Topic: pods 4-into1 with idle surge VIDEO POSTED help

[b5rider]

Hello,
I used the search function and couldn't really find a good answer to my issue.
I have a 1978 CB550 with a fresh top end rebuild @<100 miles, Uni-pods, 4-into1 exhaust, and carb rebuild with the following settings :
Pilot jet: 45
Main jet: 95
Needle Position: 1 clip richer from middle position (4th clip down from top or 2nd up from bottom)
Float height: 12.5mm
Air/fuel mixture screw 1-1/2 turns out
ISSUES:
1. Idle surges to @2000, sometimes 3000, RPM after warmed and choke taken off. Intermittently settles to normal after blipping the throttle 3-6 times.
2. When blipping the throttle, RPMs initially lower a bit, then the engine responds by raising RPMs
3. Since the rebuild is so new, I don't want to rev it too much
4. Drives fine with good response (up to 5k RPM-I've not taken the engine higher than that due to the new rebuild

Any suggestion?
THANKS

[ekpent]

Start by spraying some carb cleaner around the intake manifolds to check for air leaks while running.

[iron_worker]

Sounds lean to me and that is usually what happens with pods. Try turning your mixture screws to their full rich setting (not sure if that's in or out in your case ... some have air bleed screws: in is rich ... some have fuel screws: in is lean). If the issue gets better than you have found your problem.

IW

[flybox1]

can you really check for a vacuum leak with pods?   

[Airborne 82nd]

can you really check for a vacuum leak with pods?   

Interesting question even with pods I would think you would hear (ear) or see (tach.) a rpm change. Just asking??

[b5rider]

Just bought carb cleaner. I'll report out thanks

[flybox1]

can you really check for a vacuum leak with pods?   

Interesting question even with pods I would think you would hear (ear) or see (tach.) a rpm change. Just asking??

with such little filter resistance thru the pod, would/could there be enough vacuum at a boot to inhale the spray? 
yeah...just asking 

[b5rider]

I sprayed the connections between the carbs and the engine and the idle started the same

[b5rider]

Stayed

[ANDY W]

i run 100 mains and 3 1/2  turns out on the idle screws w/ uni pods and 4 into 1s. when the rpms jump up at idle just close the choke a little, if the rpms go down then ur running lean at idle. which sounds like u r

[b5rider]

Thanks. The carbs were vacuum synched and set up in Chicago. Dont know what, if any, changes would have to be made for SoCal

[b5rider]

Yes

[DaveBarbier]

My carb settings on my '78 550K are as follows:
(UNI Pods - 4-1 w/muffler)

IMS-1
Main Jet-110
Slow Jet-42
Float Height-12.5mm
Needle Setting-3rd from top

I don't post this to say you should change your settings, but just so you can see what another very similar bike is set up like. Mine seems to run really well.

But I'd listen to Cal and other people when they suggest other things first before carb settings.

Any idea if this was happening in Chicago?

Edit: Oh yeah, I had an idle surge for a while and was chasing air leaks and the advance mechanism to no avail (might want to look into the advance mechanism, by the way), but for me it was crazy rich pilot jets and carb sync. My pilot jets were drilled out by the PO to about triple the size.

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1978 Honda CB550K

[ANDY W]

correction i run 110 mains. what carbs do u have? if they are pd46c the slow jet should be a 42. i tried to run a 45 and could never get it to idle right even with the idle screws all the way in

[b5rider]

Thanks. I believe they are the original carbs. They look just like the ones on my '75 550. The timing, valves, and cam chain were all adjusted to specs before out was delivered. I was going it was something simple, but it looks like I'll have to change some needles. It is my understanding that a surge means a lean mixture. So, any thoughts as to what I should change next?

[b5rider]

Here is the left side of the carbs

And right. Which is the air mixture screw?

[DaveBarbier]

Weird, I think they normally have the model number stamped on the side right under the PD...mine do at least.

The idle mixture screw is a brass knurled screw underneath the carb body set in with the bowl. You can't see them in your pictures. In for lean, out for rich. Blip the throttle after each half turn.

But if you're going to start adjusting the IMS I'd first verify that they are, in fact, 1.5 turns out by counting the number of turns it takes to LIGHTLY seat them.


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1978 Honda CB550K

[b5rider]

Thanks they do have a 'PD' stamped on them

[b5rider]

So the first thing to do would be a carb synchronization, and then mess with the adjustments. Thanks

[b5rider]

Cool. Thanks.might save me couple of hundred people charge to fix carbs

[b5rider]

Weird, I think they normally have the model number stamped on the side right under the PD...mine do at least.

The idle mixture screw is a brass knurled screw underneath the carb body set in with the bowl. You can't see them in your pictures. In for lean, out for rich. Blip the throttle after each half turn.

But if you're going to start adjusting the IMS I'd first verify that they are, in fact, 1.5 turns out by counting the number of turns it takes to LIGHTLY seat them.

I saw them. There are four; one for each carb, and they are knurled like you stated
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1978 Honda CB550K

[ANDY W]

that nut actually looks like a bolt, the stud must have been removed. i would agree with calj, they need to be vacuumed synced first then tuned. i suggest u read as much info on these carbs as possible,  check out the FAQ section for the 550. if u had the stock intake and exhaust then u could just set it to the factory settings but u don,t so u will have to tune to ur intake and exhaust setup. i know it may sound hard but once u familiarize urself with the parts and procedures it will be easier. 

[b5rider]

My 75 550 has the screws on the intake plenums, but the '78 does not. Can anyone tell me where I would attach the vacuum hoses to?

[DaveBarbier]

My 75 550 has the screws on the intake plenums, but the '78 does not. Can anyone tell me where I would attach the vacuum hoses to?

You can see the vacuum sync screws in your second picture. It's a screw right to the right of where it says KeiHin. It a small flat head screw angled upwards. There is one for each carb obviously.

Regarding that bolt that looks not tightened all the way. It's not for the intake plenum. It's the cam tensioner bolt. You can see it clearly in this shot. Still should be tight if it's not. Don't want that thing rattling around in there.




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1978 Honda CB550K

[b5rider]

OOOH, OK. Thanks
anyone know the size of the screws/adapters I might need?
Also, where would I find the air mixture adjustment screw on these PD carbs?

thanks!