Want to buy carbs that WORK with pods?

[MarkPBG]

I was wondering with all the talk about the original carbs being the kind that generally work best with an air box, are there aftermarket carbs out there that are designed to work without an air box, out in the open with stacks, or with pods? It would seem that If I do want to go with pods in the future, trading parts for a set of the kind that WILL work with pods would be smart, IF there are any brands of carbs that do work well with pods.

Does anyone know of any? Are the Mikuni carbs a little less finicky about having an air box, or is the dual two barrel kit from Cycle X the only game that runs well that way?

[Piute]

 


                 Hey Mark talk with this guy     http://www.satanicmechanic.org/carbs.shtml

                                           1st part of his read on carbs

Carburetors
Stock carbs are 28mm. The basically come in three varieties:  The very early carbs which had four individual cables and probably were a nightmare to synchronize. The majority (K1-K6, F1) were linked and had the choke lever at the carbs.; Latest carbs were jetted leaner (to comply with emission regulations) and had a accelerator pump to make up for the leaner mixture. Rumor has it that the late K6 models had 26mm carbs but I never was able to verify that.

For performance applications, I found the K1-K6, F1 carbs the easiest to work with, if you want to stay with stock. Some people bored them out to 30mm. The late carbs have pressed in pilot jets which cannot easily be changed.

If you are looking for more power, there are aftermarket carb banks from Keihin, Mikuni and Dell'Orto which fit the 750.

Depending on the engine's displacement, and the application here is a rule to the carb size:

750cc 29-30mm
836cc 31-32mm
900cc or larger 33-34mm

For roadracing (if you are ready to sacrifice bottom end for top power) you may use one notch larger carbs

[MarkPBG]

Thanks Piute, some good info there. :)

[LukeM]

I looked at a buddy's Rebel engine yesterday, and saw Honda uses a manifold and a single carb.  I'm guessing you could do the same with the 750, but the runner length being different could cause some performance issues.  Maybe 2 manifolds and dual carbs?  Again, I'm thinking the Honda engineers thought about that (they thought about everything else on the bike), and decided 4 carbs made for better performance, and probably more revenue for the dealer in terms of carb adjustments, service time, etc.

Luke M

[shinyribs]

I have been watching all these posts about pod issues. Really,if you have the old round top carbs its not that bad at all.The crosswind thing is there,but if I can "cure" that by tucking my ankles up tight I'm sure a simple deflector will work.I just havent gotten around to it yet.

I swear if I had a DOHC I would spend all my time on getting a set of round tops fabbed up on there.It could not be that difficult.

[MarkPBG]

I was thinking about a deflector last night. Started making some sketches. Just a simple curved triangular (or half-conical?) plate, big enough for air clearance around it, but also big enough to block crosswinds. I want to make one that has a collar on it I can either clamp or zip tie right over the intake boot clamp. Or maybe one that screws to a little tab hanging off the frame…i think it would look cleanest if it were shaped sort of like the pods, and fastened right to the boot area somehow.

[Piute]

                                          Moveableblockers

[shinyribs]

Here ya go Mark. This is what I am planning on trying for a deflector. The "pods" on mine now are  valve cover breathers we carry at the speed shop.I shoulda used these.Didnt know about the whole crosswind thing at the time.I figure you only need two.One for each outer side,though two in the middle with the shields on the bottom wouldn't hurt.

http://www.speedwaymotors.com/Valve-Cover-Shielded-Breather-1-3-8-Inch,463.html

[MarkPBG]

Well, that's an easy solution.

[Lucky 1]

WRONG...Sorry but too much confusion here.

You can make any carb work with "pods" which have
very little air intake restriction.

The problem is that owners just do not know how to tune a carb.
 Thats the truth.

It is sad to read the stories on this site and others that tell you that to get the
bike to run correctly, you must put the stock air box back on the bike.

If you put stacks or pods on your bike and you have a high
performance after market exhaust you will need to re jet your carbs.
This does NOT mean that all you have to do is to put in a larger main jet.
You will need to increase the idle jet size that controls the fuel flow from idle to 1/4 throttle.
You will need to raise the needle in the slide by lowering the clip on the slide needle.
The slide controls the throttle from 1/4 to 3/4 throttle. Otherwise MOST of the use of the throttle.
You will also need to increase the size of the main jet which controls 3/4 up to full throttle.
There is a little but of cross over.
But you cannot just increase the main jet and call it good.

On these older engines you need about 14 parts air to one part gas.
A modern car engine with direct injection into the combustion chamber
is now 65 parts air to one part of gas!

If you go to the CB750 chopper website you can get better info about setting up your
carb with stacks or pods because they did it for YEARS.
You will not hear those people saying you have to put your stock air box back on.
Trust me..the chopper people always find out how to do it .

Oh, one more thing...

You CANNOT just buy a set of carbs, bolt them on and it runs perfect. Forget that.
You will have to do some work.

If you do not want to do ANY work, just put all the stock parts back on.
But you will still have to adjust the mixture screws as outlined in the workshop manual.
 

[MarkPBG]

That's what I thought, as carbs on cars can easily be tuned to run with nothing on top, stacks, air filters or cold air boxes. What about the crosswind "myth"? Seems to me that would just introduce more air into the carb, but the way the carb is tuned won't necessarily let more into the engine, right? I know that's a gross oversimplification, and it may even be wrong on the whole, but I have no technical training in automotive mechanics, I'm a parts changer and a "tweaker".
I did get the feeling that the carbs could be made to run on pods just fine, but the tuning was going to be a little more involved that a jet change and a mixture screw turn. I have two great shops near me that work on old bikes, and BOTH field a vintage race bike/team, so I'm sure anything I don't have the skill to do, these guys can do for $65 per hour. LOL

[Piute]

                               Couple hours well worth it ,you get the parts ,Gurantee there work.
                                                                         

[MarkPBG]

I already have the parts! Waiting for an opening in their shop schedule. :) Should be up and running within a month. :) I got all the safety and maintenance related parts, cables, brake pads and shoes, carb kits, spark plugs, rectifier, voltage regulator, battery, wiring harness. The only things I don't have are tires, tubes, chain, and master cylinder kit. I'll probably get the brake fluid flushed out and changed too. Wish I had more time to work on it myself, schedule is too hectic for the next few months.

[Piute]

  Hey tell me
  Having mine just setting cause I'm to dang tired ,but hours are slowing didn't have to work today(sunday)
 Had church and house hunting (place closer to work)Don't plan to move till winter Maybe
  I have a matching tire coming and will have a near new tire setting around It's A Dunlop Elite II, 18" good luck trying to find one ,I tryed to find a $
  Thinking super coils and ingnition stuff next.

[shinyribs]

Re:crosswinds. It's real.  I would love to learn how to "tune" around it if anyone has a suggestion. Here's the deal. If the crosswind decides to blow INTO your carbs.Fine.Air is supposed to enter the carbs.All is well.But when the crosswind sucks the air OUT of your carbs...uh...thats pretty much impossible to tune around.

Ever run a car down the road with no hood and no air cleaner? If you do and you move fast enough it'll spray gas on the windshield.Its sucking the fuel/air mixture out.

An NHRA or IHRA track will NOT let you run down the track with an uncovered carb.You must either have an air cleaner,hood or what they call a flash shield.

The flash shield is appropriately named. No explanation needed.

Carburetors in the open winds cannot ingest and meter fuel properly.They are designed to meter fuel according to vacuum signal,but only ONE way! IN!

On these bikes the carbs are already trailing behind. I imagine the wind doesn't whip inside the frame rails too bad and it makes it do-able under normal wind conditions

My bike is running faster than everyone says it should @ 140 mph. My plugs read out a perfect even mixture on all four cylinders. I also get better fuel mileage than people say I should be getting @ 45-50 mpg on the highway.I am no bike mechanic at all. I tuned my bike according to the advice and knowledge of the local bike shop owner/mechanic. He loves the cafe scene and loves jap bikes. He knows his stuff as far as I am concerned.Once I thought I had it right he rode it and said it felt strong and agreed the plugs read proper. So maybe my carbs are way out of tune and I should be able to tune the wind out of them. I am open to any and all suggestion as to how to cure the crosswind blues,cuz they suck!

I have had a lot of open air engines.Here are a few of them.This is my first bike,but not my first rodeo.Carbs do funky things when the wind sucks the air out of them.

[Lucky 1]

You are right Plute... but these effects are mostly at high speeds.

The riders knees sticking out help to disrupt the draft.
Road racing bikes that operated at high speeds with stacks usually had fairings.

I would say if a owner is experiencing problems about loss of air on those
outside carbs, a small plexiglass shield could be attached to the air cleaner brackets,

BTW I like that blue and yellow rail. Very classic.

[slownugly007]

Hey mark, what shops are in this area? I want to look into getting my carbs synched up, Im open to do it myself but dont really have a good place to rev up my bike constantly, my apartment kinda frowns on stuff like that? but that hasnt stopped me from making tons of noise/progress sounds on my bike! lol I swear I feel like my neighbors think im a mad scientist cuz my bikes on my patio, but I have full, thick curtains covering it so all you can see is my silhouette and hear loud noises coming from behind it every night as I work on my bike. muahahahahahaha its aliiiiive!

[MarkPBG]

Well, there's one in Lake Park, one in Jupiter, three in West Palm, and another in Lake Worth. Are you near any of those areas?

[MarkPBG]

You know, it never occurred to me about the air rushing by the carbs actually creating a siphoning effect and completely negating the incoming air charge, or even reversing it! That makes sense. I've never raced an open carb car or bike, so never encountered it first hand. The old timers were too busy at the track making money to share their experience.

[Piute]

   Mc Ribs
              "On these bikes the carbs are already trailing behind. I imagine the wind doesn't whip inside the frame rails too bad and it makes it do-able under normal wind conditions "

  On A Harley the rear cylinder stays cooler then the front ,Cause the air circulate all around the rear. Pod are do able but having the experience Or getting with your own no how or not to do how,Blowing out exhaust- sucking air carb. all has to be regulated for the ridding style your going to be doing.As some-one said if you wont looks get a detachable type clamp,that may be easyer
                       
     
  Hey Chrome guy By the way those rocker covers wouldn't fit to short