2.25" and 2.375" big deep oval K&N for old football and oval CVO covers.

[dave brode]

Anyone used one of these?

https://www.knfilters.com/search/product.aspx?prod=RK-3910-1

Looks like it'd flow better than the typical round filters. Oddly, they only offer the 2.25" in the older "carb" bolt pattern. Others are 1.625" thick.

Thinner filter in the newest efi bolt pattern.
https://www.knfilters.com/search/product.aspx?prod=RK-3930

Getting separate external breather lines out might prove to be a challenge.

--

This one has a 2.375" deep element [takes the "ventilator" CVO covers too, maybe a stock one with the top/bottom wings cut off].
Looks to be easy to plumb external lines. No carb'd pattern offered though.
https://www.knfilters.com/search/product.aspx?prod=RK-3952S

Here's  thread to a ventilator cover on it on an M8.
https://www.cvoharley.com/smf/index.php?topic=117074.0

Dave

[dave brode]

Beware the older 3910 and 3910-1 football cover versions with flat back plate, custom stand-offs that protrude into a filter element that has req'd cut-outs. This earlier version is plentiful on ebay.

[itsafatboy]

I like these the extended depth one still tapered so fits cover nice

http://www.exotx.com/filters.htm

[speedzter]

I had the older version fitted to a 113/mikuni setup for a while.
I modified the standoff's for external venting, easier with the early version, and made it easy
to remove the filter assembly to work on the Carby.
The internal rubber bell mouth is a bit flimsy, and doesn't fit that well.

Not a good shot, but you get the idea (you can see the Mikuni adapter):

[attach=0,msg1276445] 

[dave brode]

Yes, I see what you mean on the stand off bolts being simpler. I bought a newer style yesterday for $100 shipped NIB, so I'll have to make it work.

[dave brode]

The newer style will be easy to vent externally. The element has rubber tits that block the passage from the heads [see pic]. The normal passages, which lead to the carb/TB throat, would be plugged, and the casting passages to the head could be drilled and tapped for fittings outboard of the head at the desired angle/location.

https://www.knfilters.com/search/product.aspx?prod=E-3985

https://www.knfilters.com/images/l/RK-3930X_Alt.jpg

https://static.summitracing.com/global/images/instructions/knn-rk-3942.pdf

Dave

[dave brode]

More FWIW

This kit has a filter element listed as 3.375" thick. I ordered the element, just to see.

https://www.knfilters.com/search/product.aspx?prod=E-3985

https://www.knfilters.com/search/product.aspx?prod=RK-3930X

---

2.188" thick
https://www.knfilters.com/search/product.aspx?prod=RK-3910-1

Other similar kits
https://www.knfilters.com/harley_custom.htm?pkid=6334806&rw=1

Also
RK-
3956
3953
3942

Dave

[speedzter]

That is a large filter, at 3.375" it should flow !
I'm sure the one I used was only around 2.25"

Is the back-plate Aluminium ?, or plastic as it looks like in the pics ?

[dave brode]

Backing plate is powder coated cast alum. Similar to the cast oval one on the 110 CVO bikes.

I will believe 3.375" when I see it.

Filters in various other new style kits are listed as 1.625" and 2.188". The spacers for those are 1.50", and 2", respectively. The spacers listed for the RG-3930X kit are 2.5". That "should" make the filter 2.688", which isn't bad.

[trex]

I like these the extended depth one still tapered so fits cover nice

http://www.exotx.com/filters.htm

I like em too. been using them for years, glad I saw your comment as I was going to suggest a look at Exotx

[ThumperDeuce]

I like these the extended depth one still tapered so fits cover nice

http://www.exotx.com/filters.htm

I like em too. been using them for years, glad I saw your comment as I was going to suggest a look at Exotx

[dave brode]

https://www.knfilters.com/search/product.aspx?prod=E-3985

The E-3985 filter element [from the RK-3930X kit] is 2.625" thick, vs 2.188" or 1.625" for the smaller two elements used in other kits.

They incorrectly list it as 3.375" [which it does measure including the ring]. I even called and asked it the 3.375" dimension included the ring.....

Still, at 2.625", it looks to me like it should flow well. I see no rhyme nor reason why there are three different width elements in these similar kits. They all accept the football cover, afaik. The 3930X kit has the later efi pattern...

Dave
 

[dave brode]

This is the smaller filter, just showing these to illustrate how the nubs close off the passage from the heads. The longer stand off were $1 ish each. i