[Chiefharlock]

Firstly, let me start off by saying that I love my RE C5 and IMHO couldn't have asked for a better bike as my first bike.

Being a maintenance guy and a bit of a tinkerer, when I get a vehicle I notice things that I would change or improve in the original design after I have racked up some time with it.   The first thing that comes to mind is the air intake set up.  While I understand that some of the reason for eh set up may very well be due to excess intake noise, as is often the case with auto manufacturers.  I have been considering pulling the hose and dropping in a smaller cone style filter and creating a couple of block off plates for the back side of the box so I can utilize it as a tool/equipment box.

Anyone else done this or considered this?

[1 Thump]

The cone type has been tried but for some reason not too popular. There was some talk about how it might affect MAP sensor or some other sensor.

However, you might try this one :

 http://nfieldgear.com/enfield-store/k-n-performance-oem-replacement-air-filter.html

[Chiefharlock]

The primary thing for me would be restoring what was a tool/equipment box to its original use on the older bikes.  So really the K&N to replace the OEM filter wouldn't meet my needs.  Functionality functionality functionality!  I guess that's just my thing.  Thanks for the link/suggestion!

[GlennF]

As stated, might work, but its more likely you will need to remap the injection.

As far as i know that would require replacing the injection computer with one of these:

http://www.hitchcocksmotorcycles.com/news/21975/Dynojet_Power_Commander_for_EFI_Bullets

Warning ... not cheap to buy

Failing that I suppose you could try retrofitting a carby

[prof_stack]

I think the tube from the airbox to the EFI is very important to smooth the airflow coming from the airbox.  I think Ducati Scotty put a cone filter right on the throttle body and reported lower mpg.  He'll fix my errors as needed.

Better would be to enlarge the amount of air that gets into the filter before going through the tube. 

Or just bite the bullet and carefully remap the EFI.

[Ducati Scotty]

I did it.  My MPG dropped from 55 to 45 so I took it off.  With no plenum (the tube between the air filter and the throttle body) there is no chance for the air stream to stabilize and we think the turbulence has a negative effect on the MAP sensor.

I would say the bike felt like it ran just fine and it also felt like there was a light performance increase.  The sound was nothing but glorious.

A K&N filter in the stock air box gives a little more noise, definitely more flow, and maybe performance too without the ill effects on the MAP sensor.  The BM-0400 model kinda fits and they just manufactured a limited run made just for our bikes.

http://www.enfieldmotorcycles.com/forum/index.php/topic,11268.0.html

Scott

[JesterNT]

I tried the K&N Cone and saw a drop in MPG to.  I went back and added an air straightener inside the filter.  I still lost about 2mpg but I attribute this the higher air flow.  I notice the power increase especially when I'm on the highway.  There were some posts on this topic a year or so ago. 

[Ducati Scotty]

Jester!  I don't think you ever chimed back in on the thread you started that took on a life of its own.  Good to know that we both got a drop in MPG and good to know that your original idea for the air straightener seems to have worked.

Thanks for updating us,

Scott

[PAndy]

So overall you only lost 2 mpg by using the flow straightener?

[Chiefharlock]

Okay, interesting feedback... Now here's a question to ponder on.  Does the increased airflow turbulence cause an interference with MAP settings and reduce efficiency due to said turbulence  ---OR---- (food for thought here)  is there an unnoticed subconscious change in driving characteristics by the operator due to the addition of a "performance" air filter.  

[Chiefharlock]

@ Pandy, I believe they lost 2mpg when they switched to just the cone filter instead of the intake tube down to the stock filter location due to the fact that the intake is now pulling air from not only directly in front of the opening but also at a 90 degree angle to the opening creating turbulence in the incoming air stream.   

Honestly, if you ask me, the "air straightener" would just create more restriction across the opening of the intake. and it would be the fact that you are slowing down the over all speed of air coming in that would stabilize the air going into the engine.
 In theory the turbulence that is generated at the opening of the intake is smoothed out as it travels down the intake tube on its way to the throttle body opening.  the real question at this point should be, does it take the entire length of the intake tube to smooth out the intake air or can you shorten that distance and still achieve the same results utilizing a shorter length subsequently freeing up the airbox to be better utilized as a toolbox capable of holding tools and emergency items

[Ducati Scotty]

I have ridden it hard with the stock air filter and get the same MPG as I do putt-putting to work. 

SB said he's seen turbulence from aftermarket air filters mess with MAP sensors before.  I don't know if you'd need the entire length of the stock plenum but you obviously need some.  I think with a little bit of radiator hose you might be able to make it work.

Scott

[Andy]

You just like saying "plenum".   

Very interesting thread so far.  I am learning much.  Mostly I'm learning how little I know about the little things.

[shappers]

Hope this works, otherwise use the search page with conical air filter by shappers

Cheers shappers

[olhogrider]

In the olden days a simple aircleaner, often just a wire mesh screen mounted directly to the carb was deemed good enough. On one of my Ducatis the internet wisdom was to cut holes in the top of the airbox. I did this and got a noticeable increase in power. Much easier to wheelie! It had the unfortunate side effect of destroying the smooth power delivery. It was almost unrideable in corners. The throttle behaved like an on/off switch.

I'm not saying that there will be any great changes if you modify the intake of an RE, just that there is a bunch more science and magic than most of us can imagine. A more open intake can  sound wonderful. That leads me to open it wide more often. For some reason there is a decrease in gas mileage.