Mike's XS pod filters; no internal stack?

[Cesiumsponge]

Hello,

I picked up a pair of Mike's XS #15-0035 54mm pod filters for my Mikuni BS34CVs after seeing how popular they are with other users. I selected it based on the description:

Pod...Features molded in internal stack, no step rubber mount flange and Chrome end cap....

This leads me to believe they had internal velocity stacks to smooth out the airflow of air channeled into the carb versus open pods subject to crosswinds and more turbulent flow without the protection of the stock airbox design (which, while restrictive, is consistent in air delivery). I wanted to run stacks and a filter, but not slip a sock over stacks which disturb airflow, or use cosmetic mesh, which disturbs airflow and filters nothing.

When I received them, I found no such internal structure. I emailed the store for clarity and was told, "I'm sorry we have a new supplier, if the filters aren't working please send them back." To my interpretation, the reply I received implies they used to have an internal stack design but currently sell a cheaper filter at the old price with the old description.

Does anyone have an internal shot of their "old" XS pods? I was unsuccessful in finding any such images. I attached a photo of mine as they are currently shipped. I'd like to try working a stack inside the current pods I have. Returning it and getting hit on shipping AND a 25% restocking fee is crazy; I'd only end up getting the money back on one filter. Otherwise, I'll have to pick up some shorty aftermarket stacks and find another filter that I can incorporate over the velocity stack. Thanks!

-E

 

[jd750ace]

Where did you check for popularity? Uni pod filters have all the universal praise here. Pleated pod filters are the devil. Just what I read here from people that I believe know how to tune a carb.

 

[Cesiumsponge]

I'll look into the UNI pod #UP4229. I've come across numerous posts of people running those or the pink pleated pods (either K&N or I assume a knockoff) in the garage or build threads. I was under the impression the K&N style filters weren't preferred on CV carbs because it has terribly turbulent flow, hence the XS copies advertised with "internal stacks" seemed to fix the issue of getting less turbulent airflow to the carbs...except it appears to be a feature that doesn't actually exist in the product I received.

 

[jd750ace]

I guess that's the difference. I've spent more time on carb problem posts educating myself on potential problems than perusing "build" threads! Not sure about all the turbulent flow stuff, but I'm no expert. I have a generic 4 1/2" K&N hanging off my Road Star and it runs like a raped ape with a CV carb, no airbox. Every carb has it's own flow dynamic and resonance developed with the intake design and valve lift and duration, etc. so as they say, "your results may vary" Only really know enough to get myself in trouble and have to come here and search for answers!

 

[Cesiumsponge]

Yeah, from the jist of reading the carb guide pdf and some of the build threads and tune/idle/flat spot threads, there seems to be some ballpark tips and tuning guides but ultimately, like you say "your results may vary" and no one can give concrete answers on what components or jets will work. I already have a wide variety jets ordered up typical for folks that do pods/pipes. Sounds like it's going to be a very interesting learning experience. This is my first bike and I ended up with someone's project bike so it's me undoing all the things that need undoing and doing all the things I need to do. Should be frustrating but ultimately fun and satisfying! Thanks!

-E

 

[BobbedSled]

I had the same thing with the xs carbs few weeks ago, Got them and said, where r the stacks? I'd love a picture of one, I'd have them made. Stacks inside filters I mean. I assume they are short like these?

 

[Cesiumsponge]

No idea. Perhaps someone with old Mike pods can pull them off and snap a photo. That was really the only reason I gave them a shot. Maybe they were just straight tubes with no real bell mouth. They'd have to be short in any case or it would render most of the filter surface area useless under the entrance of the trumpet.

In any case, it looks like Niche Cycle sells Mikuni OEM velocity stacks for their RS carbs. They share the 55mm flange diameter of the BS34's and come in 15mm to 70mm lengths for guys that have facilities to resonant tune.

One should be able to pick up a cylindrical or conical tapered, 57mm flange diameter filter of 3 to 3.5" dia, 4-6" length, and work the squishy rubber filter flange over the trumpet of the velocity stack and hose clamp them near the base of the stack to create a pod-style filter with internal velocity stack.

-E

 

[weekendrider]

That's a damn serious crimp you have on that cotter pin.

 

[jd750ace]

That's a Hawker style "double tuck" They do all thiers that way on the Hawker line of business jets. It's intended to not rotate in the hole in tight quarters, potentially causing interference with moving parts. It works well, but it's a huge pain in the ass in a lot of locations.

 

[5twins]

Well then I guess he has (or is willing to devote) the time to inferior pod filters that will probably never function correctly. Then, after literally wasting days of your life, don't be surprised if the flanges do this, lol .....

 

[Mharrington]

Back in my watercraft days wed replace the stock spark arrestor/air box with these. Those were 2 cycle engines. After a slight required needle jet adj there was noticeably more punch when you nailed the throttle. I wonder how one of these Flame Arrestors wrapped in a foam pre filter would work on a 4 stroke cycle engine. My bikes run sooooo good with the OEM airbox Im simply not willing to put on pods and attempt to tune. These are Prok brand name

 

[DirtyErnie]

those pods pictured (same as the ones I have) do have the internal velocity stack, but it's a lot more subtle than you're expecting to see. It's the really slight bell-mouth going into the filter. It doesn't take a whole lot to have a major influence on airflow.

If necessary, you may have to clean up a little molding 'flash' inside the filter around the rim of the 'stack'. mine had some things flapping around, but nothing that an hour in the freezer and 10 min with coarse sandpaper couldn't fix.

 

[Cesiumsponge]

That's a damn serious crimp you have on that cotter pin.

That's a Hawker style "double tuck" They do all thiers that way on the Hawker line of business jets. It's intended to not rotate in the hole in tight quarters, potentially causing interference with moving parts. It works well, but it's a huge pain in the ass in a lot of locations.

Ah thanks, I didn't knot there was a specific association with a brand, or even a name for that style of cotter pin termination. I'm going to end up safety wiring anything that isn't recessed into a mating part or using as many castle nuts and cotter pins as I can get away with for the hell of it on the build because I don't want to deal with loctite or nylocks. That cotter pin is on a spherical rod end on the shifter linkage I redid from the PO. The project bike has a lot of stuff that needs undoing and redoing. Cotter pins are a PITA to tuck away nicely. I'm not looking forward to the larger cotter pins on the axle castle nuts, or drilling safety wire holes in hex heads, socket caps, and worst of all, hex nuts.

I have this weird fetish for details no one will ever notice. I've already bought a ton of 1/16" cobalt parabolic drills to prep all the stainless fasteners. Will be doubling up on the safety wire on socket cap screws (don't know the technical term, but you run safety wire through the head twice using two sets of perpendicular holes on the same radial plane). Rigging a new wiring harness with avionics wiring and cable lacing should be an exercise in OCD.

After I get the bike running, I'm building it up in an aviation theme...not so much putting pinup girls and shark teeth paint jobs, but incorporating aviation stuff like safety wire and cable lacing, and even a Kollsman type pitot-static tube to run an airspeed indicator.

 

[TwoManyXS1Bs]

That sounds like fun. Don't forget the tufts of yarn taped to the tank to check airflow...