Topic: 72 cb500 carb tune with pods????

[cb500kawi305]

ive read through a number of carb posts but im not really finding an answer.

Im running pods in a newly build set of carbs. just wondering what jetting i need so my bike will run great and actually idle. bike hasnt ran in 12 years so to be at this point is huge!

if there is any tuning trips let me know!

[DaveBarbier]

You haven't found an answer because there isn't one. What all the posts probably say is that you'll have to rejet because you've made the system leaner.

First, you'll need to go through the 3k mile maintenance. Adjust tappets, cam chain, timing, etc. It's in the manual.

Second, do you still have the original airbox? What exhaust do you have? It's a very good idea to first get the bike running nicely with the stock airbox and exhaust and THEN switch to pods. You'll then know that the issues you run into are strictly a mixture issue.

Lastly, you could be ok with keeping the stock pilot jets but you'll likely have to up the mains and raise the slide needle a clip position or so. (Raising the needle means lowering the clip a notch)

No one can give you the exact jets you'll need to have the bike run right. You'll need to get it together and ride it and perform "plug chops" at various throttle ranges to determine whether it's rich or lean at that throttle range and adjust jetting/needle as needed.

This is a very sore subject. You'll get people yelling at you to put the old stuff back on and that you'll never get it running right with pods. But in my experience, it's possible and all it takes is time and effort.


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[DaveBarbier]

Answer this:

What exhaust?
Motor stock?
What carbs (numbers on side)?
Are carbs spotless inside?
What's you current jetting and needle height?
Do the jets have a K stamp on them?

Do you have money to spend on a dyno? That's the easiest/fastest way to tune.


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[DaveBarbier]

In your other post, Cal has you going in the right direction. You must make sure all else is good before starting to throw jets at it. Do what Cal says and you'll be good to go. Read up on performing plug chops.

[Bodi]

As already said, there's no set recipe for pod jetting.
Pods make a major difference in the carb airflow conditions. Other changes have less impact but do have some: non-stock exhaust, overbore, "hot" cam... these make a difference as well.
Once you have the bike set up with correct valvelash, the ignition timing correct with no issues in the plugs/cables/caps, carbs synced... you can start tuning the carbs. You will either be paying a dyno shop a lot of money, or spending a lot of time at it while becoming an expert at removing, installing, and syncing the carb bank.
Usually one size smaller pilot jet is required to get it idling and running at low throttle well enough to continue. Then you proceed with plug chops and jet/needle changes to dial in the full throttle range jetting. It's tedious. Or the dyno route - but currently most dyno shops don't see carbs and don't have any new jets to use - they can dial in a Power Commander on an EFI sportbike... but good luck finding one that can tune a quad carb stack.
Also - there are some aftermarket "tuning kits" with a variety of main jets to use. Not a problem if you're doing a full tune, but be aware that an aftermarket 110 jet WILL NOT be the same a s a Keihin 110 jet. Start with a set of the kit jets and go from there: if the OEM 110 (or whatever) main is lean at WOT, that does not mean that the kit's next-up size will actually be one step richer than the Keihin one.

[cb500kawi305]

i dont have any original parts for it. didnt come with any. the carbs are newish. i rebuilt them with stock jetting. ignition timing is on point, as well as new plugs and wires. everything on the bike is brand new besides i havent rebuilt the engine or adjusted the valves on her. running i believe stock 2-1 exhaust as well. Ive done the pod tuning process before on other bikes just not with one that hasnt ran in years. i want to know what the best practices are before messing anything up.

[TwoTired]

2 into 1 is not a stock exhaust.  They all (CB500K) came with 4 to 4 pipes.

Know that "PODs" is a style and in no way shape or form a specification.  The flow and pressure drop they have varies among manufacturers, and none mimic what the stock air box provides for carb throat pressures.

The term pods is as specific and explanatory as tires.

[PeWe]

I should install the original filter and make bike to run good since it has not been used for a long time and you do not know the jettings for current setup.
With original setup the jettings are known. When bike runs great which include ignition, change to pods and change what needed.

A CB750 with pods got only larger main jet, set air screws until it pops at throttle off at higher rpm and change until it stop pop. Maybe needles 1 step up which was a must when tuned and pods + 4-1.

Back to basics must be the easiest way to find a start point anyhow.

[Deltarider]

I should install the original filter and make bike to run good since it has not been used for a long time and you do not know the jettings for current setup.
With original setup the jettings are known.

This is good advice. Always try to start at standard. Don't be put of doubting parts like airfilter casings are unobtainable. There must be thousands in the scrapyards and if I'm not mistaking, we have members here that could reproduce them by using 3D printers. Hooray!

[PeWe]

If bike is unmodified it will most likely run better with the box