opinions - Uni filter with "almost" stock jetting.

Last night, I was reading through all the different conversations about air filters, paper vs. Uni vs K&N. Lots of varied opinions.

On my bike, a previous owner added the Uni filter, glued in place of the paper filters.

My original intention was to go back to the paper filter, so I stayed (mostly) stock, with #41 jets -- stock is #40--so I wouldn't be as lean as the factory made it. I left the main jet at #120.

Question one: the jetting. I saw several people claiming that the Uni filters worked fine with their stock jetting. I was under the impression I should go up to this: pilot jet = #42 and main jet = #124.

Question two: assuming the answer might be "paper"... What to do? What to do! Should I just tear out the foam and drop in the paper, or keep that as an extra, in case I get bored and up the jets, then get a whole new frame to drop the paper into. (can I even 'cleanly' tear out the foam?)

 

Ask yourself this. How willing are you to remove the whole damned airbox when that UNI filter needs to be cleaned?

Cut the foam out, scrape the glue off, and put a paper filter in.
How to best remove the glue will depend on what glue was used. The paper filter has a foam seal, and is squished into place by the airbox lid, so the mating surface of the airbox does not have to be perfectly smooth.

If you really want a foam filter (honestly they filter less dust and crud out than paper filters do), both UNI and K&N make drop in filters for the stock aitrbox. I've got one of the K&N foam filters sitting on my shelf.

 

Good point, good point. A little work scraping glue now, so that I don't have to deal with the airbox later. I'm leaning that direction, for sure.

 

I have had a direct fit UNI filter in my bike for years now. Clean it once a season, at most, and have zero issues with it.
Slides in and out just as easy as the stock paper filter but never needs replacement.

 

here's what i did with uin foam, and a MAC 4/1 pipe with the megaphone muffler and a Supertrapp muffler.
wrapped the stock filter frame with a layer of fine foam then a layer of coarse foam (mac with megaphone 40,120)....way lean
same setup with 124, 40....rich with serious bog at 5k
same setup with 122, 40....not bad but the 5k bog is still there
threw out the megaphone
enter the supertrapp, started over with 8 plates in the muffler
found happiness at 122, 40, 4 plates in muffler, this only took about a month of messing around
so, if you change the gozina you got to change the gozouta or get lucky
just get a paper filter and go for a ride

 

Sounds like perhaps you don't have any other performance issues. If you did (like I did initially) it's best to go back to "square one." Dig out that aftermarket filter and put a stock (paper) filter back in so you can rule that out as a potential problem.

I had all kinds of issues when I first got the 700. I too found a red UNI filter in my air box. I pulled it out and replaced with stock as part of my problem finding initiatives.

After all that was done, she runs great now. Was it my air filter? Maybe.. but honestly, I don't care!

I found the UNI filter good for getting the crud off the barbecue grill.

 

Yep, I'm goin with the standards! Len's probably stuffin' my new paper filter in with some other goodies to ship right about now.

 

K&N don't make foam filters, they make cotton filters that must be oiled to work. You may be able to buy foam covers that say k&N on them, to catch the big bits....

 

Whatever they are made of, they make a stock XJ run lean.

 

Agreed on that one kmoe.