New Guy is going to ruffle some feathers.

Twinstar Joined: Jul 16, 2007 Posts: 226 Location: NorCal

Greetings,
I just joined this board/club/forum last week, and after a few long sessions of looking through the various topics/posts and advice given here, I have found that those poor souls who either run or want to run stock CV carbs with stacks or pod filters are hazed or discouraged to do so. Fact: Honda raced and won in the World Endurance Series from 76'-80' with CV carbs mounted on the factory bikes and were virtually unbeatable every year at every round. During the 80' season the FIM endurance rules dictated that the stock carbs from the particular production based engine be used. The racer was the RS1000 and the engine was the CB900F powerplant and the carbs were Keihin VB 51 A with velocity stacks mounted. So, obviously they can and have been tuned to work properly without the stock air box. Imagine that! World Championships won by Honda using a set-up that this site disses.

Posted: Tue Jul 24, 2007 5:31 am

Interesting enough.........

There are some folks on this board that have successfully tuned their CV carbs to run with POD filters and are very happy with their setup.

I did get great results by reinstalling my stock airbox which cured the stumble at mid-range. I do not have the skills or experience to tune the carbs like some folks can so that was good advice for me anyway. I am happy I was pointed in a direction that made my bike work well.

Dave

Posted: Tue Jul 24, 2007 5:45 am

If you are Honda you spend money like WATER and use stuff no one else can get and in fact Honda will not even SELL regular people the stuff they use.

The stock CV carbs do not have stuff available and especially the needle with adjustments,probably because of the tampering with an EPA vehicle deal.

In my case I took a set of 900 carbs with a "K&N" jet kit that came complete with the pod filters and actually TRIED it with open stacks. You can watch the slides flutter around nearly closed even though the instructions with the kit says "works with velocity stacks".

It takes vacuum to make these open. The better you do the quicker they open. Even if they are "jetted" correctly at steady state running does not mean a damn thing if ACCELERATION is the desire,think Miami blue hair in the hammer lane,and that is what the Japanese guy did,made them open slowly on purpose.

The only real world easy to do test is at a drag strip AFTER you get satisfactory running on the road. What you will find out is the ET and MPH will be SLOWER comparing the pod with stock airbox. In fact the reason Honda used the CV's was to make them more controllable in endurance trim,not max power. I remember reading that they tried them both ways back then and the CV's were easier to ride.

Posted: Tue Jul 24, 2007 5:59 am

Posted: Tue Jul 24, 2007 7:22 am

Yeah, I wouldn't be surprised if Honda spent a million dollars "detuning" the bike to run those CV's. I also heard that it was only to help power through the turns, that direct lift carbs made enough power that tire would break loose and possibly toss the rider, or they would be opened too early and motor would fall on its' ass.

Posted: Tue Jul 24, 2007 7:32 am

Hi, NorCalSuperF
Lets trade my cv's for the ones you have on Super F
I didn't think so Mr. Green

I am one of those people that have made the cv's work with pod's and the bike runs like a rocket then I went and put the stock air box back on the bike just to see if there would be any performance gains so far I have lost the crisp response off line 0 to 30 is very dull now but I know my cv's like the back of my hand now when I was running pod's I had to restrict the air flow and use a longer spring on each slide to reduce the crazy bounce they do when i did this the bike pulled hard through all gears and I had no more loss of power at 4500 to 5000 rpm now all I need to do to the carbs is install the stock springs and my 0 to 30 problem will be solved
What I'm trying to get at is why bother with some thing that works, now if you really really want to improve the way your bike runs then just wait and save your money until you can purchase the right carbs to fit your application. This is for all of you who are thinking of buying a jet kit and pods take it from someone who wasted way to much time, effort and money leave them alone and save your money for something better don't be hard headed like I was.

Lurch

Posted: Tue Jul 24, 2007 11:37 am

And after this sucker stops kicking ..
I think I'm gonna invent square wheels ffs ..

Posted: Tue Jul 24, 2007 12:15 pm

PODS on CV carbs looks gay and wrong and it is as simple as that.

CB1100F Joined: Mar 03, 2004 Posts: 3278 Location: Seattle

Rusticles and I have run PODS with the stock carbs for years, with no complaints....... Cool

Posted: Tue Jul 24, 2007 1:41 pm

I cannot attest to actually riding the 1100 I bought that had the jet kit and pods because I quickly dismantled it to fix all the various chassis and other gremlins. One thing it did do was sing like a banshee! It reved like a two stroker! I do know however that sitting next to a bike sounding great in the driveway and taking her down the road putting a load on the engine is not the same, and as yet I havent had the opportunity to test it, (coming soon Twisted Evil

). So I'll wait to make my own judgement as I've ridden with plenty of other F'ers here who ran pods with great success and no complaints.

If what the carbs need is vacume wouldnt properly or heavily oiled K&Ns provide that vacume? I understand getting the right amount of oil and doing it on each pod would be ridiculously hard, I can still see it providing the type vacume needed to lift the slides. I also wonder if Honda had the ability to simply throw in a different slide in their cv carbs that actually lifted the slides via cable. Since a machinist can build damn near anything, why not rebuild the inside top of the carbs to accept a cable and be done with it? Throttle controled slides on CV carb tops.

Also, Pods look great no matter what carbs they are mated to. All that open space makes the bikes look way lighter and very cool. Not to mention the hassle of getting them on and off and cleaning and maintenance is much easier with the stock airbox gone. My first time removing it I was pretty sure honda built the bike around the airbox. What a friggin pain! Rolling Eyes

I will try the set up that came with the bike, then my mikunis, and if that doesnt do the trick, I'll bolt on the FCRs. My biggest problem will be deciding between pods and stacks Twisted Evil

.

Posted: Tue Jul 24, 2007 2:08 pm

larryg wrote:

I will try the set up that came with the bike, then my mikunis, and if that doesnt do the trick, I'll bolt on the FCRs. My biggest problem will be deciding between pods and stacks Twisted Evil

.

I have no choice with that here Larry, the amount of airborn dust around here would distroy a motor in no time! Pods are a must.

Posted: Tue Jul 24, 2007 2:55 pm

If you spend more than a couple minutes online reading about the set up you speak of... The stock appearing CV's that Honda were running were anything but stock... They were designed to run WFO to help with arm and hand fatigue in racers.

But... a person who really knows their stuff could actually tune a set of CV's with pods to work ALMOST as well as the stock air box, so why do it...? If you're such a hot nut then install the slide carbs and pods and feel the difference. CV's and pods will never be as good as CV's with the stock box... and they all will never be as good as slide carbs...

No feathers ruffled, it's not like you're putting them on my bike.. If you want to screw up your bike that's fine.

Posted: Tue Jul 24, 2007 7:40 pm

I raced a 900f with both cv and smooth bores. sm's at least in my experience, much easier to tune .
But way harder to ride longer at full speed. with my bike yank the throttle open and the power came on slowly at first then bang! And the whole bike seamed to explode, great for wheelies coming out of slower corners
but tiring as hell round the rest of the track.
Throttle control took a lot of attention. another reason for dual steering dampers.
Cv ‘s though would act a lot less like a light switch , yank ‘em open and power came on much more smoothly.
At speed much less to keep track of.
My opinion is thats why honda used them, ease to maintain higher average speed, less rider changes and fatigue.
On the street I would keep the airbox and cv’s. choosing pods would be only for looks.
Velo stacks on the street mean new rings a lot more often.

Posted: Tue Jul 24, 2007 8:18 pm

If you have a setup that is so peaky that it explodes in a rush of power then you have tuned it that way whether intentionally or not. It's the whole system doing it, not just the carbs. You go with roundslides that are too big, then they bog and then the power comes on wham. Also, all things need to be considered and tuned from the carbs to the ports, valves, timing, pipes, and ignition. Good pipe tuning and valve timing can stretch out the peak and help eliminate the one trick pony torque peak.

There is no way a butterfly carb with vacuum operated slides will ever work as optimally as a direct lift setup, if it's all tuned up correctly. Just the fuel dropout and vertices in the airflow from the butterflies are enough to do it.

Barometric pressure compensation, however, is something CVc are really good at, as long as you leave the airbox and filter alone.

Posted: Tue Jul 24, 2007 9:08 pm

I agree. I’m just relating my experiences,
just changing carbs back and forth and all else being equal.
And the trouble I’m talking about is what others call stumble caused by
large throttle opening and low vacuum which is what cv's were invented to cure.
When the vacuum and flow reach optimum greater power is made at the same rpm
as you have greater mixture flow into the cylinders.

Posted: Tue Jul 24, 2007 9:11 pm

If you tried several different versions as I have these following things become true.

On the race bikes with dirt simple VM-38 Mikuni round slide open bore carbs would flat break the 8 1/2" slick(7" on the ground) and PAINT a black mark on the ground. Now granted this is 13.5 to 1 compression 1187cc engines(usually),but without accerator pump is still amazing to me that you can get this sudden acceleration.

The CV carbs work best with a sustained vacuum against the aircleaner side afforded by all the carbs drawing on a common aircleaner. The airbox itself without the filter element is still a restriction but it seems to me the drop in type K&N still does not work as well( I have one of those laying around that I try from time to time on various versions).

The human body does not feel constant acceleration as well as it feels the sudden change in acceleration,so if it is only running half assed then "hits" in power everyone thinks this is an improvement. The only way in street trim you can tell this is two bikes that run close,change one and run it against the unchanged one.

You do not have positive control over the slide lift,you just send a "request" for power and wait till the carbs respond. The only comparison is between a 3310 vacuum secondary Holley and a double pumper. The double pumper will bog badly unless/until you get the power valve and accelerator pumps dialed in,and even then you may need a sensitive throttle foot and plenty of RPM to go to full throttle. the 3310 will run with a monkey pushing the throttle because ONLY the primary goes wide open (2 barrels) with the airflow through the primary deciding when the other two barrels opens up. In this case you still get two barrels wide open mechanically. On these CV carbs nothing happens just because you asked for it until it is good and ready to open up.

The power gained and possible driveabilty lost going to real carbs is dependent on the ignition and other things resulting from the motor getting a real charge of fuel/air. Any "bog" is because the air comes and the fuel does not,which is EXACTLY describing a car with a defective accelerator pump. Now all of this does not take into account any EPA mandated emmisions,so it is getting power as lean as possible,the main reason for the CV's.

Now go forward 20+ years to the fuel injected bikes of today. The throat size is emense,like 36-38mm on a 600,but these have a trick. Depending on year and brand,some have the same vacuum piston slide with no needle,others have separate throttle plates controlled by a servo motor. The latest Yamaha is throttle by wire,no connection except electricty. They have done dyno tests on some of the latest rockets and seen the secondary throttle staying almost shut nearing 9000 RPM. If you by-pass this you get more power,BUT you also have the chance to bog trying to much throttle too soon. My son's 02 GSXR 750 is this way. It would be nice if there was an "adjustment" to control the secondary throttle,but it seems to be effectively off and on above a certain RPM with no way to make it a nice progression.

Posted: Tue Jul 24, 2007 9:32 pm

And I really really hope we never have to go through this again just listen to the man above he knows what he is talking about

Posted: Tue Jul 24, 2007 10:08 pm

Pods are like Speedos on a man - they're just wrong.
Whatever performance advantage you might percieve them to give,
I wouldn't be cought dead with them on my bike.

Posted: Tue Jul 24, 2007 10:37 pm

Were is your Rebuttal new guy you should at least give us your professional opinion.
I really would like to hear yours maybe you will convince me to put my gay pods back on my gay Yellow bike so I can go for a ride in my speedos roflmao

Posted: Tue Jul 24, 2007 11:01 pm

Here's the part I don't get:

DynoJet probably did as good of a job tuning their jet kit for the pods and 4-1 pipe as anyone. (Or at least faked it)

Is the headache worth it for that? You could probably just advance your timing a bit and be right there for free????

Posted: Wed Jul 25, 2007 12:10 am

Thanks Sonicrete
My chime in is this
Exiting the left handed bowl at Grattan mi. I yanked the throttle open too early, stumble-bang the power came on
so that the bike stood up and threw me about 25’ in the air, as I’m told, I landed on my head.
Broke the helmet, three herniated disc in the neck, separated shoulder and a bone bruise on my right hip.
I woke up in the ambulance glad to be alive. All I can really remember is yanking the grip.
This was on a 140/80 Dunlop rear tire ‘83

Posted: Wed Jul 25, 2007 12:12 am

Thats the weirdest dyno chart I've ever seen. Why would you swap RPMs for MPHs? Six plus horsepower is nice, but wouldnt you get that in every gear? Anyways, I dont doubt that stock is best for stock carbs, but you'll never convince me that stock airbox looks better than pods.

Even back when these bikes were new you got yourself a 4 into 1 quickly followed by pods. Why? Cause they looked and sounded wicked. Cool

Posted: Wed Jul 25, 2007 12:31 am

larryg wrote:

Thats the weirdest dyno chart I've ever seen. Why would you swap RPMs for MPHs?

To show the MPH gains and make more sales.

Posted: Wed Jul 25, 2007 3:33 am

You just rolled off sooner,but it is the power increase that is important and you were already past the peak.

Power wise,save the money and put real carbs on it. It was several years ago but dealer cost on a pod and jet kit(came in the same box) was about $200. The most money I ever gave for a set of 38mm VM Mikunis was $150.

I have a set of really trick magnesium sand cast smooth bore race carbs. These have all the jets on the outside,that is to say the main unscrews without removing the float bowl,and the lowspeed fuel and air also screws in from the outside. There is no idle stop,the low speed air matches the low speed fuel to make "kind of" an idle. These also have the correct fish hook shape on the locating groove,plugs right on neat.

These have been on and off a bike several times. You need to drill your own jets(there are spare blanks) and I think this was part of the old factory race stuff. When these were tried last they seemed to exibit some "carburetion" flat spots and eventually I just use regular 1100F carbs and airbox on the bike instead of screwing with them. The race bikes got either VM-38mm Mikunis or Lectrons on regular cables which are easier to deal with at the track. These trick carbs I bought just stay in the shelf box.

The way I look at it a dead stock set of carbs works fine and the bike can run easy double the speed limit. The race bikes need to be easily maintained and the rack of carbs just makes that harder to do. The smooth bores used to be used drag racing in the larger bore sizes,but now it is almost totally a Lectron domain.

Posted: Wed Jul 25, 2007 4:47 am

Quote:

Rusticles and I have run PODS with the stock carbs for years

I bought my 900F with pods and stock CV's. Ran great above 4000rpm, but was not crisp below that. Never bothered me, who runs below 4000rpm except in slow traffic. Confused

I started having carb problems last year and got fed up F'n with them and now have a set of CR's...........I'll never go back to CV's Cool

......DOUBLE NEVER CV's with pods, just too much trouble for no gain.

Posted: Wed Jul 25, 2007 3:06 pm

Allright, time to stand up and say that my 750F is one of "those" bikes with K&N pods on the carbs. They've been on the bike for almost 24 years. The PO put them on the bike. When set up correctly, my opinion is that the bike runs a touch lean, and you may lose a few mph off the top end. Otherwise, the bike runs fine. Personally, I think they just look better (see icon).
I think the bottom line is this: if you're a "box stock" kinda F'er, then they shouldn't be on your bike.
If you like to tweak or modify, then it's *your* choice. Debating the tweaks and mods is fun, but there's no right or wrong, just what's right or wrong *for you*.
This kinda debate happens in the collector car world, too. I took a museum level Corvair and put 16 inch wheels, high grade radials, Impala wire wheel covers, improved steering gear, electronic ignition, higher output ventilation fan, a modern stereo, etc into it. Purists were aghast. But most Corvair nuts thought it was cool.
It's whatever trips your trigger. Very Happy

Posted: Wed Jul 25, 2007 4:17 pm

stamper wrote:

...but there's no right or wrong, just what's right or wrong *for you*....

No way man - speedos are always wrong.

(this is just humour Laughing

)

Posted: Thu Jul 26, 2007 3:23 am

The point is that it's a major P.I.T.A. to get them to run almost as well as they do with the stock airbox, but it is possible.

Twinstar Joined: Jul 16, 2007 Posts: 226 Location: NorCal

An interesting slew of responses. One post asks where’s my rebuttal? Rebuttal to what? Where did I say in my post that I was going to run CV carbs and “pods” on my bike? I simply said that others who have come to this site seeking advice on them have been dissed for asking info about running CV’s with stacks or individual filters. There is no doubt that Honda has resources far beyond you or I but, just because you or someone you know could not produce stellar results with the CV set-up does not prove anything except that you or they couldn’t make’em work. As I stated, Honda did make them work. I’ll get to my experience with them in a minute. Sonic, I sense that you have acquired a sort of ‘guru’ status around this site. It’s a no brainer that since the late 70’s almost every motorcycle manufacturer’s combination of stock carb, air box and exhaust has given riders as much smooth, useable power as their particular bike is capable of. Modify anything and carb adjustments will need to be made. You’ve obviously destroyed loads of CB-F engines at the drags leading to your knowledge of what parts will or will not interchange and what cc’s they will yield. You state that the drag strip is the place to prove what works? Not hardly. My personal experience at the strip is that no two launches are ever “exactly” the same on a streetbike. Available traction, clutch engagement and shift points vary from one pass to the next on stock suspension and wheelbase bikes. The only info I’ve ever gathered from the strip is how many passes you can make until your clutch plates are glazed and that you can’t beat the magazine guy’s road test numbers. I don’t know exactly what your bike looks like but, if it’s sporting 8” of rubber, It probably has a 3’-5’ swing arm, cut down forks, air shifter, adjustable rev limiter and a couple inches ground clearance and a typical “ride” consists of turning on the stage lights, peg the rev limiter and release the clutch as fast as possible, from there it’s wide-o through every shift light. My guess is that running at redline for a few seconds is not the real deal for the typical “F” owner. If I were to ever build a “dinosaur era” CB-F dragbike, you would my first call. Allow me to give a little background on where I’m at on the subject of CV carbs and mods to them. It’s 1979 and I’m still completely into dirt bikes (had been since 68’) when a buddy of mine rides into my driveway with a brand new 1979 Suzuki GS1000E. He let me take it for a 10min. ride and I was hooked. A week later I find out that another bud has just bought a new CB750F. Needless to say, after seeing and riding his “F”, that was the bike for me! A few weeks later I had bought my own silver 1979 CB750F. Shortly after that my cousin got into it and bought a black 80’ 750F, we all had a blast! After several months I had low bars a Kerker pipe, Derale oil cooler, a fork brace and some other goodies on the bike. Here’s what was done to the carbs, I picked up a cheap set of stacks from the old Racers Supply outlet in Van Nuys, my Dad made up a set of “snap on” style filter cartridges for each stack, he measured the opening of the stock airbox intake snorkel then grabbed the old Texas Instruments and calculated what the openings should be for each filter and as I remember it, they wound up being a little under the total. The filter material used was a home made double layer design of paper and foam with the paper being cut from a new Chrysler element and the foam was a green Uni-Filter type material. The Kerker I had was originally a race baffle 2” or 2 ½” which we welded another 1 ¼” baffle tube into, raised each carb needle with two paper thin brass washers, and went down one jet size on the mains. The thing out ran every other CB-F bike in our group from starts to roll on response and on the top end by 3-7 mph.
So, CV carbs with stacks or filters are gay huh? You don’t know gay, gay is a 21” front wheel, ape hangers or sissy bars on an “F” in any combination.

Posted: Thu Aug 09, 2007 3:36 am

I'm a picky bastard, so if I have to edit this to read it easier
with myscreen resolution, I may as well share

NorCalSuperF Wrote -

An interesting slew of responses. One post asks where’s my rebuttal?

Rebuttal to what? Where did I say in my post that I was going to run CV

carbs and “pods” on my bike? I simply said that others who have come to

this site seeking advice on them have been dissed for asking info about

running CV’s with stacks or individual filters. There is no doubt that Honda

has resources far beyond you or I but, just because you or someone you

know could not produce stellar results with the CV set-up does not prove

anything except that you or they couldn’t make’em work. As I stated,

Honda did make them work. I’ll get to my experience with them in a

minute. Sonic, I sense that you have acquired a sort of ‘guru’ status

around this site. It’s a no brainer that since the late 70’s almost every

motorcycle manufacturer’s combination of stock carb, air box and exhaust

has given riders as much smooth, useable power as their particular bike

is capable of. Modify anything and carb adjustments will need to be made.

You’ve obviously destroyed loads of CB-F engines at the drags leading to

your knowledge of what parts will or will not interchange and what cc’s

they will yield. You state that the drag strip is the place to prove what

works? Not hardly. My personal experience at the strip is that no two

launches are ever “exactly” the same on a streetbike. Available traction,

clutch engagement and shift points vary from one pass to the next on

stock suspension and wheelbase bikes. The only info I’ve ever gathered

from the strip is how many passes you can make until your clutch plates

are glazed and that you can’t beat the magazine guy’s road test numbers.

I don’t know exactly what your bike looks like but, if it’s sporting 8” of

rubber, It probably has a 3’-5’ swing arm, cut down forks, air shifter,

adjustable rev limiter and a couple inches ground clearance and a

typical “ride” consists of turning on the stage lights, peg the rev limiter

and release the clutch as fast as possible, from there it’s wide-o through

every shift light. My guess is that running at redline for a few seconds is

not the real deal for the typical “F” owner. If I were to ever build

a “dinosaur era” CB-F dragbike, you would my first call. Allow me to give

a little background on where I’m at on the subject of CV carbs and mods

to them. It’s 1979 and I’m still completely into dirt bikes (had been since

68’) when a buddy of mine rides into my driveway with a brand new 1979

Suzuki GS1000E. He let me take it for a 10min. ride and I was hooked. A

week later I find out that another bud has just bought a new CB750F.

Needless to say, after seeing and riding his “F”, that was the bike for me!

A few weeks later I had bought my own silver 1979 CB750F. Shortly after

that my cousin got into it and bought a black 80’ 750F, we all had a blast!

After several months I had low bars a Kerker pipe, Derale oil cooler, a

fork brace and some other goodies on the bike. Here’s what was done to

the carbs, I picked up a cheap set of stacks from the old Racers Supply

outlet in Van Nuys, my Dad made up a set of “snap on” style filter

cartridges for each stack, he measured the opening of the stock airbox

intake snorkel then grabbed the old Texas Instruments and calculated

what the openings should be for each filter and as I remember it, they

wound up being a little under the total. The filter material used was a

home made double layer design of paper and foam with the paper being

cut from a new Chrysler element and the foam was a green Uni-Filter

type material. The Kerker I had was originally a race baffle 2” or 2 ½”

which we welded another 1 ¼” baffle tube into, raised each carb needle

with two paper thin brass washers, and went down one jet size on the

mains. The thing out ran every other CB-F bike in our group from starts

to roll on response and on the top end by 3-7 mph.

So, CV carbs with stacks or filters are gay huh? You don’t know gay, gay

is a 21” front wheel, ape hangers or sissy bars on an “F” in any

combination.

........................................................................................................