Is there a Uni Filter for the BS34 carbs?

[Jerm]

Thanks in advance.

 

[Inked Monkey]

Pretty sure 650central has the foam ones and mikexs has the k&n lookalikes.

 

[5twins]

Uni doesn't make airbox replacements for the XS650 but you can get pods. The BS34s have an intake O.D. of about 2 1/8" so you'll need to use the 2 1/4" I.D. Uni pods. You can get the plain black foam one (part #UP4229) or the dual layer version (#UP4229ST) for a few dollars more. The BS38s have a smaller intake bell diameter (about 2 1/16") so you can use the 2" I.D. pods on them (UP4200 or UP4200ST).

All of the above are the 4" length. Anything longer won't fit between the carb and battery box. Here's a UP4200 I recently installed on my 38s - fits like a glove .....

According to the Australian Uni web site, you shouldn't oil these with the normal foam filter oil. They're made of a fine foam and the normal oil is apparently too thick. It will clog them and cut down air flow. Instead, they recommend oiling them with a 50-50 mix of gas and motor oil. I used a mix of gas and straight 30wt. on mine.

http://www.unifilter.com/online catalog/universal.html

 

[tor_bjorn]

Hello! Bringing an old thread to life--
I ordered these UNI filters but received one size too large. Need the 2" ones, you are spot on. Will the intake be effected too much if I use tubing -or something heat resistant- to make em fit snug around the intake? As long as I don't block any air lines..
Thoughts? May as well try, but thought you pros might have a suggestion or input.

 

[Brian902]

You could probably find lots of things to fill up the space, but really, order the right size and be done with it.

It will just end up being a pain in the ass otherwise.

 

[Megatron]

This is probably a stupid question, but when putting these foam pods on, I just take the air box off and strap these on instead, thats all that needs to be done? It seems too easy. Will I need to do any jetting, or can these just be thrown on instead of the airbox?

 

[littlebill31]

The boxes will need to be removed completely. You can modify the side covers by cutting them to fit, but depending on the size of the filter, they may still not work. And the clearance with the battery box, as 5twins stated.
They are held on with clamps.
But not all pods are the same. Some have a lip inside on the rubber throat that will block the air ports on the carbs. Mainly the BS carbs.

And yes, your carbs will need to be rejetted. More air coming in will cause a lean condition, so you'll have to get larger jets.

 

[5twins]

Whether you need to re-jet will depend on a couple of things - the year of the bike/carb set and how many mods in total have been done. The earlier carb sets came jetted richer from the factory. You might get away with not re-jetting if the filter change is your only mod. But, it never hurts to bump the mains up a size to test and make sure.

 

[fredintoon]

Whether you need to re-jet will depend on a couple of things - the year of the bike/carb set and how many mods in total have been done. The earlier carb sets came jetted richer from the factory. You might get away with not re-jetting if the filter change is your only mod. But, it never hurts to bump the mains up a size to test and make sure.

Hi 5twins,
I just swapped my Heritage Special's stock airbox for a pair of UNIpods and never changed nothin'. Mind you, it's a Canadian bike so it ain't as EPA-strangulated as a US model would be.
But I always thought it was the slow-running parts that needed to be opened up more than the mains?

 

[5twins]

Did you use the stubby ones with the rubber or chrome end caps? They don't flow as much air so often don't require a jet change. On the other hand, if you never try the larger main then you'll never know if it's better will you? That's one of the first rules of carb jetting - when you think you're good, try the size above and below where you're at to make sure.

 

[Megatron]

5Twins, this would be the only mod I believe. My bike a 1975 everything is original with the exception of the exhaust.I have slash cut mufflers on it.

 

[5twins]

Well, the different mufflers would be considered a mod as well. Whether or not they flow better or more than the originals is the question. If they do, then it could effect the carb tuning. Your '75 carb set was set up richer from the factory than the newer sets. You may get away with not having to re-jet. Try it stock and see. Watch for lean indicators like surging in the midrange while cruising at a steady speed or lots of popping out the exhausts during decel. If you do need to re-jet, it probably won't take much, something like one or two up on the mains and maybe one up on the pilots.

 

[mohork]

Hi
Is there an easy way of removing the carbs off my 84 xs without taking off the engine intake , or is that the correct way

 

[xjwmx]

^The way I do my '81 is take the tubes and wires loose, then from the left side of the bike pull it out of the holders, then holding it against the backbone tube, tilt the front down a bit and rotate it toward you, keeping it against the backbone. There's just enough room. If you want you can drain the carbs first, or easier just let it run dry first.

 

[5twins]

Well, I wouldn't call it easy but it is possible. You'll need to remove the acorn cover nut on the cam chain adjuster and the throttle cable bracket. Then the carb set can be popped out of the holders and removed out the right side. You'll have to twist and turn the set just right to get it out, but it will come out. It will go back in the same way.

 

[mohork]

Thanks I’ll give it a go

 

[xjwmx]

You'll need to remove the acorn cover nut on the cam chain adjuster

Oops, I left out that step.