Topic: Yes another pods question

[mach62468]

Recently I have installed pods and bumped my main jets up to 115's. I also have open exhaust. The problem is that at start up I have alittle backfire thru the exhaust until it warms up then I am getting some decell pop thru the carbs at low speed also. I was wandering if this was caused by the pods or a if I just need to adjust timing since I installed the pods? or maybe there is something els I haven't thought of.Thanks in advance.

[ekpent]

I'll be the first. What bike for starters and make sure that the timing is set properly to spec.

[mach62468]

Sorry its a cb550 and the timing was fine before I changed to pods so I wouldn't have thought it would have changed but wasn't sure with the change in flow if it would affect the correct timing placement.

[BobbyR]

There are several Pods threads that goes into great detail about how people set those up successfully. I suggest you do a search, you will get a lot of good info quickly.

[TwoTired]

You just changed to pods and didn't bother with the rest of the 3000 mile tune up check list?

Anyway, you aren't getting more flow with pods (except perhaps above 9000 RPM), you just changed the duct length and the internal pressures in the carb throat.  It's those pressures which determine draw from the jets.  Raise the pressure toward outside atmospheric, (shorter duct length, lower membrane pressure differential) and less fuel flows from the stock jets sizes.  To compensate, you need larger orifices to flow the same fuel volume as with the stock jets and higher differential pressures.

[grcamna2]

I am very familiar & really enjoy sealed & full exhaust systems w/ mufflers...that said,I only had popping on decelleration when I had air leaks in the exhaust systems,like they weren't sealed any longer.

[mach62468]

Two Tired, I did a complete tune up cleaning and adjusting points, adjusting valve tappets and everything else. I also wrapped the exhaust and changed exhaust gaskets while I was at it. So I still need to know if I need to change the timing to correct my problems or if there is something else I have overlooked.

[Retro Rocket]

Two Tired, I did a complete tune up cleaning and adjusting points, adjusting valve tappets and everything else. I also wrapped the exhaust and changed exhaust gaskets while I was at it. So I still need to know if I need to change the timing to correct my problems or if there is something else I have overlooked.

Popping on decel and poor of idle running are both symptoms of pods.
What TT is trying to say is that most  pods are crap and your bike will never run as well with pods on it, period....
I won't bother saying any more because there are plenty of threads that discuss this in great depth on this forum and i am so over repeating myself almost on a weekly basis........

[TwoTired]

Seems unlikely timing is going to fix/effect your reported symptoms (which are indicative of lean mixtures).

What setting are your pilot air bleed screws?  And, what needle clip position for the throttle valve?
What happens if you are in top gear at 2000RPM and you suddenly open the throttle to 50% of total travel?

To compensate for pods and reduced exhaust pressure, you need to make more carb changes than just the main jet size.
You may need to vacuum sync your carbs, as well. (If you haven't already).

[BobbyR]

Mach, what everyone is telling you in a polite way us that Pods need a lot of tweaking, much more than people either want to do or have the ability to do. They are not bolt on accessories like a luggage rack.

[crazypj]

If airbox rubbers are good, re-fit stock airbox.
 Depending on the model of 550, it's going to be frustrating to near impossible to get running right.
 I've posted in several threads about 550/pods jetting, you'll have to search out the 550 jetting threads
If you have plenty of carb experience, carry on

[mach62468]

Mach, what everyone is telling you in a polite way us that Pods need a lot of tweaking, much more than people either want to do or have the ability to do. They are not bolt on accessories like a luggage rack.

Thank you I figured it would be tough but I have alittle mechanical experience but mostly with cars and trucks(A.S.E. Master certified) This is the first time I have messed with more than 2 carbs. It seems like this is this place to ask if I want to find out.

[mach62468]

Seems unlikely timing is going to fix/effect your reported symptoms (which are indicative of lean mixtures).

What setting are your pilot air bleed screws?  And, what needle clip position for the throttle valve?
What happens if you are in top gear at 2000RPM and you suddenly open the throttle to 50% of total travel?

To compensate for pods and reduced exhaust pressure, you need to make more carb changes than just the main jet size.
You may need to vacuum sync your carbs, as well. (If you haven't already).

I.m looking for a sychro now, The pilot and throttle valve are still in standard position I guess since I haven't moved them and as far as the top gear at 2000 I'll have to try 2maro. I know it seems to have around the same amount of power as it had before(just a little less). I'll try to get in the shop and check the specifics 2maro and let you kno TT Thanks alot.

[mach62468]

Seems unlikely timing is going to fix/effect your reported symptoms (which are indicative of lean mixtures).

What setting are your pilot air bleed screws?  And, what needle clip position for the throttle valve?
What happens if you are in top gear at 2000RPM and you suddenly open the throttle to 50% of total travel?

To compensate for pods and reduced exhaust pressure, you need to make more carb changes than just the main jet size.
You may need to vacuum sync your carbs, as well. (If you haven't already).

I.m looking for a sychro now, The pilot and throttle valve are still in standard position I guess since I haven't moved them and as far as the top gear at 2000 I'll have to try 2maro. I know it seems to have around the same amount of power as it had before(just a little less). I'll try to get in the shop and check the specifics 2maro and let you kno TT Thanks alot.

Ok TT pilots are at 2 turns and at 2000 and 5th gear half throttle it spits for a second then takes right off and as far as the throttle valve setting I still am unsure I won't have time to take it apart til this weekend to be sure.

[TwoTired]

Turn the pilot air bleeds inward 1/2 turn, and repeat the throttle test.
If there is still stumble then go inward another 1/4 turn, test again.

Don't expect to whack the throttle full open.  You would need accelerator pumps for that to work right.  Don't turn the air screws inward til you can whack to full throttle and go, because then the idle mixture will be too rich and the spark plugs will gain soot deposits while idling.
What you want is to turn the screws inward just enough to get that 1/2 twist throttle response under load.

I'll warn you that you may have gone too big on the main.  And, every time you change one metering path, you will have to revisit the other two.

Lots of people just tinker until it seems "good enough", and live with the remaining faults, or sell the bike to someone else.

With those big jets, expect fuel mileage to be awful, with a lot of unburned hydrocarbons getting dumped out the exhaust.

[mach62468]

Turn the pilot air bleeds inward 1/2 turn, and repeat the throttle test.
If there is still stumble then go inward another 1/4 turn, test again.

Don't expect to whack the throttle full open.  You would need accelerator pumps for that to work right.  Don't turn the air screws inward til you can whack to full throttle and go, because then the idle mixture will be too rich and the spark plugs will gain soot deposits while idling.
What you want is to turn the screws inward just enough to get that 1/2 twist throttle response under load.

I'll warn you that you may have gone too big on the main.  And, every time you change one metering path, you will have to revisit the other two.

Lots of people just tinker until it seems "good enough", and live with the remaining faults, or sell the bike to someone else.

With those big jets, expect fuel mileage to be awful, with a lot of unburned hydrocarbons getting dumped out the exhaust.

Alright i'll try that thanks for your help. What size main should I have gone with?

[Randy]

my 500-4 runs on 105 mains...Slide setting in the last one.. I can't whack the throttle from a stand still or it will bog down.. Be halls on the top end. around 5 to 7k

[TwoTired]

I'm just guessing.  "Pods" is not a specification, it's a style.  Their functional characteristics can vary among manufacturers, which would directly effect the carb throat vacuum levels and fuel flow from metering jets.  Notice pods are often cheap.  So, there is not a lot of engineering effort or expense put into them at the product level.  Unfortunately, just because some are more expensive doesn't necessarily mean they are superior.  They may simply be priced at what the market will bear (like gas/oil, music, and hamburgers).

If I put my soothsayer hat on  , I'd guess something like 107/110 mains, and raise the slide needles another notch. Then re-tune the pilot screws for correct throttle response.  But, that's just a W.A.G.

Reading the spark plug deposits would give better indications/data on which to base a decision.  Even better would be to put the machine on a dyno, and get a fuel map. That would tell you just what it's needs are and what metering device needs to be changed/adjusted.  But, unless you've changed something in the engine mechanicals to enhance breathing capacity, it probably still won't run as well as stock.  But, you'll still get from point A to point B.

Cheers,

[edbikerii]

Alright i'll try that thanks for your help. What size main should I have gone with?

Try 105s.  1977-78 550 carbs are different from earlier models, but my 77 ran beautifully with 105s.  See the threads in my signature for TONS of information on jetting 550s, 1977-1978 in particular.

Have fun.

[phil71]

the big thing those cheap pods do is eliminate the toy velocity stacks the stock airbox has. That little bit of restriction goes a long way towards it running right.
Good luck .. you're gonna be amazing at taking carbs off, and apart quickly before very long.

[Danno]

the 550 will never run right on pods as retro has already said  and I agree the carbs are not made for turbulent air they run like #$%* that way and you must have some back pressure or risk burning a valve .......yada yada yada we have all tried to help people understand this about the 550 but if you are so stubborn that you have to have them then pick up some CV carbs off a 650 four and use those it will run half right but you need some back pressure also  straight pipes won't work either

[crazypj]

the 550 will never run right on pods as retro has already said  and I agree

 My 77 550 ran fine for about 70,000 miles, BUT, I spend a LOT of time getting carburation right (I've posted it multiple times, not going to repeat again)
 If you have access to dyno with EGA, setting up should be pretty simple.
 Unless you have experience of SU carbs, variable venturi are nothing like fixed venturi automotive carbs

[MCRider]

All this talk of pods and air filters brings back something from many moons ago. We used to call the stock air box a "still air box". I haven't read or heard anyone call it that in ... decades. (Maybe I've missed it here).

Of course there were comments that the purpose of the box was to calm the air flow before going into the carb. And that if you removed that stillness you were asking for erratic behavior.

So I thought I would throw that tidbit in the mix, on the side of the still air box crowd.

On the other hand, I've used pods quite successfully, but on a larger bore CB750 with different carburetors, so its really not apples to apples. It may be that the different carbs, which won't nestle up to the stock still air box anyway, do all right with pods.

And there are other models like my HawkGT where the still air box is a major limiting factor to performance. And pods, with a DynaJet kit, is an easy fix. Dyno proven. Except they are much louder.

So there is no blanket answer across the spectrum. There may be a blanket answer for CB500/550s with stock carbs. 

[BobbyR]

The"still air box" is probably a good description. If you notice it draws the air from the rear of the box. Honda may have done air flow studies and found quiet air in that spot. I remember reading about why considering the weight why bikes don;t get higher gas mileage. It seems that air just bounces around the frame and just around everything bolted to the frame.  Very little quiet air while you are moving.

Honda probably  could have slapped POds on the bike, which would have been cheaper and easier than the airbox.

[TwoTired]

Just a point of clarification.  In a running bike, there is no still air in the induction system.  There can be and is desirable to have laminar flow air.

Anytime air has to hit or go around an obstruction in its path, the flow becomes non-laminar or turbulent.  This could be a flag pole, wall, or strands of filter fiber.  Turbulent air can convert back to laminar flow if given a plenum area to collect and lose their turbulent energy.

There is a filter inlet edge, and a filter membrane and both can cause the air to turbulate.  Turbulent air can cause a restrictive condition as some of the air is actually flowing in a direction that is not toward the carb.  It takes some energy change to divert it's path.
Anyway, after the air filter turbulence, a plenum allows the air being siphoned off toward the inlet funnels for the carbs, to return to a laminar flow condition.
 Pod filters are far too close to the carb inlets to truly return the airflow back to laminar, except at very high air velocities and/or high pressure differentials.  So, it may not be much concern at or above red line RPMs.  But, it almost certainly will present modal pressure differentials at the fuel jet exits, while using street speeds.  And that, will make the mixture settings unpredictable in those operating regimes where a thousand RPM difference can mean going from lean to rich and vice versa.   You can find compromises, if you work the issue long enough, though.  After all, you can get the mixture to fire at ratios between 5:1 and 20:1.  But, those extreme ratios are not efficient, or conducive to maximum power output.
Still, many live with that happily, as they wail on the throttle at 90% position.

Cheers,