FE/FC FE Air box Mod and K&N install.

After installing a new K&N air filter with the optional K&N pre-filter I could not help myself and felt the need to modify my airbox to open it up for more intake volume and increased flow to that new awesome filter. I could not get myself to drill a bunch of large holes in the side of the left air box I always thought this looked extremely tacky-land would leave the air filter unprotected from Roosts, water, branches Etc... After a couple cups of coffee one morning I came up with this. I removed the left side air box cover and drew a line with a sharpie marker from about 25 mm from the top front corner too 0 along the top approximately where the cover meets the rear top corner of the actual air box. I cut this portion off with a reciprocating saw. I'm really happy with the way it turned out. You have to look close to see the difference from the stock cover or even notice it's modified by looking. It looks great and really made a big difference in throttle response. I'm guessing this mod is equal to about 5 25mm holes. I'm also very happy with the K&N air filter. It seals against the airbox much better than even a properly greased stock Twin Air. No dust or dirt has passed the air box seal in over a hundred miles of use. The new filter even came with a tube of seal Grease. Yes iucu has been retuned for the increased intake volume and the stock air filter is on its way to a land fill.

Did you modify both sides for more air ?

Yes I did modify both side panels however after some experimentation I realized that the mod that I did to the left side air panel was more than sufficient even though I had actually started cutting on the right side side panel first. Most noteworthy is that I have recently swapped out my stock fuel rail with an aftermarket fuel rail from Dave Simon at best dual sport bikes. Com The fuel rail combined with an after-market exhaust end cap and a throttle position sensor reset of .66 volts has made this bike absolutely ferocious. I am now ripping 4th gear roll on wheelies over 50 miles an hour with no clutch and stock 15/45 gearing. I know there are a lot of TPS tuner haters here Sorry I'm not one of them. I've done my research. I've tuned my own bike and now it flat rips!

I know there are a lot of K&N air filter haters here. I would like to say that I just attended an AMA Grand National Championship flat track event. "DIRT." The Sacramento mile. K&N air filters were so prevalent ob every bike They were almost like toilet paper in the restroom. Almost every bike had one. I'm sorry if you've ever had bad luck with K&N air filters. If you would please take note you will see that I am running a K&N pre-filter this is a poly woven microfiber material that has a very fine micron Mesh. I have over a thousand miles on this setup now with no problems every couple of rides I pull the filter and wipe up the air intake boot with a paper towel to check for micro fine dust particles or any other contaminant that may have passed give the filter or the filter air box sealing surface so far this filter combination has worked flawlessly! I attributed this filter combination success to proper maintenance and installation having strictly followed K&Ns installation and maintenance instructions. One thing I have noticed is that a lot of people that are running K&N filters are not maintaining them properly. I've noticed people clean their air filters with an air compressor not following K&Ns Instructions This will cause you to blow holes into the gauze material that will allow dust to pass through the filter. Other people are not oiling them enough I'm even worse others are expecting them to last 20 years or more. If you hold a brand new K&N air filter up to the light there are not visible holes This is because the guaze is carefully layered in multiple layers to create a filter that when properly oiled, cleaned, maintained will not pass dirt... It's when people improperly clean, maintain any filter that they compromise them. Regardless the addition of the pre filter that is available for the K&N on these KTMs and Husqvarnas prevents most filter problems known to these bikes and makes them pretty much idiot-proof. I have proven my bike is not passing even micro fine dust particles. I have proven this by using a perfectly clean paper towel to wipe the air intake boot after every few rides! No dirt no dust nothing but clean air.

Great info. I have the 15 FE 501 and want to unleash its potential without wasting money.
With a 15/45 sprocket combo how does it cruise at 60mph on the hiway?

With the stock 15/45 gearing it's really perfect for the highway and even a lot of off-road situations. At 60 mph it will happily Cruise in either 5th or 6th Gear your choice depending on how much roll on you want at any given moment. At 60 miles per hour you can easily drop to 4th gear and pass most cars and even some bikes like a madman. I love Sneakin up on Harleys and roasting them. I am currently running a 46 tooth supersprox rear from KTM hard parts. I have some mixed feelings about the slightly lower gearing.Yes the throttle response is a little more on tap in some gears however the lower gearing is creating excess wheelspin and negatively affecting my acceleration in first through 4th gear off road. My experience with open Classic Bikes has proved that the taller the gearing the better for reducing wheel spin also makes your bike much easier to get going in deep sand. I experience longer bursts of acceleration and ultimately my bike is quicker with taller gearing. Also moving the axle forward slightly for the one tooth larger sprocket made the rear of the bike want to wash out while drifting under throttle especially on hard pack or loose ground. The more time I spend on this like the more I realize the stock gearing is really perfectly matched to the bikes power however you will find yourself going very fast in situations you may not realize how fast you are going. Whacking the throttle open in fourth can take you to over 75 miles an hour real quick. I highly recommend a trip to best dual sport bikes website. Their exhaust end cap and TPS tuner combined was the best money I've spent on my bike yet. The power and throttle response gains were huge for the amount of money spent. Start with a TPS output voltage of .64 - .66 with the opened up exhaust. I know there are people here that will say this is a waste of time and you should get a Euro remap and a full FMF exhaust system etc. Some of these people are right especially if you don't mind spending about 7 times what the best dual sport bikes setup will cost you. David Simon has done a lot of research as well as I have. These simple mods are fine 4 dual sport / off-road enthusiasts not needing or wishing to build the most expensive or fastest bike possible.

David Simon is a snake oil salesman.

Lol that's funny. It is sad when an information Forum turns into a peeing contest. I am here to learn and to share my experiences I am wide open to any intelligent input and conversation. I don't believe this is a place for any kind of insults or personal attacks. I permanently left thumpertalk and will not go back for similar reasons.There was too much ignorance over there. Too many people who clearly do not ride their bikes or possibly don't even own bikes engaging in the forums and insulting people's intelligence. Throttle on! I am now going to suit up and put over 200 miles on my bike today in the rain. Yes it's raining in Willits California

Your airbox mod looks good.... I wouldn't use a K&N here on the East Coast but that's just me..... but the mod looks good....

Same here in socal, I have K N's in my vehicles, but never my dirt bikes. Foam is thick and gives a tough path for silt to get past, kns mesh gauze is pretty thin, once its past the first layer, its in. Dont read too much into what the grand nationals run, they only care about HP and not the engine lasting 10k miles. They get pulled down and refreshed way more often than we hope to not having to do. Cool mod though and I'd like to see how the Kn holds up over time

I did the mods Throttle On recommended. I cut the air box along the top of the left side panel,installed the Best Dual Sports end cap and set the tps to .66. I still use the stock filter.
Very noticeable improvement in throttle response. The motor is very snappy and still pulls forever. The only small negative is that it now has more engine breaking than it did before.
Bottom line is that there was a nice improvement over stock for less than $200

Do you oil the filter skin in the KTM system?

I wouldn't run a K&N on anything including the street driven vehicles even if they were given to me free of charge. Their own data shows that they aren't good filters but to be fair they do flow slightly more air... (because they have bigger holes in them! )

Nice airbox mod. Clean and much better looking than holes. Personally, I had mine remapped, and added a open end cap. Ultimately, I went back to the stock end cap with the little screen in the end removed. I felt the open end cap didn't do much for power and mostly just made more noise.

I still think you guys are not installing or maintaining your K&Nsproperly If you're not happy with them. They seem to work in the Baja silt just fine. With my set up I never find even the finest dust particles passing the air filter. I wipe out my airbox with a paper towel-daily after every ride! This might just be the difference between me and a whole Lotta other dirtbike riders. I actually maintain my air filter daily like we are supposed to.

Excuse the typo You are obviously still installing and maintaining your K&N filters IMPROPERLY ! They do come with instructions. Any off road motorcycle owners manual that I have read in the last 30 years has spelled out specifically that you must maintain your air filter properly after every ride! This is where I think a lot of riders are screwing up. They are expecting too much out of their air filters. They are not properly greasing the filter airbox mating surface. In the case of K&Ns too many people are making the mistake of using Air compressors to blow their filters out. This destroys the K&N air filter. Even after riding in Nevada, California,Oregon, Baja sand and silt I have seen no microfine dust particles pass my K&N air filter set up. I can't say it enough times I wipe out the inside of my airbox after every ride with a paper towel. I use the Kleenex brand Viva paper towels. I love them. Over 5000 miles on my FE 501s with this set up and no dust dirt or micro fine dust particles present in my airbox