Topic: Pods Thread

[hapsh]

I also find it interesting that if you look through the older threads on this topic that you will find a few of the POD people actually tried the stock airbox and really enjoyed the stronger low end power, but still went back to pods.  I have run pods on my bikes for almost 30 years because 1) I didn't know the stock airbox offered any benefit 2) It was difficult to acquire a stock airbox since my bikes were all stripped of them before I got them.  But once I tried out the stock airbox I was absolutely amazed at how much the overall performance and MPG improved.  Even if pods are found to improve power at WOT and high RPM, what good is it on the street with a 30+ year old bike.  These engines aren't getting any younger so constantly thrashing them at the redline to access that power doesn't sound like a good idea.  I prefer to have good usable power across the throttle and RPM band for 98% of the riding I do.  And for those times I thrash it at the redline I am sure I wont even care about any 5 hp gain I might get from pods.  My 550 will never come remotely close to the power of my FZR600 or R6 even though they have practically the same engine size.  So I just try to enjoy my 550 for what it is worth; unique looking bike with decent power, and a vastly different exhaust note when compared to modern bikes.
One other note is that back in the 80s when they made stock airboxes optional on the AMA Superbike class they found that they had better lap times with the airbox so many riders opted to keep the airbox.
On the other hand, if you are making your SOHC Honda into a cafe, it is hard to beat the look of pods or velocity stacks.  The stock airbox looks pretty ugly.  So you have to decide what is more important.  I found a compromise however.  I modified some vintage oval number plates to hide my stock airbox so I still have the performance I want and still have the look of a vintage racer.

[TwoTired]

Perhaps we should argue about whether or not we should argue?

I suppose I don't care if people want to keep or use pods.  I feel we have a right to name our own poison, or toss one's own bike off a cliff if that is their passion.  My concern is the folklore that makes the assumption pods automatically gain the engine more power (on a no-factual basis).  And, any newbie that comes along is automatically persuaded to dump the "crappy" airbox/filter for the "superior" pods, despite the skill and extra work required to make them function as well as the stock setup.  I'd like to stop the lies, so to speak.

In my mind, pods should only be employed by people that also have available a dyno, or a test track and 10-40 hours of fine tuning time commitment.  I'd like a realization that pods aren't just for looks, they actually effect the vehicle performance (not always in a good way) and that simply making the jets 10 times bigger isn't a cure-all or cheap horsepower gainer.

I'd also like to see the converters save the stock air box setup, so when they sell the bike to unsuspecting buyers, the buyer has some hope of getting the bike to perform properly once again. 

But, there is no need to tell me that the world isn't perfect.

.....IMHO, of course.

[scondon]

 Very good points, TT. And this from a daily pod user        It hurts to see someone with a new ,to them, SOHC riding with pods on a stock bike. Most of the time I see this I also see signs of the engine running too hot in some throttle ranges, pipes bluing and gasket leaks starting up, etc...   It really does take a bit of carb fiddling to get the burn decent through the throttle range and even then I believe that the stock box is a better choice for overall performance.

     The air opening in the bottom of my '78 airbox just wasn't enough for my first 836 engine at 8500+ rpm's so I used pods. Lots of fiddling with the idle mixture to get it running decent at idle but still had to run a tad rich to keep engine going at 1200rpm or less until very hot. Constant raising and lowering of needles while trying to find the perfect main jet etc...

    I reinstalled the stock box with a K&N single filter and drilled some holes in the back of it and the carbs were much easier to tune, had good pull throughout the throttle range and all that I needed at WOT.

    If I could use the drilled  'box with the CR Specials I'd certainly give it a go

[BobbyR]

Lloyd, I am a professional trainer. All I can do is give people the facts and recommended procedures as you have done. I know they will do what they believe or what they feel like doing when I am gone. That is all we can do.

[mlinder]

That's mighty white of ya. Good to know that your profession precludes the idea that, yes, performance can be increased in these old engines. Guess MRieks, hondamans, paulages, et al, efforts are all for naught.

Again, I'm not saying pods help a cb 750 gain performance by themselves (though, I should go test between velocity stacks and stock airbox...), but if the engine can use more air and fuel that a stock airbox can feed it, derestricing where you can will help top end performance.

[BobbyR]

That's mighty white of ya. Good to know that your profession precludes the idea that, yes, performance can be increased in these old engines. Guess MRieks, hondamans, paulages, et al, efforts are all for naught.

Again, I'm not saying pods help a cb 750 gain performance by themselves (though, I should go test between velocity stacks and stock airbox...), but if the engine can use more air and fuel that a stock airbox can feed it, derestricing where you can will help top end performance.

Look up ponderous in the dictionary. What Mike and Hondaman and the others are doing are making tried and true improvements and modifications. Your lack of understanding of what they are doing is an insult to them. They are not just sticking some "things" on the engine.

[mlinder]

That's mighty white of ya. Good to know that your profession precludes the idea that, yes, performance can be increased in these old engines. Guess MRieks, hondamans, paulages, et al, efforts are all for naught.

Again, I'm not saying pods help a cb 750 gain performance by themselves (though, I should go test between velocity stacks and stock airbox...), but if the engine can use more air and fuel that a stock airbox can feed it, derestricing where you can will help top end performance.

Look up ponderous in the dictionary. What Mike and Hondaman and the others are doing are making tried and true improvements and modifications. Your lack of understanding of what they are doing is an insult to them. They are not just sticking some "things" on the engine.

You haven't read my posts, and your presumption that I don't understand what constitutes (and what is required for) increased engine performance is pretty unfounded.
Again, I do not assume that pods increase performance in the application we are talking about: namely, stock, SOHC4 hondas. I don't think they do.
But I daresay I probably understand the theories better than most (though, far less than the aforementioned gurus).

Your methods of arguing points are quite.. interesting...

But I notice you haven't actually addressed any real points I've made. Namely,

If an engine can use more fuel and air than a stock intake system can deliver, removing restriction can increase performance.

Now, argue against that point, instead of arguing about something else and trying to make it apply to the above statement.


(p.s. I don't need a dictionary for extremely common words, but thanks anyway.)

[TwoTired]

If an engine can use more fuel and air than a stock intake system can deliver, removing restriction can increase performance.

What metrics will you use to determine if more fuel and/or air is being "delivered" and how will you measure "performance"?

[mlinder]

If an engine can use more fuel and air than a stock intake system can deliver, removing restriction can increase performance.

What metrics will you use to determine if more fuel and/or air is being "delivered" and how will you measure "performance"?

Thanks Lloyd, a reasonable and well thought out question.

I'll tell you what. I don't have a flow bench or other equipment needed to measure the volume of air and fuel delivered.
But, when my cb350t (head by mrieck, thanks mike) racebike is done, I'm going to have to go to the dyno to jet it.
We'll see if it makes more power than a stock cb350t, eh? Is that a good enough performance measurement? It's not a sohc4, and other things are done to it, but I can guarantee that stock carbs and stock intake would not be able to deliver what the engine will need.

/edit: Now that I think about it, I suppose I could put the stock carbs and airbox on the cb350 after the work is done, and dyno that too. That woul dhelp prove the point that "If an engine can use more fuel and air than a stock intake system can deliver, removing restriction can increase performance.", though I thought the statement would be pretty self evident.

[edbikerii]

Hi hapsh. 

Yes, I initially went back to my stock airbox because I really could not be bothered to rejet my carbs properly for the pods at that time.  Of course the bike ran better, since I had been running pods and aftermarket exhaust without re-jetting.  I experienced no low-end power increase with the stock airbox.  It just had almost the right mixture with stock airbox and jets, so it didn't sputter and bog out.  Now that I've invested the time and energy to re-jet properly, my bike runs well throughout the RPM range.

If you installed the airbox and the bike ran better, then I can assure you that the carbs had not been jetted properly for pods.

I don't own my bike so it can sit in a museum someday long after I'm dead and buried.  I ride my bike.  I ride it hard, rev it up high, and expect it to perform as well as my budget will allow.  If the engine blows up, I'll either rebuild it again or buy another bike.

I'm not a purist, but if you want to be one, go right ahead.  Just don't tell me what to do with my bike.

I also find it interesting that if you look through the older threads on this topic that you will find a few of the POD people actually tried the stock airbox and really enjoyed the stronger low end power, but still went back to pods.  I have run pods on my bikes for almost 30 years because 1) I didn't know the stock airbox offered any benefit 2) It was difficult to acquire a stock airbox since my bikes were all stripped of them before I got them.  But once I tried out the stock airbox I was absolutely amazed at how much the overall performance and MPG improved.  Even if pods are found to improve power at WOT and high RPM, what good is it on the street with a 30+ year old bike.  These engines aren't getting any younger so constantly thrashing them at the redline to access that power doesn't sound like a good idea.  I prefer to have good usable power across the throttle and RPM band for 98% of the riding I do.  And for those times I thrash it at the redline I am sure I wont even care about any 5 hp gain I might get from pods.  My 550 will never come remotely close to the power of my FZR600 or R6 even though they have practically the same engine size.  So I just try to enjoy my 550 for what it is worth; unique looking bike with decent power, and a vastly different exhaust note when compared to modern bikes.
One other note is that back in the 80s when they made stock airboxes optional on the AMA Superbike class they found that they had better lap times with the airbox so many riders opted to keep the airbox.
On the other hand, if you are making your SOHC Honda into a cafe, it is hard to beat the look of pods or velocity stacks.  The stock airbox looks pretty ugly.  So you have to decide what is more important.  I found a compromise however.  I modified some vintage oval number plates to hide my stock airbox so I still have the performance I want and still have the look of a vintage racer.

[paulages]

i definitely don't want to get in the middle of this, but this article (with flow-tested data): http://members.tripod.com/cb750k2/Technical/porting/Porting_the_Honda_Head.htm shows that the stock keihin carbs are restrictive at a certain point. Whether or not the stock filter and plenum as further hindering this is not described, but the testing does at least show that the stock head can benefit from better breathing (larger carbs) at .250 lift.

for the record, i have no side here. i'm honestly interested in the true answer to this debate. for the most part, i'm an airbox advocate. the real question remaining is whether decent pods actually do flow better or not.


here is an excerpt from the jerry branch article:

...[describing the test process] Air is pulled into the carburetor intake and through the port at varying degrees of valve lift to check the capabilities of the port at any point in the cycle.
The first bit of information gained from the stock configuration test was that the Honda 750 head reaches maximum flow at a valve lift of only .250. At the .250 lift point, air flow has risen from zero to 54.8-CFM (cubic feet per minute). Going all the way to .450 lift only increased the flow to 58.7-CFM, indicating that the stock Honda Four engine requires a cam with a long duration, which will open the valve quickly and hold it open at moderate lift (about .300-inches) for an extended period of time to allow complete filling of the cylinder. High lift is not needed and cannot be used effectively until the port shape is improved to a point where the engine will flow much larger amounts of air at high lifts.

Using this radiused entry on the intake port gives a guide line reading to determine overall flow rate of the stock and modified ports. Finished port had 105.6 CFM frow rate!    Jerry also performed a test without the valve installed, but retained the stock 28mm Keihin carburetor. The airflow increased a very small amount to 60.3-CFM demonstrating that the design of the valve is very good just the way it is and presents no large restriction to airflow. The final test on the stock head consisted of removing both the valve and the carburetion and adapting a venturi to the intake port to see how much air could be pulled through the port under ideal conditions. The test, called an "entry only" test, gave a figure of 77.3-CFM indicating that while the valve does not present much restriction to airflow, the stock Keihin carburetor does.

Jerry decided to adapt a larger carburetor to the stock head and chose a 32mm Mikuni. The Mikuni is a better flowing carb and is still small enough that four of these 32mm units will fit the engine and frame without much modification. The test showed- that the Mikuni installation was good for an increase of 5.9-CFM at the .250 lift point and would allow a further increase in flow to 65.7-CFM at .350-inch lift before the curve started to flatten out again. This is a substantial improvement for a bolt-on part.

A further test with the valve removed and the 32mm Mikuni gave a reading of 71.7-CFM, not too far down from the entry-only figure of 77.3-CFM. Jerry feels that the 32mm Mikuni would be perfect for racing use, or on large displacement street engines. For a stock cubic-inch Honda Four the 30mm size would work best.

[mlinder]

I'd read that article a couple of times, too, Paul.
So yeah, as I said, I don't really think pods do much, if anything at all, beneficial.
Doesn't mean that increased air and fuel delivery (by whatever means make it possible) won't increase performance in an engine that is being starved of fuel and air by a restrictive intake.

[BobbyR]

That's mighty white of ya. Good to know that your profession precludes the idea that, yes, performance can be increased in these old engines. Guess MRieks, hondamans, paulages, et al, efforts are all for naught.

Again, I'm not saying pods help a cb 750 gain performance by themselves (though, I should go test between velocity stacks and stock airbox...), but if the engine can use more air and fuel that a stock airbox can feed it, derestricing where you can will help top end performance.

Look up ponderous in the dictionary. What Mike and Hondaman and the others are doing are making tried and true improvements and modifications. Your lack of understanding of what they are doing is an insult to them. They are not just sticking some "things" on the engine.

You haven't read my posts, and your presumption that I don't understand what constitutes (and what is required for) increased engine performance is pretty unfounded.
Again, I do not assume that pods increase performance in the application we are talking about: namely, stock, SOHC4 hondas. I don't think they do.
But I daresay I probably understand the theories better than most (though, far less than the aforementioned gurus).

Your methods of arguing points are quite.. interesting...

But I notice you haven't actually addressed any real points I've made. Namely,

If an engine can use more fuel and air than a stock intake system can deliver, removing restriction can increase performance.

Now, argue against that point, instead of arguing about something else and trying to make it apply to the above statement.


(p.s. I don't need a dictionary for extremely common words, but thanks anyway.)

The point is quite simple. Honda had engineers, very good engineers who understood and tested the flow of air through the system from the intake slot of the airbox to the tips of the 4-4 exhausts. They created a "system" that took into account reliability and rideability within a given RPM range to give you smooth performance within that range. Honda tweaked the SOHC engine and heads up until 1978 as they gained more knowledge via experience, some of it gained on the track and some gained on the bench. I am sure that during that process they had some ideas that on the surface looked like it would work and did not in practice.
Hondaman's ingintions are based on solid electronic theory, it is not a "spark intensifier from JC Whitney" It would have been impractical and expensive at that time to incorporate that ignition into a mass produced bike. So, they used points, tried and true points.
Mike's head work is a painstaking labor intensive process that likewise would have been impactical in a production environment. If you incorporate Mike's engine work with Hondaman's ingnitions, yes you could pass more air and fuel through the engine and get more power. Mike put his motor work through a Dyno test to prove to himself that he had gotten it right.
 
Modern inline Honda engines in the 650 to 750 class with carbs put out in excess of 100hp and they do not use PODS, they use an engineered air induction system designed for a specific outcome.

I teach people every week about maintaining and overhauling Railcar "systems" while they are good with tools and they repair things well, they many times do not really understand how the systems actually work. They most often do not understand how the various systems interact with the other systems. If you change one thing, you unbalance the system.

[mlinder]

And you seem to think that I'm not aware of everything you just said.

Which would be erroneous on your part.

Take a look at the link Paulages put up. Then tell me the stock intake system is not restrictive.
Am I claiming that pods are better? No.
I am claiming that it's entirely possible that derestricting the intake on a sohc4 would help make more power at the top of the rev range.
Not that it would make more power overall, or that pods are the way to do it (because I don't think they are).

Do you understand this?

(edit: Oh, yeah, you forgot to answer the question AGAIN... )

[edbikerii]

The article is entitled, "Even the best of things can stand some improvement...  Porting the Honda head"

That whole article is about improving upon the work that the Honda engineers did, in order to gain horsepower.  The article indicated that the carburetors can be improved and that the ports can be improved.  They made no mention of the airbox or pod filters whatsoever.

Don't forget other requirement from the EPA that influenced the design of the airbox like noise control, cold weather running, etc.  Have any of you guys experienced carb icing on cold, damp days?  Some of these issues are just not a concern for many of us.

[BobbyR]

And you seem to think that I'm not aware of everything you just said.

Which would be erroneous on your part.

Take a look at the link Paulages put up. Then tell me the stock intake system is not restrictive.
Am I claiming that pods are better? No.
I am claiming that it's entirely possible that derestricting the intake on a sohc4 would help make more power at the top of the rev range.
Not that it would make more power overall, or that pods are the way to do it (because I don't think they are).

Do you understand this?

(edit: Oh, yeah, you forgot to answer the question AGAIN... )

Yes I agreed "If you incorporate Mike's engine work with Hondaman's ingnitions, yes you could pass more air and fuel through the engine and get more power. Mike put his motor work through a Dyno test to prove to himself that he had gotten it right."

[mlinder]

No. Wrong answer.

If the stock intake system on a stock engine is restrictive at higher RPM's, then derestricting the intake can increase power up in those RPM's.

Doesn't have anything to do with aftermarket headwork.

Or do you deny this?

[BobbyR]

No. Wrong answer.

If the stock intake system on a stock engine is restrictive at higher RPM's, then derestricting the intake can increase power up in those RPM's.

Doesn't have anything to do with aftermarket headwork.

Or do you deny this?

Yesssssssssssssssssssssssssss, yesssssssssssssssssssssssssss, Yessssssssssssssssssssss, yessssssssssssssssssssssssss. How could I not have understood your point. Of course you are right. OMG what a revelation. Bless you, bless you, bless you. 

[mlinder]

Thank you.

Then it stands to reason, that, IF the sohc4's are indeed restricted at the top end of the rev range, and IF pods did, in fact, improve the amount of air that can be pulled through the engine at said RPMS (which I don't think they do), then pods would, in fact, increase top end performance.

Lots of 'ifs' there, I know.

Sorry to give you a seizure

[scondon]

   According to the article higher flow rates were measured by switching from 28mm to 32mm carburetors on a stock motor, yes? The carb throats are the restriction in this test assuming that no air filtration was used during the test, yes?

    Though the topic of the thread is "Pods v standard airbox" we are far from discussing anything related to air filtration at this point, yes? No "specific" points are being made or used (or harmed in any manner) in this debate, yes? Somewhere a scientist/engineer is weeping, yes?

 DING!   To your corners gentlemen

[mlinder]

 BEDEVERE:
    Exactly. So, logically...
VILLAGER #1:
    If... she... weighs... the same as a duck,... she's made of wood.
BEDEVERE:
    And therefore?
VILLAGER #2:
    A witch!

[Gordon]

BEDEVERE:
    And therefore?
VILLAGER #2:
    A witch!

BURN HER!!!!!!!!!!

[hapsh]

If you installed the airbox and the bike ran better, then I can assure you that the carbs had not been jetted properly for pods.

No, you can't really assure me that jetting was not correct, you were not there and don't know that I used a combination of plug chops and an exhaust gas analyzer to find and adjust for jetting settings at different throttle and rpm ranges.  I did have my mixture set very carefully and the engine ran smoothly in all throttle and rpm ranges, however there was still a drop in power in the low to mid range throttle settings below 4k rpm as compared to stock settings.  This I attribute to the lack of the velocity stacks and the plenum box which help tune out the back-flow pulses at lower RPM's that reduce flow into the engine thus reducing power.

I don't own my bike so it can sit in a museum someday long after I'm dead and buried.  I ride my bike.  I ride it hard, rev it up high, and expect it to perform as well as my budget will allow.  If the engine blows up, I'll either rebuild it again or buy another bike.

I'm not a purist, but if you want to be one, go right ahead.  Just don't tell me what to do with my bike.

I am not telling anyone what to do with their bikes, I am just presenting the information that I spent months last year working through.  I also stated I liked Pods in certain situations and actually have used them much more than stock airboxes over the last 30 years.  If I was doing track days with my 550 I would almost certainly use pods or velocity stacks since I would be running at the top end of the RPM band all the time and it would make jetting changes for different altitudes much easier and faster without the bulky stock box.  However, I use my 550 for daily commuting where I rarely go above 5500 RPM so the low end torque I have with the stock airbox is very nice.  I also commute in all weather situations so it is nice knowing I don't have to try to ride home with waterlogged pod filters after a hard days rain.

[nilsey]

interesting discussion all around.

i put k&n pods on my bike (76 cb550) because the airbox rubber was totally shot and i couldn't locate replacement parts quickly. i should also mention i got the bike with some aftermarket 4 into 2 pipes which look like they've been on there for a while.... anyways, it ran crappy in the 3/4 to WOT range after intsalling the pods (not that i knew any better, being new to these bikes and motorcycle riding in general).

last month i rejetted from #98 (i assume they were stock) to #110 main jets. well that sure improved the power at WOT! since the idle was okay and the bike seemed to pull pretty much wherever i was in the throttle, i haven't messed with the other carb setting (idle screw etc) although i will probably get to that....

after about a month abnd maybe 300-400 miles i pulled the plugs yesterday and found them to appear in a good range of operation, with the exception of a little crud around the outer ring of the #3 plug. perhaps a carb sync will help that....

now that i have read (okay..... skimmed!) this discussion i would be pretty interested in going back to the stock airbox and checking it out. if i do i will be sure to post any results i find here, although irt will be more qualitative than quantitiative analysis.

[mlinder]

Well, extrapolating information from the article that paulages linked to, and from how much air the engine would need to receive to have fully charged chambers at 9.5k rpm:

bike could use, all things being 'perfect',

3,496,000 cc per minute


even with larger carbs and port work in the article, they were only flowing

2,030,318 cc per minute (I'm guessing this was maximum flow. Done independently of rpm, just being the max amount of air that can flow, period.)


With, apparently, carbs being the first line of restricition, and then the intake port design itself, as well as cam duration and height.
With the lessened restrictions there, you still couldn't 'gain' any airflow from adding pods (or any other device) unless the stock airbox could not flow 2030317.909 cc per minute.

With the fact that a stock engine flows (according to the article) only 1,551,763 CC per minute, it's possible that the stock airbox and filter are not really restrictive at all, they may just create enough vacuum to keep even draw through each carb, and cause a nice charging effect.


Have to wait for those flow characteristics of the stock airbox, though