Author Topic: RUNNING RICH WITH PODS?!  (Read 10236 times)

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Offline MattyK

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RUNNING RICH WITH PODS?!
« on: June 09, 2013, 02:15:28 PM »
Im putting the final touches on my cb550 and it runs and drives well except for the fact that it runs rich. The confusing part about this is that im running pods and you would expect it to run lean, no? However my plugs are black and exhaust smells a little rich, stock exhaust by the way. Also my cam chain is making a bit of noise, not sure if that applies to this or not but thought i would mention it. So whats going on here?
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Offline Randy

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Re: RUNNING RICH WITH PODS?!
« Reply #1 on: June 09, 2013, 02:20:03 PM »
re-sync the carbs what mains are you using?..
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Offline MattyK

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Re: RUNNING RICH WITH PODS?!
« Reply #2 on: June 09, 2013, 02:21:14 PM »
Sorry forgot to mention, jet sizes are stock as of now...
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Offline flybox1

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Re: RUNNING RICH WITH PODS?!
« Reply #3 on: June 09, 2013, 02:30:10 PM »
What do you consider stock?
'78 750K (F3 engine) PD42b's, Modified airbox w/K&N  filter, 40/110 jets, 1 needle shim, IMS@ 1 turn out. Kerker + Cone 18" QuietCore

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Offline MattyK

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Re: RUNNING RICH WITH PODS?!
« Reply #4 on: June 09, 2013, 02:37:34 PM »
Main: 100
Slow: 38
Right?
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Offline TwoTired

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Re: RUNNING RICH WITH PODS?!
« Reply #5 on: June 09, 2013, 03:29:59 PM »
What pods?  (over-oiled?)
What carbs?
What is the carb bowl fuel level?
Are the emulsion tubes clean?
What slide needle position?
Have the jets been drilled so that the markings lie?
Are the internal parts Keihin or aftermarket?


Any chance you are using the choke backwards?  (It's happened.)
Lloyd... (SOHC4 #11 Original Mail List)
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Offline MattyK

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Re: RUNNING RICH WITH PODS?!
« Reply #6 on: June 09, 2013, 05:03:13 PM »
All carb setting are stock, stock keihin carbs and cleaned and operating well. I guess I don't know if the jets are drilled but they don't look to be, haven't touched needle, idle screw is 3/4 turn out.
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Offline MattyK

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Re: RUNNING RICH WITH PODS?!
« Reply #7 on: June 09, 2013, 05:07:02 PM »
Pods:
 http://www.dimecitycycles.com/vintage-cafe-racer-caferacer-bobber-brat-chopper-custom-motorcycle-carburetor-intake-parts-39mm-k-and-n-pod-airfilter-12-55745.html

They are unoiled and I checked for anything stupid like paper inserts inside them, no obstructions.

Also I drive with the choke lever down, making the butterflies open.
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Offline andrewk

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Re: RUNNING RICH WITH PODS?!
« Reply #8 on: June 09, 2013, 05:16:43 PM »
How's it run when you ride?  Any flat spots or areas where the mixture is causing misfires?  By run and ride well, you mean that it'll pull 80mph without an issue, right?

Sort of related- how do you ride and what kind of conditions?  Do you use a decent cruising RPM (~4k and above), or are you lugging it around? Town, highway, mixed, etc.

Lastly, I find that the mid four is very sensitive to float level adjustments.  Are you sure they're adjusted properly?

Sorry to do nothing but ask questions, hope this leads to something helpful for you.


Offline MattyK

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Re: RUNNING RICH WITH PODS?!
« Reply #9 on: June 09, 2013, 05:30:34 PM »
No flat spots as far as I can tell, and it gets up to 80 pretty quickly without a problem. As far as how I ride, 90% of the time I'm above 4k. Floats are good, even and set to Honda specs, no leaks either...
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Offline Rodger

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Re: RUNNING RICH WITH PODS?!
« Reply #10 on: June 09, 2013, 06:16:29 PM »
I don't know much about tuning SOHC bikes.  But with twins like the CB350 many of the pods are more restrictive than stock air filters which cause this rich condition.  I know of someone running open headers with uni filters and his twin runs a little rich, I've found most pods do not move air as freely as you would like.  Trust the plugs
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Offline Xnavylfr

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Re: RUNNING RICH WITH PODS?!
« Reply #11 on: June 09, 2013, 08:19:47 PM »
ON most of the 4s ,running pods allows almost TOO much air and lots of time they are very hard to get the carbs tuned with PODS. You either have to restrict the airflow or go way BIG on main jets!!


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Offline matt mattison

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Re: RUNNING RICH WITH PODS?!
« Reply #12 on: June 10, 2013, 02:27:29 AM »
Maybe your oil fouling?
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Offline Lostboy Steve

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Re: RUNNING RICH WITH PODS?!
« Reply #13 on: June 10, 2013, 05:12:57 AM »
From what I understand (and I could be completely wrong) with pods there is less air at idle being funneled in. Think about how 4 cylinders are pulling air into a plenum, now remove that plenum and you have each cylinder pulling its own amount of air. With the throttle wide open that means more air flow, however at idle there is actually less "available" air. Dont know if that helps.
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Offline Xnavylfr

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Re: RUNNING RICH WITH PODS?!
« Reply #14 on: June 10, 2013, 05:54:05 AM »
You may be correct about less air flow at idle. But who does a PLUG CHOP at IDLE, or rides their bike at idle???


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Offline stickman

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Re: RUNNING RICH WITH PODS?!
« Reply #15 on: June 10, 2013, 06:28:23 AM »
Mattie,  I agree on checking your main jets.  Could be drilled.  I suggest you replace the mains and replace the plugs.  Pull a bowl, if overfilled recheck your float setting.  Try running it without the pods.
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Offline iron_worker

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Re: RUNNING RICH WITH PODS?!
« Reply #16 on: June 10, 2013, 07:23:54 AM »
You don't need to do plug chops at idle. You just have to listen to how the bike responds to "snapping" the throttle open. You should be able to snap the the throttle open up to half way and have the bike cleanly respond and rev out. Keep turning your idle screws out a bit at a time and testing to see how your thorttle response changes.

Note: The non-PD carbs (no accel pump) need to be over-rich at idle in order to be able to respond to quick changes of throttle position.

IW

Offline Lostboy Steve

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Re: RUNNING RICH WITH PODS?!
« Reply #17 on: June 10, 2013, 08:16:06 AM »
You may be correct about less air flow at idle. But who does a PLUG CHOP at IDLE, or rides their bike at idle???


Xnavylfr(CHUCK)

i hear ya, however if its grossly rich at idle it may carry over.
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Offline Xnavylfr

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Re: RUNNING RICH WITH PODS?!
« Reply #18 on: June 10, 2013, 04:03:27 PM »
If he has a # 40 IDLE jet and just say a #130 main jet. Your idle circuit  is where you draw fuel from at IDLE up to about 1/4 throttle then your MAIN jet starts feeding the carbs. I've seen many 750s with a perfect IDLE but when you crank the throttle open it just dumps fuel in and not enough AIR for it to burn = RICH.
Start with a # 40 slow/idle jet and about a 115/120 MAIN.
 You can't start correcting a problem without a baseline. Keep track of what you change and how it affected the bike.
IF you have STOCK then it should be #40 and #105.
Does it just BOG when you try to give it throttle?? the problem with pods is not so much the air volume but the air flow..  a STOCK air box is shaped in a way to cause the air to vortex and cause LOW pressure in the carb throat which in turn causes vacuum. A velocity stack open works BETTER than the pods because they cause the air to be pulled directly in to the carb throat, the air through pods have to flow from the side of the carb to get in the throats.  You want really find out about PODS, get the bike running decent with them and ride with your legs tucked in against the tank ,then spread your legs out in the airflow and see how the bike acts .

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Offline TwoTired

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Re: RUNNING RICH WITH PODS?!
« Reply #19 on: June 10, 2013, 05:31:56 PM »
I still don't know which carb style the OP has even though I asked about that as well as other things that were ignored.

But, in case someone else reads this and gets a misunderstanding about how the 550 carbs work.  I'm going to correct/refine some of the things posted.

If he has a # 40 IDLE jet and just say a #130 main jet. Your idle circuit  is where you draw fuel from at IDLE up to about 1/4 throttle then your MAIN jet starts feeding the carbs.
I prefer to use "pilot circuit" for these carbs, as they have no shut off mechanism linked to slide position, or RPM.  The circuit forms the "base line" fuel mixture when the slides are at or near closure.  As mentioned, mechanical slide carbs that have no accelerator pump do need an over rich pilot mixture to get the RPMs up when the slides are lifted.

I've seen many 750s with a perfect IDLE but when you crank the throttle open it just dumps fuel in and not enough AIR for it to burn = RICH.

I don't see how this is possible without an accelerator pump.  When the slides lift, the carb throat vacuum immediately moves toward Outside Atmospheric Pressure (OAP).  OAP is what pushes all the fuel through any of the fuel metering jets when and only when the carb throat pressure is less than OAP.    Thus, fuel metering volume diminishes when the slides are raised, and less fuel or a leaner mixture is a result.  If the pilot mix is over-rich enough to allow RPM increases, the eventual velocity increase causes the venturi effect to lower the throat vacuum and fuel delivery ratios can then be restored.

PODS shorten the entire inlet duct and bring OAP much closer to the carb throat fuel jet delivery points, resulting in less available pressure differential, and less fuel volume drawn through existing jet orifices.  To restore the volume of fuel drawn up from the bowl with these lower pressures, the orifice size is increased.  For the early carb pilot screws, you can reduce the amount of air introduced to the pilot circuit, which has the effect of mixture enrichment.  IDLE Mixture Screws (IMS), found on the PD style carbs, regulate the total volume of  the fuel air mix from the pilot circuit.  Depending on the pressure drop characteristics of the filter membrane, the pilot air screws or IMS may or may not have enough range of adjustment to restore the off idle response under load.

Does it just BOG when you try to give it throttle?? the problem with pods is not so much the air volume but the air flow..
Particularly at idle speeds, the air volume or flow is unchanged between pods and the stock induction.  Such volume or flow is determined by the volumetric efficiency of the cylinder, which is unchanged with an induction mod.  There may be differences in volume or flow up near red line RPM, though.

a STOCK air box is shaped in a way to cause the air to vortex and cause LOW pressure in the carb throat which in turn causes vacuum.

A velocity stack open works BETTER than the pods because they cause the air to be pulled directly in to the carb throat, the air through pods have to flow from the side of the carb to get in the throats.  You want really find out about PODS, get the bike running decent with them and ride with your legs tucked in against the tank ,then spread your legs out in the airflow and see how the bike acts .
You may wish to review your theory of operation about this.  I won't pick it to pieces here.  I'll just say it appears very "creative".

There is really only one driving force causing fuel to pass from carb bowl to carb throat, and that is air pressure differential.  Differential pressure comes from two sources, the falling piston on the intake stroke, and venturi effect when there is enough velocity to produce a pressure drop from forcing an air speed increase through a restriction.

I will say that while the main jet does supply the throttle valve (Slide needle), the main jet performs no restriction on fuel mixture until the slide needles have been raised to the 3/4 or more position.  Mixtures below these throttle positions, are restriction metered by the throttle valve diameter and taper, variable with slide position.

There are, of course many other tuning details within the carbs, but the ones mentioned are the major ones who's concepts should be firmly grasped first.  Discussion of those is more appropriate when it is known which model carb is being discussed.

Lloyd... (SOHC4 #11 Original Mail List)
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Offline MattyK

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Re: RUNNING RICH WITH PODS?!
« Reply #20 on: June 10, 2013, 09:05:10 PM »
Sorry everyone,  I have been really busy and haven;t had a chance to log on. Ill address some of the stuff questioned. I put a link up to the exact pods I have in an earlier post on this thread. Second, I have the stock Keihin carbs for a 1974 cb550k. Third, throttle responsiveness was very good, it pulled hard and smooth, its just that it ran rich and made cam chain noise.

HOWEVER, today a major malfunction occurred. I was driving around the block trying to observe some of the stuff that you guys have suggested, but today was very different than other days. It was lurky and lungy at open throttle, was popping and crackling, and running hot. I ran it for about 10 minutes around the block and before i got back home it sputtered and died. Everything electrical is okay, it cranks and everything. but it wont run now, cant get it to idle. Im not out of gas and gas is getting to the carbs, so im not sure what to do now...im going to pull the carbs soon and check it out as i have to see if i can adjust the cam chain anyway. Any tips or ideas as to what caused this?
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Offline TwoTired

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Re: RUNNING RICH WITH PODS?!
« Reply #21 on: June 10, 2013, 10:19:27 PM »
If it is running as rich as you say, the spark plugs may be fouled with soot.  This will short out the spark plug tips and shunt all the spark energy away from the spark gap.

Are the plugs D7EA?

Look at the spark plug deposits.
Compare them to:
http://www.dansmc.com/Spark_Plugs/Spark_Plugs_catalog.html
 Tell what you have or post pictures of them.

Or, maybe your battery has simply run down due to too much low RPM operation.  Check the voltage.  Recharge if necessary.

Stock coils and points?

Lloyd... (SOHC4 #11 Original Mail List)
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Offline PeWe

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Re: RUNNING RICH WITH PODS?!
« Reply #22 on: June 11, 2013, 03:18:59 AM »
About spark plugs.... I have never had a problem with NGK D8EA and similar NGK when it is a CB750. Bosch silver and Nippondenso (CB750 recommended models) however, did all stop work after a few minutes one by one, completely black.
Maybe I had too rich mixture on low throttle lift, but NGK did not mind and I did not change the mixture at that time when I saw this as a spark plug problem.
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Offline MattyK

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Re: RUNNING RICH WITH PODS?!
« Reply #23 on: June 11, 2013, 01:25:28 PM »
Good news is it started up today after a minute or two of cranking, but I pulled the plug and took a picture, ngk d7ea's and I'm assuming its number 3 on that list, carbon fouled. Also do you have any tips on getting cylinder two and three plugs out? My ratchet set is too big, just wondering if there's a way around it without having to buy a new set. What do you guys recommend? Pull the plugs and buy news ones and see how it runs without the pods?
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Offline MattyK

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Re: RUNNING RICH WITH PODS?!
« Reply #24 on: June 11, 2013, 01:33:26 PM »
Also, stock coils and points, voltage is near perfect. I forgot to mention that I took the pods off to run it today and i noticed little puffs of gas coming out each intake inlet on the carbs. Is this normal or am I just being completely stupid here?
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