pod filter tuning

Tyler H

XS400 Member
Messages
19
Reaction score
1
Points
3
Location
co
Hey everyone,

My bike is pretty much complete (I'll post pics soon) and I'm messing with idle and throttle response and I had a question based off of a youtube video I saw. I have the pod filters on my bike and in the video the guy pulled the rubber mount from the inside of the filter and said it blocks passageways on the lip of the carb and to cut them away. I know my carbs are pulling too much air with these and I have my fuel mix backed out quite a ways to compensate, i think 5 turns out from seated. It idles fine with choke on until it warms up and then I can push it in and if you roll on the throttle it runs pretty good, but if you dump the throttle it wants to bog and die. Should I get a size up in the pilot? should I cut these pod filter interfaces to better allow flow (not sure what the ports on the back do?)
 
You need to go up in jet sizes, and need an interface between the pods and carbs as the pods directly on the carbs create turbulence/irregular flow besides partially blocking air intake ports.
It is quite the job tuning for pods, am in it as we speak so I can tell.
I am right there at least in the shop have not tested under load as of now but starts right up and revs good even with "shitty" pods.
 
Don't know why most everyone thinks jetting will need to be increased. :shrug:

Crappy pod filters cause turbulence. By increasing turbulence, one is reducing airflow. Therefore less fuel is needed to maintain the correct air:fuel ratio, resulting in smaller jets being needed. Burn less fuel, and of course less power is made. :eek:

But don't let science get between you and your dreams of being featured on pipeburn. :pimp: Pod filters rock - if posing for photos is your goal. :thumbsup:

Stop blindly following the wrong advice found all over the Internet and start thinking for yourself. :umm:
 
Are you saying you went down in jet size Dave?
Yes, but what I've done is not important to you, unless you have the same setup as I do. My current setup is as follows:

DOHC engine with Uni filters on stacks and working crankcase ventilation.
JBM Industries diaphragms.
Stock head pipes with HD Sportser mufflers.

My jetting and carb settings currently are:
120 Main Jets
Needles fully lowered (clips in top groove)
Fuel level 2mm below stock
45 Pilot Jets (stock size)
Pilot screws adjusted for highest idle vacuum reading, turns not counted but may be 3 or so.

Again, unless you have a DOHC with the same mods as mine, this info is of no use to you, other than being another example to mislead you! I know the needles are showing noticeable wear and should be replaced, what do you expect with over 100k km / 62k mi on them? I haven't found the correct needles and can't be bothered to buy full carbs. I know that the mufflers are a big issue as they are way too free flowing. They are causing reversion pulses, as evidenced by road dirt being sucked into their outlets. That is not good. I'm considering welding some washers into them to provide some restriction until I can have a new, quieter system designed and built. The Pilot jets are slightly too large as I get a stumble off idle with the engine warmed up. And I may be slightly low on the fuel levels as I get a slight surging around 7k RPM with lots of throttle.

Isn't modifying CV carbed bikes fun? :laughing:
 
Ok...was under the impression that you went up to something like 145-147,5...ish.
I personnaly went for 45-145 and needle 2 out of 5
And 3 turns out...Pods:rolleyes: but on the stock air intake boots that fit nicely INTO the pod...so Nice smooth edge for the air to come in and stabilize...
Fired Up like a champ, idles nice and steady, revs nice and even all the way Up to full throttle.
That is all while sitting...still need to "Read the plugs" and test under load.
But this will have to Wait has I have found that I have a small oil leak at the front end of the crank case:banghead:
 
Last edited:
A couple or 4 years ago, when I was running different mufflers, crappy pods directly on the carbs, and had a failing TCI module, I did have massive jets installed. Then I had to replace my TCI module, install (somewhat) quieter mufflers, and made the stacks to install the UNI filters. So, up until last year the bike was in a state of constant change, which made it difficult to nail down the jetting. Last year was mostly just riding and regular maintenance, so I was able to spend more time refining the tuning and performing long term testing. I can now hear the difference between "warm enough to idle nicely without choke" and "actually at operating temp". There are some days where it never gets up to operating temp no matter how long I ride. I've got it close enough that I can ride every day without concern, but it still isn't perfect. After riding some fuel injected bikes, I have a good idea what I should be aiming for.

If your bike is running decent right now, I'd guess that it is jetted rich. It is very difficult to get the engine up to operating temp without riding it fairly hard. Time will tell.
 
Back
Top