the next best kit to get? heard all sorts of good and bads about the Keyster kits, specially the main jets needles...Any where can i source them from?

[seanbarney41]

Honda oem carb kits will not contain jets, but Keihin jets can be obtained separately from many sources, such as Z1 Enterprises...

[Bru-tom]

thanks for that...

Well, i have found places that do sell Keihin jets, but they are expensive. Could i get away with OEM slide needle and the other jets etc of the keyster brand?

so do you guys reckon that the jets can be the only problem? I mean, the carbs are scrupulously clean, so there are no blockages...reckon the slow jets are faulty?

[harisuluv]

Hi again Bru-tom, can't help but think you are going in so many different directions again.

I tried to catch up a bit but one thing in particular jumped out at me as something hard to go off of.  You said:

"The idle screw has a tiny effect now, but not like on my mates carbs i tried."

The idle adjust screw (note this is NOT the four individual air mixture screws on each carb) should have a dramatic affect on the bike.  You can go to high revs to down to where the bike just dies.  If this is not the case then something is wrong there.

You could just be out of sync, but another common problem is that somewhere along the line the sync for the slides was not done in relation to the idle adjust screw.  If this is the case they can be synced but not even contacting the idle adjust screw.  Or, the idle adjust screw only makes contact to give an extremely limited range of adjustment instead of what it should be able to do.

What exactly are the symptoms we are dealing with now?  It is running "rough?" and not responding to idle adjust screw?

[Bru-tom]

thanks Harisuluv for the concern mate,

I actually meant the idle mixture screw, not main idle screw. Sorry for the misinterpretation. The 4 mixture screws on the intake of the carbs is what has little effect on the richness of the idle and still the bike runs very rich. I am at 2 turns out now, still very rich.

My bike seems to be running a bit better since i dropped the fuel height in the bowls, but still i get the blubber. I have paid close attention to the throttle position since. If i am cruising in any gear with basically no throttle applied, and i ease on the gas even a tiny bit, she hesitate and makes a noise like "brrrrrrrr", but if i open past the "just open" throttle position, she rides perfectly.

Sometimes if i am riding and i going at it at nearly no throttle, i pull the clutch in and give the throttle a few twists, she does not rev up cleanly and smokes, only after a few revs, then she revs super again...

[david 750f]

When you first start the bike do all the exhaust head pipes heat up equally?

If you think your float levels are too high, try this.

Get the bike started and then go for a ride. Shut off the fuel supply, the bike should still run for a good 1/2 km. As the fuel is burned off and the floats lower see if it affects your off idle acceleration.

[Bru-tom]

Hi David, yes they do, i do the wet finger test and listen for the "tssss".

Well, my level is at 26mm now. stock it 22mm. I did forget the petcock off once and she ran beautifully until she cut out, then realized id forgotten the petcock off hahaha. but yes, she ran way better then...

thats what doesnt make sense, could my idle jets be fubar because a PO might have fcuked with them? i cleaned the carbs twice now, and meticulously cleaned! im scared if i lower the fuel level anymore, the main jet wont get any fuel. My needle and seats all seal perfectly fine, the spring in the needle are soft compared to that of a mates new one, but i have already compensated....

[harisuluv]

Ok that float level is way off.

You are really hung up on your idle jets being off.  I thought we agreed the other day that you should just swap them from your other set and then you will know for sure.  I would rather that than order new ones, wait for international shipping, and then only to find out that wasn't the issue.

[david 750f]

Bru-ton. If the bike ran better with the fuel petcock off then you are increasing float height. I think you should double check if the floats all move freely on the float pins and that they are set at the same height. Search for the "clear tube method" of checking float heights, it did wonders for my bikes performance.

I've never worked on a CB550, is it possible to put the floats on upside down?

[PGF550F]

Not possible to get the floats upside down, On my 550 the float bowls wont go on with the floats installed incorrecly. Dont ask how I know why

[Bru-tom]

Harisuluv, my mate has been using his bike as a daily and i havent had a chance to get his jets from him.

david 750F- I have checked and rechecked. I havent done the actual float height test yet, i need to make the little plus to screw into the float bowls to be able to do that first.

Not possible to get the floats upside down, On my 550 the float bowls wont go on with the floats installed incorrecly. Dont ask how I know why

no mate, they are spot on, just set lower in the bowl (26mm)



I have another hypothesis.... I have been riding her and loving it more and more, being my first bike and all, and the problem is more pronounced once warm/hot. Which according to all my reading is a direct indication of rich situation. Now, she runs fine at idle, its when i twist the throttle and the needle moves up in the emulsion tube that the problem happens specifically.

so, with all my internals being in shoddy condition adn molested by PO's, could my main jets be off, i mean, PO's could have shoved all sorts of crap in em to "clear" them out and made one or two of em larger than the rest? so when i twist the throttle, some allow more fuel through than others? causing the blubber and hesitation at that specific throttle position?

[lucky]

I've never had to buy jets and wonder how to know you need new ones.   
I would imagine there would need to be a lot of miles on the engine to require new jets.


Edit. I forgot about your modified airbox.

Jets last forever. Unless someone ruins them.

[Bru-tom]

they last forever looking like my main on the end?



I had to re-tap every single float bowl screw to m5 because 14/16 were stripped or well on their way. So what does that tell you? One of my idle jets emulsion tubes were bent at a 10 degree angle. The idle jets flat slots at the top for a screw driver were burred and gouged from being pulled out so many times by PO's.

I fully understand that brass wont wear from fuel flowing through them and will take years and years to wear and only if there are debris in the fuel.

why does my mixture screw not offer any leaner mix when i screw it out 3 turns from fully closed. They are not worn as when i flushed all the air and fuel paths in the carbs for the third time after a complete disassemble and rebuild, they sealed perfectly. I have done everything in the book and beyond and there is no change?

I have adjusted to try correct the problem over and over, but maybe i cant adjust my way out of something that is worn or damaged?

My airbox should be way better than with pods?! that what i read here time and time again about pods being crap compared to stock? so i thought id try something new with my mod and change the stock setup a bit. The bike does not run any better with no filter fitted either, so its not restricting anything.

the carbs i tried that belonged to a mate with pods fitted, were so out of tune, floats were between 22 and 30mm and air mixture screws messed up too. they were dead top end, but i know that because it needs a bigger main jet, its stock 98 atm. they got rid of that blubber though.

I have done ignition timing, just set valve gaps, checked colour of spark etc etc...

i mean, what else is there for me to try??? as mentioned above, it only happens when the throttle is twisted and the main jets needle starts to rise, thats when i get the blubber and super rich mixture. When i feel it happening, i pull the clutch in and give it a little rev and it hesitates and puffs a little black smoke, then clears after 2 or 3 twists of the throttle to say 3000 rpm...

[harisuluv]

Idle to 1/4 throttle is slow jet territory. 

Lucky is correct in that the brass will last a long time but that's IF they haven't been abused.  IE someone tried to clean them with the wrong tool, or they were drilled out, or in general, messed with.

You can try new slow jets, it's not going to hurt.  This thread is starting to get really hard to follow too, might be a good idea to consolidate and list what you have done/haven't done.

Also, I think it's unfair to compare your airbox to a stock one, it is in fact, modified, by definition it is NOT stock.  Does it have a filter on it at all now?

[Bru-tom]

i understand that the slow is responsible for idle to 1/4, but then what happens when the main needle starts to rise when you twist the throttle?

I know that they cant wear, but there are signs as mentioned previously, that PO's have messed with the carbs a lot, hence the stripped screws etc. Its the first freaking place noobs want to fiddle with

did you look at the main jet in the pic and how screwed up the head is, they are all pretty much like that. That tells me that they could have shoved anything in the holes to try "clear" them...

i do understand its modded, its not stock, but as far as im concerned, its closer to stock than pods. the air still has a little more time to settle down before entering the ram tubes or whatever you call them. i do have oiled filter material in the box atm.

My problem is, that i need to buy carb kits to be able to replace the slows, as much as id like to use good second hand ones. but ordering from abroad is a pain and i can only get kits in SA, which are not to the original standards as we all know. unless you can hook a brother up with special special festive discounts

[harisuluv]

There's no oring on the main jet in the picture did you take it off?

[TwoTired]

I just read this from page two...whew.  What a confused and jumbled mess.

Some thoughts that might help... 
Too high of a float bowl fuel level will make the the idle RPM range very rich.  The upper range too, actually, but the since the air volume is higher at higher RPMs, the extra fuel contribution is less significant.

The float valve spring pins are supposed to be soft (and equal among the four carbs).  Aftermarket substitutions often build for appearance rather than function.  And stiffer springs pretty much guarantee the book value mechanical float settings will be wrong.  I'm not convinced your float bowl level has been correct from the get go. 
Use all stock float valves and stock float mechanical settings.  Or, use the stiffer springed float valves and use the clear tube method for determining the correct fuel height in the carbs (about 1-3mm lower than the gasket surface, again equal among the 4 carbs.  This is a mixture tuning operation which has impact at all throttle settings, but is usually more significant at idle position and speed, particularly if too high).

Since you refuse to use the stock induction and exhaust components, stock book values will no longer apply to your bike, and you will have to custom tune your one-off assemblage of components.

Open pipes reduce back pressure at the exhaust valve, increasing gas scavenge from the cylinder.  This can allow more oxygen to be present in the chamber, requiring a slightly richer mixture delivery by the carbs.  This is only one variable you added, btw.  98 mains were used on the CB550F model, with a high pressure exhaust.  And an open exhaust brings it closer to what the K model had with 4 pipes.  Use at least K model carb setting specs (100mains/ slide needle in the 4th position from top) to begin your custom carb tuning, as you must also compensate for the induction mods than have been made, which normally raise carb throat pressures, which reduces fuel jet delivery volume.

98 main carbs from the factory were stamped 069a and had solid tipped pilot screws.  What do yours have?

Slobbery rich mixtures can quickly foul spark plugs.  Then it will run badly because of the plugs AND the mixture issue.  Fix the plugs and a temporary improvement can be noticed.  Fix the mixture and it won't run better until the plugs get clean.

I recommend you fix the bowl fuel levels first and move away from the Stock F model carb set up. (assuming you have no intention of returning to stock exhaust and induction components.)

Do the spark plug deposits show the same deposit pattern on each and every plug?  You can forget about fine tuning for mods until this needed trait is established.


Change 20 things and you add 20 more variables to juggle.  Does that sound easy?  What is your present change count?

[Bru-tom]

Hey fellas! Yes, i know its an old thread, and its an old thread....

Thanks TT for the explanation above, only saw it now..

but i come to you today with a solution, a real one! or a few, depends....

Here are detailed closeup pics of my original jets and needles...

idles:



Mains...as you can see, they are pitted, corroded and mangled...







my needles, worn and seen better days. You can see the light spots (worn spots)..



needle tips, you can also see dark spots on places:



the right two, you can see swirl marks near the tips, gouged almost.



The needles defo have a texture to them, like machining marks from a lathe if you may. The lights spots are where the texture is worn off.



so here it goes....

A HUGE thanks to harisuluv for his help with supplying me with near brand new second hand idle jets, main jets and needles in fantastic shape!

After a month of impatient waiting they arrived. My local PO had a strike, so awesome!

i stripped my carbs for the last time (in my head). There have been too many unproductive times that i really was/am fed up to be honest, nothing seemed to have worked over and over and over again. If it wasnt for my inner perfectionist, i would have given up already. So i stripped all the old junk out, fitted the new. Had a couple of needle securing screws head strip, had to drill the heads off and unscrew what was left of the thread...but all in all, a success. float levels are set at 23.5mm now as apposed to 26mm i had it set on previously in an attempt to kill the rich condition.

Slapped em back on, spent a few hours servicing the bike and carb synching....immediately i noticed a pitch change in the zhorst tone...the bike seemed to run leaner at idle, so this was a great sign. she revved cleaner and smoother....

So, obviously, we had bad weather! i had to wait an entire day to test my "upgrades"......right off the bat, the pull off is far smoother (med engine temp).  Ran the bike through the gears for a couple k's till warm. This is when the problem was most evident. And the hesitation after decelerating to 0 throttle from 3/4 and back onto the throttle to 10-20 percent for a few hundred meters slowly increasing / snapping the throttle open...the hesitation and blubber was damn near gone!!!! I could not believe it, i had a smile on my face for the rest of the ride, shouting whooohooo and and and...it was a fabulous feeling! Really great to get something right after so many fails...

The filter mod is also not affecting anything, nor my zhorst setup. the bike runs even better than before. I almost feel as if all the stuff i replaced needed to be and had an influence with the way the bike was reacting previously.

Thanks again to Harisuluv, highly recommend his services...

Bruce

[MoMo]

  congrats...Larry

[harisuluv]

Wow, good news.  I'm glad you followed up cause this always seems to happen with the 500.  Must be a relief, keep an eye on it and let us know if it changes.  Your welcome, and thanks you