Topic: 1978 cb550k uni pods and 4to1 mac exaust carb tuning ....help!!!

[screemn2]

rebuilt carbs 105 main jet timing set to spec valve lash set to spec cannot get this thing to run right ...not even some what drivable...starts first kick as long as you hold the choke shut and flutter it ther after to keep running...i am ready to light fire to this thing ..ive tried all i know to ...if anyone has any ideas...please help me ....sincerely "the lost one" floats set to spec as well 13mm as they are the pd46c set to the bottom of the float..

[DaveBarbier]

If you need the choke on to make it run better then you're too lean.

Factory PD46C float height is 12.5mm. BUT, you must verify the fuel level in the bowls with the "clear tube method" - search for that in the search bar. Fuel level should be about 4mm below bowl seam even if your float heights are varied. Is the only thing you changed in the carb the main jet? Did you use Keihin jets or aftermarket? Your needle position should be changed too. What about your IMS? Did you sync the carbs? Are you 100% sure the carbs are spotless inside? Here are my settings with the same bike and pretty much identical mods with a stock motor.

IMS-1 turn out
Main Jet-110
Slow Jet-45
Float Height-varied (All fuel levels 4mm from bowl seam)
Needle Setting-3rd from top

I only increased from 42 to 45 slow jets because I couldn't use my stock ones and I had some 45's lying around. You could stick with the stock 42 and maybe bump up the IMS to 1.5.

You mentioned timing set to spec and valve lash but what about cam chain adjustment? Set your point gap before timing? All that should be done before carb tweaking.


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1978 Honda CB550K

[harisuluv]

Tell us about your bike.  pod filters, stock air box?  exhaust modifications?  What did you do to clean the carbs?

[screemn2]

thanks guys .. i just changed the main jet and that was it to the 105 witch seems to be the norm from all that i have read and did leave the slow jet at the stock 42..ive put the idel screws about every were not really any changes in anything ....the bike it all stock except for the uni pods and the mac 4 in 1 exhaust . i totally went through the carbs ....like twice ive done everything like twice ....im lost and bummed  ....valve lash timing all of it ...cleaned carbs e string guitar....spray you name it ....all cylinders are running about the same temp when i check at the exhaust outlet....i cant imagine what the heck is goin on ....ready to cover it up and forget about it...good greif....thanks for any help you guys may have it is much appreciated ..

[screemn2]

i never touched the cam chain adjustment as i got it running prior to tearing it down when it was in stock condition...it wouldnt idle then cause the float height was set wrong at the 22mm when the po couldnt get it running right now they are all at the 13mm...but beyond idle it had fine throttle response .. and yes the point gaps are proper as well...i measured the float height at the bottom of the float ...right?the needles in the carbs are in the stock positions second or third notch down....i just cant imagine that it wouldnt at least run somewhat proper the way it is set right now ...fine tunning ..sure ...but to not be even some what drivable ...errrr....but i am new to these bikes ...the cb350 ive got wasnt nearly this difficult

[DaveBarbier]

ive done everything like twice ....im lost and bummed  ... ...i cant imagine what the heck is goin on ....ready to cover it up and forget about it...good greif.

Get a hold of yourself!

Do you have a manual? If not, you can download one here.
http://www.honda4fun.com/materiale-documentazione-tecnica/shop-manual

Don't freak out, if I was at your bike right now, this is what I'd do to make sure things are in working order. I implore you to go over these again. This list is from OldSchool_IsCool, but I shortened it and edited it a little.

On a cold engine in this order:
1 set cam chain adjustment
2 set tappet clearance
3 clean points & set points gap (both sets)
4 static time
5 verify float height (see below) *
6 once running verify timing dynamically with timing light (idle and advance)

* Also, did you verify fuel level in bowls with the clear tube method? Do NOT just assume it's right by setting the float height. Post pictures of your results. This is what they should look like on all carbs (that strip of paper is 4mm in height):


Do ALL of this then come back. If you're going to burn your bike, don't, I'll buy it for the cost of the gasoline you'd use to set it ablaze.


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1978 Honda CB550K

[screemn2]

thanks for all the info dave ...will do the float height first considering the bike ran so much different at the 22mm the po had them set at ....could that really be the problem in itself from what ive been telling you ? ive got so much time into this thing being i tore it down to the frame and cleaned and renewed the hole thing ...hope to get it at least drivable before to long so i can move on and finish

[DaveBarbier]

the needles in the carbs are in the stock positions second or third notch down....i just cant imagine that it wouldnt at least run somewhat proper the way it is set right now

My settings work pretty damn well on my bike. Nice power and throttle response. The member who replied above, Harrisuluv, suggested those settings and if you don't know, he knows carbs very well. He mentioned needle setting was very important, so after you check the stuff from my above post I'd open the carbs and make sure they're in the third position from top.

Also, is your tank clean? If you drop your carb bowls is there any sediment? That could easily clog up your jets.


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1978 Honda CB550K

[DaveBarbier]

thanks for all the info dave ...will do the float height first considering the bike ran so much different at the 22mm the po had them set at ....could that really be the problem in itself from what ive been telling you ?

It could be an issue, yeah. You're running lean and a lower (22mm) float height, as opposed to the stock 12.5mm, will create a leaner condition. (Edit: I meant higher float height, but raising float height lowers fuel level in bowls)
Also, raising the needle by lowering the clip position will make it richer still. Might be just what you need. BUT, I'd still do the super easy job of setting cam chain adjustment. Then you could just verify the other settings. Let's say the float height and needle position fix your issue...it might run better still by adjusting cam chain and doing the other 3k mile tune up stuff.

Not sure I said this, but changing needle position requires a carb vacuum sync.

Good luck


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1978 Honda CB550K

[Deltarider]

Be methodical!

Why not start by verifyingc what bike you have? Write down your engine-, frame and stamped in carburetornumber. Why? Because a 22mm floatheight is ridiculous for the CB500/550K3s PDcarbs and 12,5 or 14 mm is likewise ridiculous for the oldstyle Keihin carbs. Don't bother us with 'year' but describe first what model you have and what is not original anymore. In the various Parts Lists you'll find listed per model the corresponding engine- and framenumbers as well carbnumbers. It's in the first pages of every Parts List. Very simple. You'll find forsaid Parts Lists here: http://www.honda4fun.com/materiale-documentazione-tecnica/parts-list/parts-list-cb550
In the Original Honda CB500 - 550 Shop Manual you can find the settings for the different carbs*. That manual is to be found here: http://forums.sohc4.net/index.php/topic,17788.0.html
Unfortunately page 7 and 8 are missing that have important information about tappet and carburetor adjustment. If you need pages 7 and 8, at this Italian site you find the same manual, uncorrupted, be it in a poor resolution:
http://www.honda4fun.com/materiale-documentazione-tecnica/shop-manual . I advise you to select the one with 'Courtesy of Tums & STENK3'.
So from now on we'll have no more talk of year this or that but everybody will know exactly what model he has so we can have things straight. And there will be no more questions that you could answer yourself by consulting forsaid documents. For the rest we will be glad to help you. Ipse dixit.

* If your carbspecs are not in there, we can help.

[screemn2]

This is were all the carbs are at in fuel level ... could this really be the problem?....and now am i suppose to take the float height from the 13 they are at to like 15 to bring the fuel down a little bit ?

[harisuluv]

the PO set the floats at the setting for the earlier year carbs then.  They have a setting of 22mm, which is way different from 12.5/13mm.

You should post more pictures of your carbs off the bike, all angles.  You will get real help then.  Sounds like you have backwards slides or something.

[screemn2]

thanks haris ...what is the slide?...the little barrles?i will take more pics and post

[screemn2]

These are some photos...is the short side of the barrels suppose to be on the air box side and the long side of the barrel suppose to be on the intake manifold side?....does anyone know ?  thanks

[DaveBarbier]

I'd wait to confirm from Cal and Harisuluv, but to me, that fuel line routing isn't ideal. Should be a more direct route without the fuel going up hill.


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1978 Honda CB550K

[screemn2]

A couple more photos

[harisuluv]

Well you're going in the right direction, we can see kind of what we are working with now.  I don't know if it's me but the pictures are kind of hard to make out.  The fuel line/routing are definitely not optimal.  Is the tank moved from stock position or something or higher/lower?   Is it a 550 tank for your bike?

It doesn't look like your choke spring connection 1/2 to 2/4 is attached.  Does your choke work?  Does actuating it from where the cable would attach operate all four choke butterflies simultaneously?  After blowing it up and trying to look at it, it's hard to see, but it looks like the spring that is supposed to be there isn't even there.

Starts with first kick as long as you use choke--ok... so that's pretty normal no?  Use choke at cold start and then once it's warmed up you turn it off.

Where are your pod filters?

Here is a picture of the choke assy together.  Notice there are two springs, you seem to be missing the one on the right.

[screemn2]

yes that little spring is gone as i spot welded the two rods together and the choke is only using the big spring .....but back to the little barrels ...the longer side of the barrel is for surely suppose to be on the intake side and not the air box side right ?... those barrels have an extra hole on the top of them and this is not suppose to be covered up?....i have the carbs back apart once again...i thought that they were maybe put in there wrong by the po as i put them together the same as they came apart...but at this point im gonna try anything seems as if it should be running now

[DaveBarbier]

When the slides are in the body, the cutaway (the angle on the bottom of the slide) needs to be facing the air filter(s). In the picture where we see the profile of the slide (with the clothes pins and the candle in the background) the engine would be on the left and the air filter(s) would be on the right. I don't know if the hole you're talking about would be covered or not, but the slide must be in this orientation.

What are your needle clip positions?


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1978 Honda CB550K

[DaveBarbier]

thats high. But your jets are too large too.

Oh, I was under the impression he was running lean because of what he said about the choke. I usually don't know what I'm talking about so I'm going to stick around to learn something, haha.


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1978 Honda CB550K

[xtravbx]

thats high. But your jets are too large too.

Oh, I was under the impression he was running lean because of what he said about the choke. I usually don't know what I'm talking about so I'm going to stick around to learn something, haha.


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1978 Honda CB550K

Don't worry you're not alone..

[screemn2]

The needle positions are at the second skot from the top...i beleive that is the factory setting

[harisuluv]

You've asked me a couple times via pm and in the thread the answer is the same, the cutaway does go airbox side, it's right, move on.

Spot welding the two choke sides is bad.  Hope you got it perfectly aligned.  People disassembling/reassembling still have to adjust them when they bind without them welded together, with them welded together, kind of makes it more difficult.

Any other custom mods we should know about?  You have people taking the time to help you, if you don't disclose things you know like this, it's not going to encourage people to continue helping you with filtered/partial info.

P.S.  Please take/upload pictures that aren't sideways

[DaveBarbier]

But your jets are too large too.

Oh, I was under the impression he was running lean because of what he said about the choke.

Dave- The other reason I stated this is due to the fact that stock main jets for his carbs are 90. He went straight to 105. Thats a big jump, and given that his bike won't idle, the main jet issue isn't even involved yet.

I get that he wanted to "tune for final" settings out of the gate, but given some of the apparent issues, I'd return to stock jetting, get the bike running. Decide if/how lean it is, then proceed with larger mains. It is sort of what you did, correct?

Ok, that makes sense. And, yeah I tried to do that, but going stock for me was still crazy rich pilot jets because they were drilled out by the PO. So I didn't really get anywhere with that, ha.


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1978 Honda CB550K

[screemn2]

Thank for all the info guys it is appreciated...aside from the exhaust and the pods the bike is stock....i was really hoping that the slides were in backwards and that was the. Problem...the choke was spot welded visually perfect....i guess im gonna throw the carbs back together. Bring the fuel level down a little bit from were it isright now...and after that doesnt. Work. Itll get covered up or sold unless i take another intrest in it....thanks to you. All again.......signed "the cb550k has fried my brain"