Drilled a hole in my cover to run a K&N filter (pics)

[PapaWhitebeard]

I know not everyone loves K&N filters but I’m a big fan of them.

Bottom line up front: I’m really happy with this mod. It clearly pulls loads more air in and the saw is breathing better, winding up faster and I wish I could put it on a dyno to see if the torque increase is in my head.

But for certain it’s pulling more air in… so much so that when I tested it without wearing gloves (or a bar or chain on it) I could feel the air sucking, rushing into the intake. Much more than with the unifilter or the mini fake K&N filters I got off amazon that are 2 for 10 bucks

Whether you’re a fan of K&N filters or not, there’s no arguing that a larger filter pod than OEM will let more air into your intake.

I was using a foam unifilter—and those work *GREAT* but just because of the pod volume alone this K&N is an improvement.

Yes I had to drill a 2.5” hole in my cover to get the cover to fit over this silly filter… I realize this isn’t some super high compression hotsaw with a velocity stack and a long exhaust pipe getting all that scavenging advantage (I love those BTW)… all the same this K&N is *working*








I used the oil/debris marks left from the unifilter to find the exact center point for the filter before drilling out with a hole saw (note that the filter doesn’t sit in the exact center of the back cover so for anyone trying this at home I’d advise against simply measuring dead center or the back cover). After indexing the mark with a compass and the diameter I’d need where it exits the cover… I took a breathe and drilly drill drilled!

Yep it sticks out. Yep it’s ugly. But FWIW I don’t even notice it’s on there because it doesn’t interfere with my grip at all like the giant 6 inch K&N filters that will fit with this intake manifold diameter (which is 57mm BTW on a 462CM)

Those inexpensive fake k&N’s work fine but they’re tiny and don’t have the surface area to get high CFM and they get clogged up pretty quick. But they’re only 5 bucks each (shrug) and you don’t have to drill any holes in the cover

Pics of the knock of $5 fake K&N (they fit under the cover BTW)



Sure there are more and better ways to improve this particular saw but for “everyday use” this is proving very usable and is making a difference and I’m happy with it.

I could do more for sure more—but it’s still in its warranty period and if something goes wrong I’ll slap an OEM cover, air filter and exhaust back on it so I don’t get denied any warranty claim I might need it make (fingers crossed I won’t need to). After the warrant period is over I’ll decide if I want to go for full-on porting and polishing etc.

Other than the ugly hole in the cover (which personally doesn’t bother me) this was a very simple modification. K&N Part # of the filter in the pic below for anyone interested. Note that this filter has a flange ID of 55mm so it’s a tight fit… 57mm is the OD of the intake if you’re looking at other K&N filters to try I use 57mm or 58mm ID flanges if I have a choice.

Hope this is useful or at the very least amusing for some of you folks out there in interweb land

 

[Bob Hedgecutter]

You are a sinner and shall burn in hell for all eternity.
Love it- your saw your choices.

 

[PapaWhitebeard]

You are a sinner and shall burn in hell for all eternity.
Love it- your saw your choices.

Thanks, fella!

 

[Old2stroke]

View attachment 1207485



View attachment 1207487

I know not everyone loves K&N filters but I’m a big fan of them.

Bottom line up front: I’m really happy with this mod. It clearly pulls loads more air in and the saw is breathing better, winding up faster and I wish I could put it on a dyno to see if the torque increase is in my head.

But for certain it’s pulling more air in… so much so that when I tested it without wearing gloves (or a bar or chain on it) I could feel the air sucking, rushing into the intake. Much more than with the unifilter or the mini fake K&N filters I got off amazon that are 2 for 10 bucks

Whether you’re a fan of K&N filters or not, there’s no arguing that a larger filter pod than OEM will let more air into your intake.

I was using a foam unifilter—and those work *GREAT* but just because of the pod volume alone this K&N is an improvement.

Yes I had to drill a 2.5” hole in my cover to get the cover to fit over this silly filter… I realize this isn’t some super high compression hotsaw with a velocity stack and a long exhaust pipe getting all that scavenging advantage (I love those BTW)… all the same this K&N is *working*


View attachment 1207482



View attachment 1207483

I used the oil/debris marks left from the unifilter to find the exact center point for the filter before drilling out with a hole saw (note that the filter doesn’t sit in the exact center of the back cover so for anyone trying this at home I’d advise against simply measuring dead center or the back cover). After indexing the mark with a compass and the diameter I’d need where it exits the cover… I took a breathe and drilly drill drilled!

Yep it sticks out. Yep it’s ugly. But FWIW I don’t even notice it’s on there because it doesn’t interfere with my grip at all like the giant 6 inch K&N filters that will fit with this intake manifold diameter (which is 57mm BTW on a 462CM)

Those inexpensive fake k&N’s work fine but they’re tiny and don’t have the surface area to get high CFM and they get clogged up pretty quick. But they’re only 5 bucks each (shrug) and you don’t have to drill any holes in the cover

Pics of the knock of $5 fake K&N (they fit under the cover BTW)

View attachment 1207486

Sure there are more and better ways to improve this particular saw but for “everyday use” this is proving very usable and is making a difference and I’m happy with it.

I could do more for sure more—but it’s still in its warranty period and if something goes wrong I’ll slap an OEM cover, air filter and exhaust back on it so I don’t get denied any warranty claim I might need it make (fingers crossed I won’t need to). After the warrant period is over I’ll decide if I want to go for full-on porting and polishing etc.

Other than the ugly hole in the cover (which personally doesn’t bother me) this was a very simple modification. K&N Part # of the filter in the pic below for anyone interested. Note that this filter has a flange ID of 55mm so it’s a tight fit… 57mm is the OD of the intake if you’re looking at other K&N filters to try I use 57mm or 58mm ID flanges if I have a choice.

Hope this is useful or at the very least amusing for some of you folks out there in interweb land



View attachment 1207484

View attachment 1207485



View attachment 1207487

I know not everyone loves K&N filters but I’m a big fan of them.

Bottom line up front: I’m really happy with this mod. It clearly pulls loads more air in and the saw is breathing better, winding up faster and I wish I could put it on a dyno to see if the torque increase is in my head.

But for certain it’s pulling more air in… so much so that when I tested it without wearing gloves (or a bar or chain on it) I could feel the air sucking, rushing into the intake. Much more than with the unifilter or the mini fake K&N filters I got off amazon that are 2 for 10 bucks

Whether you’re a fan of K&N filters or not, there’s no arguing that a larger filter pod than OEM will let more air into your intake.

I was using a foam unifilter—and those work *GREAT* but just because of the pod volume alone this K&N is an improvement.

Yes I had to drill a 2.5” hole in my cover to get the cover to fit over this silly filter… I realize this isn’t some super high compression hotsaw with a velocity stack and a long exhaust pipe getting all that scavenging advantage (I love those BTW)… all the same this K&N is *working*


View attachment 1207482



View attachment 1207483

I used the oil/debris marks left from the unifilter to find the exact center point for the filter before drilling out with a hole saw (note that the filter doesn’t sit in the exact center of the back cover so for anyone trying this at home I’d advise against simply measuring dead center or the back cover). After indexing the mark with a compass and the diameter I’d need where it exits the cover… I took a breathe and drilly drill drilled!

Yep it sticks out. Yep it’s ugly. But FWIW I don’t even notice it’s on there because it doesn’t interfere with my grip at all like the giant 6 inch K&N filters that will fit with this intake manifold diameter (which is 57mm BTW on a 462CM)

Those inexpensive fake k&N’s work fine but they’re tiny and don’t have the surface area to get high CFM and they get clogged up pretty quick. But they’re only 5 bucks each (shrug) and you don’t have to drill any holes in the cover

Pics of the knock of $5 fake K&N (they fit under the cover BTW)

View attachment 1207486

Sure there are more and better ways to improve this particular saw but for “everyday use” this is proving very usable and is making a difference and I’m happy with it.

I could do more for sure more—but it’s still in its warranty period and if something goes wrong I’ll slap an OEM cover, air filter and exhaust back on it so I don’t get denied any warranty claim I might need it make (fingers crossed I won’t need to). After the warrant period is over I’ll decide if I want to go for full-on porting and polishing etc.

Other than the ugly hole in the cover (which personally doesn’t bother me) this was a very simple modification. K&N Part # of the filter in the pic below for anyone interested. Note that this filter has a flange ID of 55mm so it’s a tight fit… 57mm is the OD of the intake if you’re looking at other K&N filters to try I use 57mm or 58mm ID flanges if I have a choice.

Hope this is useful or at the very least amusing for some of you folks out there in interweb land



View attachment 1207484

Love the K&N filters, used them on all my ‘vettes

 

[PapaWhitebeard]

Love the K&N filters, used them on all my ‘vettes

Thanks, old2stroke… I run them in everything that has a motor. They work… depending on how restrictive the factory intake is, they can make an enormous difference…

With a handle like that you might be a dirtbike guy… on my mid-2000’s KTM supermotos (basically dirtbikes with street rubber on them) from back when you could still hack fuel and timing maps with a laptop, tuneECU and a cable I’d chop the airbox off completely, crank open up the AFM put a giant K&N pod on it, advance the timing and tweak the fuel maps with an o2 sniffer and man oh man did those bikes come alive. The sound of the intake when you went WOT was almost as loud as the exhaust

 

[ballisticdoughnut]

Got a K&N on a couple of my saws. Can’t see them directly but they’re in there.

 

[Bob Hedgecutter]

Got one of my 2100's needs an air filter- if I want to run it- I borrow a flat filter off of one of the other 3, but been daydreaming about podding it- cant bring myself to butcher the filter cover- but it looks just "odd" to run with an open air box.

 

[ballisticdoughnut]

Got one of my 2100's needs an air filter- if I want to run it- I borrow a flat filter off of one of the other 3, but been daydreaming about podding it- cant bring myself to butcher the filter cover- but it looks just "odd" to run with an open air box.

Yeah I just can’t butcher a top cover for a pod filter unless I had another OEM one on hand. No way I’d do it to an old school husky those covers are hard to find. Even then I’d be very hesitant.

 

[PapaWhitebeard]

Got one of my 2100's needs an air filter- if I want to run it- I borrow a flat filter off of one of the other 3, but been daydreaming about podding it- cant bring myself to butcher the filter cover- but it looks just "odd" to run with an open air box.

Agreed which is why I bought a spare cover from a guy who was parting his saw out before I started going all Frankenstein on mine

Idk if your filter is a box style like ballisticdonut’s or a round bottom style filter like mine but if you have an open bottom box style like his there are loads and loads of K&N filters that will fit without needing to butcher anything. If you go on K&N’s website you can enter basically ANY criteria… size shape height width tapered square rectangle whatever and it will tell you what filters fit. Good luck!

(And I agree not to chop up your cover if you can avoid it)

 

[PapaWhitebeard]

Got a K&N on a couple of my saws. Can’t see them directly but they’re in there. View attachment 1207510
View attachment 1207508View attachment 1207509

Love those old husky’s. I raced husqvarna dirt bikes for awhile… love those too

And agreed *definitely* don’t butcher those saws

 

[NSEric]

I run my saws in the rain and snow some times so I cant drill a big hole in the cover and run a pod filter.
If you never have to deal with bad weather I'm sure they add a little power and keep all the dirt out.

 

[bwalker]

You did a good job drilling that hole.
FWIW I always prefer a oiled foam filter over a K&N.

 

[PapaWhitebeard]

I run my saws in the rain and snow some times so I cant drill a big hole in the cover and run a pod filter.
If you never have to deal with bad weather I'm sure they add a little power and keep all the dirt out.

FYI those outwear filter covers are waterproof. But you’re right you don’t want cold water getting on a hot motor!!

 

[PapaWhitebeard]

You did a good job drilling that hole.
FWIW I always prefer a oiled foam filter over a K&N.

Thanks (grin) I drilled a hole once before (shrug)

But I respect your thoughts and opinions curious why you prefer the oiled foam? I use oiled foam filters in all my KTM dirtbikes and they work fantastic. They just require service really often… which is fine because KTM gave me piles of them and I just swap them out. And wash and re oil them in batches…

 

[bwalker]

Thanks (grin) I drilled a hole once before (shrug)

But I respect your thoughts and opinions curious why you prefer the oiled foam? I use oiled foam filters in all my KTM dirtbikes and they work fantastic. They just require service really often… which is fine because KTM gave me piles of them and I just swap them out. And wash and re oil them in batches…

Mostly because I had a Chevy truck that showed hi silica numbers in it's oil after running a K&N. Did some digging and found this wasn't uncommon with K&N's. In my dirtbike days I always used oiled phone and never had an issue. I also grew up riding in an area where the dirt was like Glamis dunes!

 

[PapaWhitebeard]

Mostly because I had a Chevy truck that showed hi silica numbers in it's oil after running a K&N. Did some digging and found this wasn't uncommon with K&N's. In my dirtbike days I always used oiled phone and never had an issue. I also grew up riding in an area where the dirt was like Glamis dunes!

Yeah I’ll be sure to watch for that. In a 2-smoke I’m not worried about it but for anything with a sump I’ll be checking because I’m curious.

In non-race cars I change oil every 5k miles. In motorcycles racing or not I tend to change oil far more often depending on the bike because I absolutely beat on them so I baby them on maintenance front. Have a 821cc twin with 48k miles mostly at WOT but I’ll be checking that sump first. Needs valves adjusted every ~8k miles but not by much and compression in both cylinders match and only ~10% lower than it was at 500 miles.

But thanks for the data. Im gonna be checking silica content in oil next weekend

Because silica is either because the filter isn’t getting serviced enough or because even with proper service bits o sand are sneaking through there…

FWIW I’ve noticed the thick red K&N oil filters better than their spray-on oil. Like… a lot better. But I’m gonna check it out.

Thanks dood.

Always stuff to learn right?

 

[bwalker]

Yeah I’ll be sure to watch for that. In a 2-smoke I’m not worried about it but for anything with a sump I’ll be checking because I’m curious.

In non-race cars I change oil every 5k miles. In motorcycles racing or not I tend to change oil far more often depending on the bike because I absolutely beat on them so I baby them on maintenance front. Have a 821cc twin with 48k miles mostly at WOT but I’ll be checking that sump first. Needs valves adjusted every ~8k miles but not by much and compression in both cylinders match and only ~10% lower than it was at 500 miles.

But thanks for the data. Im gonna be checking silica content in oil next weekend

Because silica is either because the filter isn’t getting serviced enough or because even with proper service bits o sand are sneaking through there…

FWIW I’ve noticed the thick red K&N oil filters better than their spray-on oil. Like… a lot better. But I’m gonna check it out.

Thanks dood.

Always stuff to learn right?

Another poster said that K&N changed their filter media in the recent past, so maybe they are better.

 

[PapaWhitebeard]

Another poster said that K&N changed their filter media in the recent past, so maybe they are better.

Yeah idk… I been using them since the 90s but I always like data. So I’ll be investigating

The fact is servicing them properly is a medium pain in the azz… I use bottles like this one and have to drizzle the red goo onto each little fold… wait 20 minutes and rotate the pod to the next section… repeat… etc.



And like I said the spray on stuff goes on easy but simply don’t filter anywhere near as much material as the thick goo.

So I suspect a lot of users are buying the pre—oiled filters, installing them and never touching them again… and some are servicing them but doing it wrong… using a high pressure nozzle to wash them out (which destroys them) or whatever.

So they aren’t the most user friendly filter that’s for sure.

Unlike the foam unifilters which are super easy to service.

But I care about my vehicles so I’m going to be dumping oil through a 25 micron screen to see if any sand is in it. Then I’ll dump it through a 10 micron which takes all day… but like I said… I’m curious.

So… thanks fella

 

[NSEric]

FYI those outwear filter covers are waterproof. But you’re right you don’t want cold water getting on a hot motor!!

They are not waterproof.
Funny story, I had a K@N filter on my race quad and noticed water getting into it so I called K@N. They claim the outerwears are water resistant not water proof. I went back to foam filters.
If you leave the saw out in the rain, the filter will be wet and the saw will run like poo.
It's your saw do whatever you like to it but work saws have the air filter under the cover for a reason.

 

[Mad Professor]

I run my saws in the rain and snow some times so I cant drill a big hole in the cover and run a pod filter.
If you never have to deal with bad weather I'm sure they add a little power and keep all the dirt out.

OEM?