Airbox decapitation how-to....


Page 1 of 18 12311 ... LastLast
Results 1 to 10 of 174

Thread: Airbox decapitation how-to....

  1. #1
    Bassdude404's Avatar
    Bassdude404 is offline The guitar, not the fish!
    Ohio Riders Group
    Michigan Riders Group
    Indiana Riders Group
    Illinois Riders Group
    Join Date
    Sep 2007
    Location
    Rolling Prairie, Indiana
    Age
    52
    Posts
    33,366
    Post Thanks / Like

    Exclamation Airbox decapitation how-to....

    Seems like every week I get at least one (usually more) PM's asking me about how I did the decapitation mod to my factory airbox...While I have no problems with helping my fellow Xr's, I keep repeating the same info over and over and over and, well you get the idea....So I decided to just take the time to post up a how-to that anybody can reference...By doing this you gain two positives...First is the additional airflow over totally stock..The factory setup is pretty restrictive and chopping the top off completely opens up the top of the airbox, allowing it to flow ALOT more air...Second if it's done the way I did, you can from this point forward, remove the airbox with the gas tank still in place on the bike....Makes getting at the carb a much quicker process....

    First remove the airbox cover and filter, with the gas tank and everything else still in place...Then using a white grease pencil, I traced along the bottom edge of the gas tank onto the black plastic airbox...Then remove the gas tank..Here's a how-to on gas tank removal if you need it...http://www.vtxcafe.com/showthread.php?t=33679 Then remove the airbox from the bike..There's three screws at the carb, a bolt near the bottom, and one near the top...Also there's the crankcase vent tube in the back of the cover, and the tube for the PAIR valve system if you haven't already removed that from the bike...Once you have it off the bike, the fun parts starts...I used a cutoff wheel in my die grinder, but I know that not everybody has an air compressor at their disposal..A cutoff wheel in a Dremel will also work, and as well as a hacksaw...I chose the easiest and quickest way I had....Using the grease pencil again, continue the line you already drew around the sides and back of the airbox....Now when you start cutting, cut ABOVE the line you just drew, especially on the back....If you cut too low on the backside, you'll end up allowing unfiltered air into the carb, and you don't want that happening...So you need to stay above the flat area back there...Once it is cut, it'll look just like this....



    See that flat area at the top that I left?...Don't cut into that, or you'll be letting unfiltered air into the carb...Might take2-3 times to get it right...I cut it high all the way around, then went a little at a time until I could get it back on the bike with the gas tank in place back on the frame...I left it high on the backside, and when I remove the remaining mount locations (one gets cut off), I tilt the bottom out towards me so the backside will clear the tank bottom...Here's what it looks like with the tank off the bike...



    Big difference in the open area between this and the two small openings that were formerly the intake openings...You can also see how the filter sits in there, and why it's important to leave that flat area intact...Now all that's left is to put it back together...The crankcase vent tube on the backside can be a pain to re-attach, but it'll go back on there...Here's what it looks like all re-assembled on my bike with my waterjet-cut airbox cover by Lazerdude...Can't even tell it's been cut with it all back together..



    Now for a couple more items that need to be covered...Doing this allows alot more air to enter the carb and engine, so carb work is needed to keep the air/fuel ratio correct...Lots of other guys here have done this same mod, and I'm 99% sure that everybody here has followed Scar's carb tuning sticky to dial in their setup..We're all using 2 shims on the stock needle, and set the A/F screw to 2-1/2 turns out from lightly seated...With my particular setup (opened airbox cover + decap, I have the A/F set at 2-5/8, and could maybe use another 1/8 turn which I'm gonna try this year....

    Also I recommend getting a K&N filter...The stock one is a paper filter, and with the top chopped off the airbox, there's a decent chance of water getting in there if you get caught in the rain...Water will destroy the stock filter, but a K&N will be fine for the life of the bike...

    Best thing about this mod is nobody can tell it's not 100% stock...But it'll flat haul ass when the carb is dialed in to the increased airflow...Stealth mode at it's best!!..LOL!!...
    Last edited by Bassdude404; 03-03-2010 at 08:37 PM.

  2. #2
    rnich56's Avatar
    rnich56 is offline Senior Member
    Florida Riders Group
    Join Date
    Nov 2009
    Location
    Port Orange
    Age
    60
    Posts
    255
    Post Thanks / Like
    Thanks for the post. I was wondering how you did that.

    Nice job.

  3. #3
    bc13's Avatar
    bc13 is offline Senior Member
    Minnesota Riders Group
    Iowa Riders Group
    Join Date
    Mar 2008
    Location
    Southern
    Age
    33
    Posts
    2,214
    Post Thanks / Like
    Thanks bass. Great writeup. I have been waiting to do this and the scar mod to the bike. You should get a moderator to put this with the other sticky threads at the top of the 1300 forum. Thanks again, this is a great service to us that are looking to do it.

  4. Thankswino thanked for this post
  5. Remove Advertisements
    VTX Cafe
    Advertisements
     

  6. #4
    tattoowho's Avatar
    tattoowho is offline Senior Member

    Texas Riders Group
    Oklahoma Riders Group
    Louisiana Riders Group
    Join Date
    Jan 2009
    Location
    Athens
    Posts
    2,261
    Post Thanks / Like
    Nice write up Bass.

  7. #5
    robdawg13's Avatar
    robdawg13 is offline Senior Member
    Oklahoma Riders Group
    Join Date
    Oct 2009
    Location
    Leander
    Posts
    212
    Post Thanks / Like
    Really appreciate the write-up Bassdude - I have been debating on doing this mod next on my bike. I really like the idea of doing low and no-cost mods to my bike. That keeps me and the wife happy! Here is my dilemma - Right now my bike runs good with the stock set-up. Only mods done to the drivetrain are PAIR valve removal to clean things up and deep Clayton mod. (Oh yeah - and the seat pin mod - that alone is worth at least 10 HP -right? ) Starts fine with no choke, just a twist of the throttle before hitting the button, and I have no complaints on driveability. SO... how much tinkering is required to get it right after the mod and how much improvement are we talking about? Also - I don't see how water gets in if you don't do the "waterjet-cut airbox cover by Lazerdude" - what am I missing? And, lastly, how does it sound sucking all that air and how noticeable is the sound? Hope that's not too many questions - just don't want to do it and then wish I hadn't. Had a Trans Am a couple of years ago that I did a lot of mods to and the more I did to it the less I drove it. Don't want to make that mistake again...

  8. #6
    vjp5's Avatar
    vjp5 is offline Senior Member
    Indiana Riders Group
    Illinois Riders Group
    Join Date
    Jun 2008
    Location
    Palos Park
    Age
    54
    Posts
    1,835
    Post Thanks / Like
    As always, your time, effort and knowledge transfer is appreciated

  9. #7
    Bassdude404's Avatar
    Bassdude404 is offline The guitar, not the fish!
    Ohio Riders Group
    Michigan Riders Group
    Indiana Riders Group
    Illinois Riders Group
    Join Date
    Sep 2007
    Location
    Rolling Prairie, Indiana
    Age
    52
    Posts
    33,366
    Post Thanks / Like
    Quote Originally Posted by robdawg13 View Post
    Starts fine with no choke, just a twist of the throttle before hitting the button, and I have no complaints on driveability. SO... how much tinkering is required to get it right after the mod and how much improvement are we talking about? Also - I don't see how water gets in if you don't do the "waterjet-cut airbox cover by Lazerdude" - what am I missing? And, lastly, how does it sound sucking all that air and how noticeable is the sound? Hope that's not too many questions - just don't want to do it and then wish I hadn't.....
    Like I said, I was in the middle of tuning the carb per Scar's write-up when I decided to decap the airbox...Lot's of other guys running the decap mod with totally stock cover, with 2 shims, and about 2-1/2 out on the A/F screw...If I remember eight, I had it all dialed in by the end of the day, and I've been running it that way for almost two years now, and haven't had to touch the carb once...Very reliable...

    As far as water getting in, if you ride in the rain, water could possibly run down the backbone of the frame and get in that way...Wouldn't be alot, but it won't take much to destroy the stock paper filter...

    As far as intake noise, there was a big difference when I added the waterjet-cut cover...Don't remember if it got louder with the decap or not..Maybe someone that has done the decap and still has the stock cover can offer their experience on this...

  10. #8
    jacksvtx's Avatar
    jacksvtx is offline Senior Member
    Connecticut Riders Group
    Join Date
    May 2009
    Location
    Hartford Area
    Age
    52
    Posts
    1,588
    Post Thanks / Like
    You the man Bassdude!

  11. #9
    Join Date
    Feb 2008
    Location
    central PA
    Age
    47
    Posts
    332
    Post Thanks / Like
    Hey Bass, sorry. I must have been the cause of this post. Bassdude sent it to me once and till I was ready I lost it. Then I asked the second time. Bassdude, the good news is, bike in downstairs and mods will be tackled as soon as we get home. Thanks for your help man!!

  12. #10
    Bassdude404's Avatar
    Bassdude404 is offline The guitar, not the fish!
    Ohio Riders Group
    Michigan Riders Group
    Indiana Riders Group
    Illinois Riders Group
    Join Date
    Sep 2007
    Location
    Rolling Prairie, Indiana
    Age
    52
    Posts
    33,366
    Post Thanks / Like
    Quote Originally Posted by smoke View Post
    Hey Bass, sorry. I must have been the cause of this post. Bassdude sent it to me once and till I was ready I lost it. Then I asked the second time. Bassdude, the good news is, bike in downstairs and mods will be tackled as soon as we get home. Thanks for your help man!!
    Don't be sorry, no need...I've been getting PM's about this for the past several weeks now, about 2-3 a week...So I decided to just do it this way instead of re-typing the same info over and over...Been hanging oot at the "other" site also and getting the same questions over thetre, just not as frequent...So now when that happens, I'll post the link to this site instead....

Page 1 of 18 12311 ... LastLast

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

    Similar Threads

    1. Urgent Help Help airbox
      By FLIPBEL in forum Honda VTX 1300 Forums
      Replies: 7
      Last Post: 11-22-2008, 09:16 AM
    2. Hey Bass - airbox decapitation question
      By deranger in forum Honda VTX 1300 Forums
      Replies: 3
      Last Post: 11-07-2008, 03:46 PM
    3. Airbox Help!!!
      By nothingstranger in forum *** The Shop ~ I NEED URGENT HELP!! ***
      Replies: 3
      Last Post: 10-07-2008, 11:51 AM
    4. Airbox ??
      By rjtmac in forum Honda VTX 1800 Forums
      Replies: 2
      Last Post: 09-08-2008, 08:39 PM
    5. Airbox mod
      By KevTN in forum Honda VTX 1800 Forums
      Replies: 4
      Last Post: 04-20-2006, 10:05 PM

    Bookmarks

    Posting Permissions

    • You may not post new threads
    • You may not post replies
    • You may not post attachments
    • You may not edit your posts
    •