Pod Filter + CV Carb

[full on tin]

We've all seen the thread before. "I want to put pods on my carbs, but word is they are a fuss to tune/jet)"
Typical response "don't bother with that, keep your stock box on"
...then a pro chimes in "it can be done, you just have to get the jetting right"

MY bike: '80 CB750F DOHC

Solution ONE:

+ a solid Rejet setup
http://www.dynojet.com/jetkits/index.aspx

Would a 'manifold' type filter maintain the 'Constant Vacuum'? Also less effected by crosswind/turbulence?
Solution TWO

Input would be a great help...

 

[Big R]

I've never had the pleasure of tuning an inline 4 with pods, but my understanding is one if the problems is the outer carbs (#1 and #4) get the coolest air. Which makes sense: any air coming off the engine is going directly to the middle carbs. K&N makes a double filter (nicknamed a lunchbox filter) so one filter would work for the 2 carbs on the left, and another filter for the carbs on the right.

As far as the "vacuum" part- I believe that has more to do with the length of the intake between the carb and the filter (and also the volume of the stock airbox).

But wait for a pro to chime in before spending cash on my advice.......

 

[YogiBear]

the pods will work for your DOHC. I've had them for over 3 years with stock pipes. Will the bike run perfect? no, but it will not be a noticable difference. you will have to play around with the jetting a bit if you have aftermarket pipes.

 

[my-79-750-k]

Yes it needs to be fine tuned with the jetting, but a 50$ dyno run with A/F readings will do a lot to point you in the right direction. Ive got pods on my 79 with stock carbs and a 4-1 header, and it runs just a touch lean at 6-7000 rpms, but that'll be fixed this winter.

 

[full on tin]

The ITG filter Bar's are not too expensive ($100ish) so the same as K&N. and if it makes tunning easier and performs better, I would like to go that route.

 

[hellhound1]

I too am very interested in a good answer to this. It seems as though so long as you have the patience, you can make them work. I was blasted with so much negativity I haven't even tried to swap out the box, but I would love to.

We've got all winter to work on the bikes so I'm gonna shoot for it.

 

[Swapmeet Louie]

I too am very interested in a good answer to this. It seems as though so long as you have the patience, you can make them work. I was blasted with so much negativity I haven't even tried to swap out the box, but I would love to.

We've got all winter to work on the bikes so I'm gonna shoot for it.

You've got it...

There is no other definite fix or answer other than patience and persistance. Each bike will generally be a little easier. What works on one cb750 wont be perfect on another. And that goes for any bike make/model...

Pods will tend to make you run a little lean from iddle-3500. Again that differs from carb to carb/ motor to motor...

 

[flatcurve]

Don't waste your money on pod filters and jet kits. It will be nothing but a headache. I see this topic pop up every few months on any one of the handful of honda related forums I'm on (which is why the guys at cb750c.com are so testy about pods), and the result is always the same.

"I think I can make it work"

"No you can't"

"Yes he can, he just has to be patient and buy a lot of jets"

and then the thread dies... I haven't seen one person ever come back saying that they've done it successfully. There's a big difference between just getting it to run, and getting it to run well. I've seen plenty who say that the bike runs with pods, but there's always some sort of capitulation involved. i.e. poor high end performance, or the bike won't idle, etc... But nobody comes back to say pods on cv runs better than stock. And that's because they can't. It's more than just a jetting issue. The design relies on the vacuum created by ganging up all the cylinders on a common restricted air intake to lift the slides. Anything that will work on the bike besides the stock airbox will always be an approximation of that airbox. That filter bar may not be enough.

That being said, I'm not trying to shit on your parade here. The guys over at deuces wild have taken a few stabs at this. There's an epic thread about building an alternative airbox over there:

http://deuceswild.yuku.com/topic/1051/custom-Airbox-build-Breaking-News-10-08-2010#.TsaPpcOy7Ck

that might give you some ideas. Otherwise, your choices are CR carbs, CycleX carbs, or taking a stab at fuel injection.

 

[crazypj]

As noted above, you can make it work but you can't make it work properly.
It's actually more involved than just swapping jets, there are several other modifications that need to be done to various parts to get close to stock performance at all throttle openings.
A change in diameter of less than 0.003" in air corrector jets or emulsion tube opening/bleed hole make's a massive difference.
Also, each engine is slightly different.
It's time consuming and frequently frustrating to improve performance over stock but is possible
BTW, I've been modifying carbs for about 30 yrs, it depends how much inconvenience your prepared to put up with or how much your willing to spend on dyno time/testing

 

[veloracermike]

My bike came with pods. At this point, after reading all the negative posts about pods I'm leaning toward selling them and going another route for my air filter. Anyone interested in a like new set of 35mm K&N's?

 

[crazypj]

350f has pretty 'crude' carbs so isn't as difficult to jet compared to later models.
Saying that, I may have astock airbox for CB350 F, I'll take a look tomorrow (although I haven't had much luck finding stuff so far )

 

[Swapmeet Louie]

Don't waste your money on pod filters and jet kits. It will be nothing but a headache. I see this topic pop up every few months on any one of the handful of honda related forums I'm on (which is why the guys at cb750c.com are so testy about pods), and the result is always the same.

"I think I can make it work"

"No you can't"

"Yes he can, he just has to be patient and buy a lot of jets"

and then the thread dies... I haven't seen one person ever come back saying that they've done it successfully. There's a big difference between just getting it to run, and getting it to run well. I've seen plenty who say that the bike runs with pods, but there's always some sort of capitulation involved. i.e. poor high end performance, or the bike won't idle, etc... But nobody comes back to say pods on cv runs better than stock. And that's because they can't. It's more than just a jetting issue. The design relies on the vacuum created by ganging up all the cylinders on a common restricted air intake to lift the slides. Anything that will work on the bike besides the stock airbox will always be an approximation of that airbox. That filter bar may not be enough.

That being said, I'm not trying to shit on your parade here. The guys over at deuces wild have taken a few stabs at this. There's an epic thread about building an alternative airbox over there:

http://deuceswild.yuku.com/topic/1051/custom-Airbox-build-Breaking-News-10-08-2010#.TsaPpcOy7Ck

that might give you some ideas. Otherwise, your choices are CR carbs, CycleX carbs, or taking a stab at fuel injection.

I've run pods and or Velocity stacks on every bike I've built. With success... Some where in the neighborhood of 30+ bikes. Anyone who cant, shouldnt be tuning a motor.

 

[crazypj]

Louie, some CV carbs just don't work very well with 'pods'
The Honda DOHC 750/900 is one of the bikes where just swapping jets doesn't work.
You can make it run OK-ish but it will never be 'right' without some extra modifications

 

[Swapmeet Louie]

Louie, some CV carbs just don't work very well with 'pods'
The Honda DOHC 750/900 is one of the bikes where just swapping jets doesn't work.
You can make it run OK-ish but it will never be 'right' without some extra modifications

Right! Extra modifications. Any one who expects Universal parts to work right off the shelf and be plug'n'play is nieve ...

 

[flatcurve]

I've run pods and or Velocity stacks on every bike I've built. With success... Some where in the neighborhood of 30+ bikes. Anyone who cant, shouldnt be tuning a motor.

I'm talking about using them on the DOHC hondas with the CV Keihin carbs. I know that pods and v-stacks will work on other types of carbs or bikes.

 

[Swapmeet Louie]

I'm talking about using them on the DOHC hondas with the CV Keihin carbs. I know that pods and v-stacks will work on other types of carbs or bikes.

Even your link that you posted about the modified air box is using a pod right... So they do work. As long as your brain does. They are like a tool, only as effective as the one wielding it.

 

[flatcurve]

Even your link that you posted about the modified air box is using a pod right... So they do work. As long as your brain does. They are like a tool, only as effective as the one wielding it.

Yeah, but that's a single pod for the whole bank of carbs, as opposed to having a pod on each carb. The point I was trying to make is that these CV carbs work better when pulling from a common intake. Believe me, I'm not against pods at all. I've got them on my own DOHC CB750, but I'm not running the stock CV carbs either.

 

[Swapmeet Louie]

That stands for CV carbs across the board. Doesnt matter what they are bolted too. And I'm not trying to be a dick. I think this is a great thread and can benefit alot of people that lack experience in the topic. I guess my personal belief is, "where there's a will, there's a way" is all...

 

[teazer]

Back in the day, a guy named Leon Moss from LEDAR was trying to modify a CB750/900 DOHC and that guy knew more about carbs than most people on the planet. He ended up with all manner of changes to get those carbs to work sans airbox and with a 4 into 1 pipe. A:F was all over the map and yes he did manage to work out a way to do it, but the solution was way beyond most of us let alone the neophytes among us.

Late model GSXR carbs by comparison appear to be quite easy to jet for pods, but some of the early DOHC Hondas were a PIA and for most mere mortals they are best left alone.

 

[mrwolf]

I'm sorry and I don't mean to offend any forum veterans and I am only speaking of personal experience here. I completely disagree with everything being said that its impossible to run stacks/pods on cv carbs. I have always run stacks on my 3 bikes and they all have cv carbs. It's just a matter of tuning, finding the right jets, shimming the needle, adjusting the mixture and some patience. IMO if done correctly running stacks on cv's really brings them to life.

I'm only 26 and I haven't been building carbs for 30 years, but I still think that it's still just physics and with the right approach everything is possible.