Uni filters a definate improvement!

[XS650D]

After many hrs dialing in my carbs on my 77D with mikes xs pods i felt that was as good as is gets but i am a bit of a perfectionist and after reading recently (in a Brit MAG) that the diaphram carbs dont like a tapered or ribbed pod filter, decided to give the Uni filters a shot.Well that was the ticket!! Finally throttle was consistent,smoother,more responsive,idled better when started .Really no down side, but to be honest that was after a few laps round the block,tomorrow i will do a good long test ride and see if any glitches show up.I used the Lucas foam filter oil,dident let it dry,honestly couldent wait,just installed and gave er.Gettin impatient in my elder years!! Was actually considering going back to stock air boxes before this but feel that this setup is pretty good and wil leave alone,for now!!

 

[angus67]

Spread the word! All hail unifoam!!

 

[weaselbeak]

Same story here, exactly. Except I don't oil the foam. Sure straightened out the driveability on mine.

 

[angus67]

I don't oil the ones on my 650, but I oil the ones on my marauder. My suzy is my long distance bike, my 650 is for blasting around town.

 

[Snikare]

Are you guys running the UNI filters on BS38s? I just ordered what is labeled as the correct fit for the 53 mm carb opening, and the filters are too big and need to be clamped down enough that it doesn't feel right...! I feel like I'm squashing the hell out of the rubber mount on the filter with that pipe clamp. the K&N filters I have on there fit like a glove, isn't that how the UNI should fit too?

When I look up the fitment chart on the inside of the UNI packaging, the chart lists the sizing as 53mm - 55mm. That would mean that they expect you to have to crush the rubber body to get them on...? That doesn't seem right.

 

[CDNTX650]

Nope. Should fit nicely.

 

[Snikare]

I just found another thread that reads that the filters folks are using are the PK-82, but they are listed as only fitting up to 52mm carbs. I bought the PK-92, listed as fitting 53mm carbs. They are too big. I guess I'll have to exchange them.

 

[davetherave]

I got these for my bs38s

Uni - UP-4200AST 2-Stage Angle Pod Filter, 51mm I.D. x 102mm Length

from ebay seller "speedoutfitters" $16.77 each

They fit the carbs fine and flair out enough to fit my frame.

Best regards,
Dave.

Ps. I removed the outer red filter

 

[5twins]

Yes, you want the slightly smaller size for the BS38s, the 2" size. Believe it or not, the intake bell on the 38s is smaller than the one on the later 34s. Most places base their recommendations on the later BS34s.

 

[Paulrxs650]

Totally agree - i use Ram Air foam pods on my builds, albeit predominately 34s and the difference is very noticeable.
Out of curiosity, I got the last bike, the Cafe Racer dialed in spot on with the Ram Air pods, then switched back to pleated filters. The result was uneven throttle response, especially noticeable and constant throttle, it made the bike feel awful.Switched back and perfect again.

 

[PaulF87]

I've got uni pods on my 38s and love them. I had cones and it seemed to run pretty good until I switched to foam filters, then it seemed to run really good.

 

[angus67]

another thumbs up for post #2

 

[Snikare]

Just adding my two cents to the topic now that I've tried them.
I've recently installed the Uni foam filters. I came from the K&N Pods.

I've had some good trips on the bike now with both the K&N's and the UNI's, and I can't say I see a huge improvement from the UNI's. I started by cleaning my K&N's, running the bike for a couple local rides, and it ran beautifully. I changed the K&N's to the UNI's and have run the bike on some good long rides again. I've noticed only a slight improvement over the K&N's in the area of smoother throttle response while cruising at a steady MPH with only moderate throttle fluctuation in 3rd, 4th, or 5th. When you get on the throttle I think the carbs are just pulling so much, that you wouldn't notice any difference between the two. However it is a nice improvement while cruising.

I've noticed that most of the people I ride with and the bikes I see pictured here have dirty sometimes filthy air filters. And, I think what people are noticing most when switching is a CLEAN set of filters...

I've always been really on top of cleaning my filters, I live in a dusty county area. Cleaning the filters often, has always been necessary. And the change from filthy filters to clean, is ass puckering... I like the look of the K&N's more than I like the look of the UNI's. So when I feel I need to put the K&N's on with the chrome ends, I'll do it but make sure that they are nice and clean. But because of the slight gain of smoothness while cruising. I'll keep the UNI's for most of my riding.

If you have pleated pods and you're on a budget, just make sure you're keeping them clean is all. I don't think the purchase is necessary. However if you don't have filters yet for your bike. And, you have to choose between the two. The UNI's do make a bit of an improvement and cost less than the K&N's.

Hopes this helps.

 

[richie]

Hi, did the PK-82 fit better?

 

[XSLeo]

The PK-82's fit the BS38's, the OPK-92's fit the BS34's.
I have both sizes.
The area that is most effected by the K&N style pleated filters is just of idle and at a steady cruise. The pleated elements cause too much airflow turbulence through the carbs. This effects the slide lift. This gives you the off idle flat spot. At steady cruise the poor vacuum signal lets the slide flutter.
Leo

 

[angus67]

For what it's worth, my 71 has stock filters, and they are ribbed paper. Could it be that the 34's have the most issue with this? I'm tempted to buy the foam pods for it to see. It does run sweet in stock form.

 

[fredintoon]

Hi angus,
FWIW the stock system has the carbs sucking air through whatever filter medium, (pleated paper like yours, teddybear fur like mine), via a plenum chamber so the intake air is pretty much calmed down by the time it gets to the carbs no matter how disturbed it became while going through the filter to get in.
OTOH pods are mounted directly to the carb intakes so it's the smoother the better for them.

 

[angus67]

Actually the way the stock air boxes are designed, they are nothing more than a metal cage to help support the carbs. No real plenum

 

[peanut]

I got some of these beauties from Ramair but haven't had a chance to try them out yet as my battery was flat due to all the carb setting testing that I've been doing lately

Wasn't going to oil them unless they don't work satisfactorily as is.

I thought the idea behind the original air boxes was to have a reservoir of air immediately available for throttle response that was uneffected by air turbulence around the carb intakes ?