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Discussion Starter #1
I was looking for someones stock intake a few weeks ago to play around with an idea I had to modifiy the stock intake but there was no takers.
Well I just spent a good part of the last 3 days modifying mine and here are some of the details.

My criteria was I didn't want to spend $300 dollars for and aftermarket air intake, besides the fact I didn't want to have to worry about rain getting in intake or placing a sock on. I wanted to increase filter surface area, get fresh cool air instead of sucking hot air between cylinders, and I wanted to straighten out the air flow to the throttle body, the stock air flow made 270 deg (3-90's) to get there.

Below are pictures. I was hoping this was a simple job that anyone could do, but the fact of the matter is this modification takes someone with alot of patience and good mechanical and fabrication skills. It may look simple, but this was a extremely tight fit so there was a lot of trial and error fitting. I took 30+ pictures, took notes and saved my templates.

I did take it for a short ride and it seems to have quite a bit more zip to it. I am going on a day long ride tomorrow so I will get a sense of how it performs over a long hall, and can give more details if this thread gets alot of interest.
 

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It has a nice look to it, for sure, breathing right from the side like that. It would be interesting to see the full tale and hear the steps/mods/parts in the process.
 

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It would be interesting to see dyno results too.
 

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its interesting..im just not sure of the snorkel on the side....maybe something with one of the harley covers over the 900 area of the cover....i was tring to come up with something myself with one of the slotted harley covers over it ...i like the straight shot idea though..
 

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Was the purpose of the metal plate just to close off the back side of the filter? What type of round filter element is that? I like the way that looks.
 

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Discussion Starter #7
Well let me start with my trip, I went about 250mi and traveled about 50/50 interstate/local roads. This modification significantly improved the get up and go of idle and roll on. On the interstate traveling about 70-75, I could easly get by semis with just a turn of the throttle passing them quickly at 85-90 (I don't like being anywhere near them). Gas mileage for the trip average about 52 mpg, that's pretty good. I checked the plugs today and they looked good, no indication of running lean. I'm very happy with performance.
There are two downsides, this noise is much more than stock, and I found I had to wear a elastic band around my leg. I found that if your pants are a little baggy and you keep your knees in tight, it will suck your pants material in. I actually had an idea of pointing the opening down but I had this ride planned and didn't have enough time to get done. I should be able to use the existing cover for my upgraded modification.

To answer a few of the questions, first I will be probably give more detail later in the "How To" part of the forum, I have to figure out how much detail and pictures I need first.

Here is a link for a comparable dyno, I'm not going to do one. Just hit the green view button when you get to link page.
http://www.sscycle.com/modules/dyno/index.php?z_catagory=LIKE&x_catagory=4&Submit=Search

The main reason I put the intake where it is, because I didn't want to worry about rain getting in, water won't travel up. I also thought about putting slots around the 900 emblem but it's right above the filter. I know a number of aftermarket filters do that, but I didn't want any chance of water getting in.

I intentionally blocked off the stock airbox, I didn't want to suck in any hot air from between the cylinders, the cooler the air the denser the charge. I even insulated the back of the aluminum with cork because of it's good heat conductivity. I started out with a 6" round straight sided filter similar to what S&S uses. The problem with that is there wasn't much room for air to get to the back side because of tight clearance. Also I found out that wouldn't work anyway because the filter isn't center on the cover circle emblem, it is offset, so it didn't clear the cover. The tappered filter really fixed both of those issues. The filter is a custom K&N filter that I found while looking at their website. I think the taper aids in transitioning the air flow gradually instead of a sharp 90 deg turn into the throttle body. The less turbulent the flow (causes hi pressure drop) the better the air flow into cylinder should be.
 

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Wow. Outstanding job, rs900. It really looks nice and well done. If you have time on your hands, you should consider putting together a package of the parts you made and sell kits. I'm with you, the intake is better below the filter and i like it on the side... just have to make sure not to hug the engine with your legs. : )
 

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I appreciate the work you've put into this, but one comment doesn't fit. If the vacuum sucks your pants into the intake, then surely it will draw water up and into the intake? Or am I missing something?
At any rate, I agree you should market the idea if you do have the spare time and inclination.
 

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Discussion Starter #11
I just installed a cobra FI2000r yesterday (after the 250mi trip). I wasn't going to get one but someone was selling it for $80 on ebay. I called Cobra because I wanted to get some info. The 4 2 0 suggested setting is with Cobra exhaust and aftermarket intake. The tech said that if you set 0 0 0, this would be the stock computer setting. Since the bike ran pretty good without FI2000r I am trying 1 1 0. I want to adjust the factory leaness on the lower end but I didn't want to go to high and start getting worse gas mileage.

Yes, the vacuum could suck alittle water vapor in which shouldn't hurt anything. The vacuum only seemed high during hard accellaration, I didn't notice much with a steady throttle. I'm hoping larger droplets will drop down with gravities help and should end up in the bottom where the exhaust ventilation trap is. The first time after any heavy rain I obviously will be checking that bulb trap to see if my suspicions are right. It has to be better than a BAK or Hypercharger, water is going into those.
 

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Anxiously awaiting the "how to" after all of your testing/evaluation is complete. You, sir, have outdone yourself!! I too love the idea of a better filter, better flow, cooler air without having the open top intake like on a lot of the aftermarket jobs.
 

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Nicely done. Not only does it look great, but it appears to be a cheaper fix than going aftermarket. I rode with a buddy to Sturgis this year and he has a Hypercharger on his bike. Water wouldn't get past his K&N, but the water would clog it up to the point where his bike would just shut down. Not a good thing when you're cruising down the highway. We would have to take his airfilter assembly apart to get to his K&N to shake it out so his bike would start again.

Regardless, I would be interested in your how-to. I can see that becoming very popular.

-PB
 

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Discussion Starter #14
I am in the process of doing a how to modifiy your stock intake for this modification (in "How To" forum). Since I am neither good at writing procedures and adding picture (I'm learning about that now) it is going to take me several parts to complete this series. I will show how to do this so those of you who are mechanically inclined to try can. I am trying to figure out what things I might be able to do to help some of the people that don't have the skills or the tools to do some of these modifications. If you go to the "How To" forum please don't comment in that forum until I have finished the series, so it will look continuous when I'm done. If you have any comments or questions, for now use this thread to do so.

The "How To" may take me several days, since I don't have unlimited free time. The only reason I've been online so much this week is I'm on vacation. Although my wife is getting a little ticked that I'm not getting the honey do list done. So I've got to go out and do some real work this afternoon before she gets home.
 

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BTW, a great way to ensure continuity in a "how-to" thread is to post several times thereafter with a comment "reserved for future development". That way you can practically ensure several posts in a row. :) I learned that from a few gaming forums, as well as some work I've posted in the Mitsu Eclipse forums.

THANK YOU for taking the time to document the process! I'm excited at seeing the full end-result!
 

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Just went to the 'How To' section and looked at your write-up. Looks very good, it's like reading a good book, can't wait to see what's next.
I also have the Cobra FI2000R and have it set to 3-2-0. Don't have an aftermarket intake, just exhaust. This setting seems to help my mileage, I'm getting 55mpg. John
 

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Interesting idea. My Fi2000r is set at 2-1-0 with 60ppi Unifoam airfilter and debaffle. MPG is 50 below 80mph and 46 in traffic. The 900 fuel system is already on the fat side at low rpms so it doesn't need much more.
 

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I have just finished making this mod..I had not thought of completely restricting the "hot" air flow from between the cylinders, but looking at your set up, realized it was very easy to do and would not be cost restrictive. This is very easy to do if you understand the dynamics and and have the various tools to do it. I didn't have access to the type of filter you used so I used a 6 1/2 x 1 1/2 paper filter and installed it. One thing I did do different, was to allow more air flow from the cover than you did. Basically removing the two side portions of the upper cover in an elliptical shape and symmetrically removing the lower portion of where you have the intake. About four or five times the "open' area. I haven't any pics as yet, so I think you may want to "ad lib" as to what I fashioned. One thing I did notice right of the bat was the mid throttle response at about 100 to 120 kph. I think it is safe to say that the amount of flow will be dictated by the type of air filter you use, with K&N being the better of the lot. I haven't read the plugs, but judging from what I did read with my initial set up , there really is no problem, unless of course hard roll on and competition is what's in your mind.........Does seem to work very well as fabricated... Nice job over all and very cheap as well....Kudos for the effort and fine job!!
 

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Discussion Starter #19
K&N Part# E-9156

thewazard, thanks for the complement.

I probably should of gave the filter information up front for anyone that wants to do this and doesn't need my "How To" thread. The filter isn't cheap, it's about $50, but I really thought the tappered shape was beneficial to what I wanted to do. If I found a cheap paper one that shape, I may have used that. One thing I learned from experience and research, is that when you get higher flow filter elements, you are loosing some of the filtering efficiency. To get more flow, you need less restriction (larger opening in element), which also means not as good of filtering. So one way to get better flow without loosing filtering efficiency is increase the surface area. Anyway I couldn't find a tappered paper one that fit, and I've used K&N for years and can't say I've ever had a problem. Besides you''ll never have to buy a filter again.

Here's a little more info on my choice of filter element shape. Originally I was going to use a straight sided filter, I bought a 6" x 2" fliter for $7. The only reason I decided not to use it was there wasn't alot of room around the sides for the air to get to the upper part of the filter. Also I found that the straight filter was hitting one side of the cover after I made my mounting bolt on the plate, the filter wasn't centered on the circle emblem in cover that happens to be 6" also. Here's a picture with the filter centered, you can see if it moves off center it will be hitting the tapper transition and the filter will be higher than the cover. I think yours worked because you used a 1-1/2" high filter.



Here's the K&N in the cover, there is alot more room for the air to get to the back side.



I started doing this project about 3 days before a planned trip, so I didn't complete the cover the way I planned. (it's going to get done this winter). Anyway the intake size I don't think is as much of a problem as the location, the turns the air makes and filter element surface area of the stock intake. The opening of the rubber intake is about equal to the throttle body opening with a nice straight path so I doubt that opening up the area will make a whole bunch of difference.

Did you use any of my "How To" thread or did you just use the concept and pictures from this thread and go from there? I was wondering if anyone looked at the "How To" and thought it is useful. I wasn't sure how detailed to be, I am sure there is a mixture of fabrication experience from machinist to someone that isn't very handy with tools. I am almost finished, should I complete this thread with the same detail I am using or not show so many pictures and explanation?

I am back to work and I am in competition for computer time after work, I have 3 daughters in high school that always need it for homework, so I probably won't be doing much more until the weekend, I'd be interested in any comments from previous paragraph.
 

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I did have a look at your method, and saw that initially it wasn't much different than what I had in mind to do.....The main difference was the closing off the hot air flow. What you had done essentially avoids "the big sucker" backing plate and rerouting of the vent hoses and such. The concept is a cheap answer to an otherwise relatively expensive mod. I also had the same problem with air filter selection.. The K & N filter was one of choice but, unfortunately not available and about $10 or $15 more than your cost. The paper element was even difficult to get, believe it or not, and I had to settle for a "conversion kit" that had cover, plenum and threaded rod, so for the $20 I spent I managed to get the other parts I needed. The lower profile filter allowed some movement and the filter is off set somewhat, but does not cover the intake of the throttle body. The backing plate intake opening was made a bit smaller than yours and the rubber goose neck was used as gasket. That allowed me to use three of the cap screws to secure the air box to the throttle body without problems. Of course this manner depends on the gauge of plate used to close off the hot air flow. When I get some pictures I'll post them so there can be a comparison of how this went together.. The difference in the modification as well, was the intake cover. While your's is set up with a low opening, I have mine cut to allow air flow directly in at each side and at the bottom. I placed a light gauge speaker grill over each of the cut outs inside to make it look a bit better and keep out debris. So there you have it......same thing only different....
 
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