An attempt at pod customization (440)

I want to try and customize a set of pod filters for my 440 bobber project. Rather than building a box, I believe I can just insert a choke into the filter to restrict the airflow.

I was thinking about trying 1" inlets to start, I'm not too keen on how to calculate the volumetric efficiency but I figure i can keep shaving away parts of the reducer in case the inlet must be made larger.

I plan to run the 97.5 jets rather than the 102.5s.

Any advice would be well appreciated.

Will post results!

:whistle:

I'm assuming your bike has the stock CV type carbs. If so, good luck with your experiment - it's worth a try. Take a look at the video in the link below as it shows how CV carbs work. Notice they depend on vacuum through the throttle vacuum passage to raise the diaphragm which in turn raises the jet needle. With an air box there is normally some level of vacuum in the box when the engine is running since one or the other cylinders is drawing air from the box. Without the air box the vacuum normally present on the intake side is absent, and that changes the vacuum level at the throttle vacuum passage which affects the diaphragm and the raising of the jet needle. This makes tuning the CV carbs for pods very challenging. Ed

It could end up like this.
losangeles.craigslist.org/wst/mcy/5297939256.html
Or this,
sandiego.craigslist.org/csd/mcy/5259934323.html
Maybe even like this,
inlandempire.craigslist.org/mcy/5303879432.html
Once done it will never be like this again.
sandiego.craigslist.org/csd/mcy/5277950270.html
BTW, no one is buying.
Steve

Fortunately I am not dealing with 4 carbs so it shouldn't be too bad. Id rather the stock airbox however, I only have half of it. So of course, I'll turn to fabrication. We'll see how it goes. Have new exaust pipes on the way, as well as the parts for my pod build. If it works i"ll be a happy kzrider. I've heard of people overcoming the pods through jetting and needle placement but id like to try and keep it close to stock with what I put together.

KZR topic --- Custom Air Box for KZ440. In case you don't see it, there's a link to a cast aluminum box after the first photo.
(amazon.com --- CU-476 Aluminum Econobox).

I have a 750 four with pod filters that will rip your arms right off if you are not careful. Pods can be done, but honestly are not worth the hassle in my opinion.

I also have a 440 that flat out refused to run without the full airbox. I found the lid or snorkel on eBay for $25. It ran like a champ.

If you really really want pods, it is much easier to just buy some mikuni round slides and go from there. Several places even sell prejetted kits.
www.speedmotoco.com/mobile/Product.aspx?id=2683
B

If you do manage to get it running correctly with pods, definitely do a write up on it. Many people have tried, but few have pulled it off.

Okay so I finally got around to this project. It's been real cold here in PA and I don't have a garage so doing work on the bike has slowed.
Anyway my Idea was to port the pods to reduce airflow so I could go down to a more reasonable jet size. I chose 97.5s from the sigma jet kit on eBay.
I acquired 1.5" to 1" sch40 reducers off this site www.supplyhouse.com/Spears-429-211-1-1-2...Mpr39Lue-BoCVeHw_wcB





As you can see they fit very nicely into the pod filters I have.
Next, I cut down the reducers and made them fit more easily into the rubber by grinding down the diameter on the conical portion of the reducer.












Inserted the reducers into my pods and affixed them to the carbs. Here's what they look like. I believe the reducer sleeve sticking out into the pod will reduce the effect of crosswinds.




I turned it over and it started right up with no choke after sitting cold with an outside temp of 45°F.

It runs smoother than it had previously in my opinion. I'll have to mess with it more. It's soon to have new exhaust pipes (WITH BAFFLES) and I'm excited to see how it affects performance.

My biggest issue I've been having since the start of all this is that I lose a lot of power at midrange and end up having to shift around 4k.
Would shimming the needle help with this at all? I also think somebody messed with the idle screw. I set them to 1.75 turns out from snug. Would anybody be able to let me know what their idle screw is set to so I can start from a more stock position?

Here's my project so far btw. 1980 KZ440A ltd. Started with a frame and an engine and I found everything else from donor bikes. First bike.

I've been thinking about this problem with CV and pods. I understand why tuning is difficult but I all I've seen is playing with jet sizes and needle height. The base problem, as I see it, is the incoming air passing though the throat actually causes a vacuum which lifts the slide. Bernoulli principal of fluid dynamics. Now the problem with running pods is that the ambient air pressure in the pod is basically outside air pressure while the air pressure inside the air filter box is lower than outside pressure. Because of this the slide is easier to pull up.

So what I was thinking is what would the affect of cutting the slide return spring down a turn or two. Less spring pressure might just help. That being said I wouldn't cut my springs. They are too hard to find and too expensive. But if a guy had access to some junk carbs to play with? Would be a whole lot easier to tune since moist of these bikes you can remove the cap and springs while the carbs are still installed.

Just brainstorming here. Never heard of it being tried.

Looks like you need carb holders.
Steve

swest wrote: Looks like you need carb holders.
Steve

so you don't think all that red RTV is OEM?

When I started out on the bike I bought brand new carb boots. They don't seal very well. So I put a minimal amount of rtv sealer on them. I kept checking for engine leaks in that area and putting it on then realized it was a broken rubber cap on a vacuum stem. So now theres a bunch :pinch: