Velocity Stacks

Discussion in 'The Garage' started by Donk, May 2, 2012.

  1. Donk

    Donk n00b

    Joined:
    May 2, 2012
    Oddometer:
    6
    Location:
    Cape Town South Africa
    I am building a Cafe Racer from a 1981 BMW R100RS donor bike.
    I'm situated in deepest Africa...and ask if anyone can help me find velocity stacks for 40mm Bings?
    #1
  2. OldPete

    OldPete Be aware

    Joined:
    Oct 6, 2007
    Oddometer:
    5,890
    Location:
    SoSoCal
    Having owned two airheads, i will offer.

    The stock intake system offers clean air and decent boot clearance.

    I am not fond of the kewl cafe fad that is happening to old BMWs but if one wants a better airhead do three things.

    Better suspension.
    Best tires in the proper sizes... no over tired rims.
    Frame struts to stiffen up the wet noodle frame.
    #2
  3. Bugman98

    Bugman98 Been here awhile

    Joined:
    Mar 10, 2008
    Oddometer:
    206
    Location:
    Soonertown, OK
    Did you even read the OP's post? :deal

    He wants help with velocity stacks, not suspension and frame mods.
    #3
  4. CycleDoc59

    CycleDoc59 Wrench Rider

    Joined:
    May 24, 2006
    Oddometer:
    984
    Location:
    East Virginia
    Don't know about where you are, but here if you Google "40mm velocity stacks",
    you'll get bunches, of many different lengths and various types of mounting....
    #4
  5. OldPete

    OldPete Be aware

    Joined:
    Oct 6, 2007
    Oddometer:
    5,890
    Location:
    SoSoCal
    Yes i did.

    Velocity stacks are for show not go. :1drink

    EDIT: So offer something on rejetting with stacks & prolly unknown modified exhaust. lol
    #5
  6. CycleDoc59

    CycleDoc59 Wrench Rider

    Joined:
    May 24, 2006
    Oddometer:
    984
    Location:
    East Virginia
    Might wanta check this out: http://en.wikipedia.org/wiki/Velocity_stack
    #6
  7. OldPete

    OldPete Be aware

    Joined:
    Oct 6, 2007
    Oddometer:
    5,890
    Location:
    SoSoCal
    I've done my share of tuning. :wink:

    The stock airhead offers a long intake runner that smooths air flow.

    There is alot of cafe airhead threads in the airhead section of oldscool. :1drink
    #7
  8. Donk

    Donk n00b

    Joined:
    May 2, 2012
    Oddometer:
    6
    Location:
    Cape Town South Africa
    Thanks for your comments Guys...what I am really asking is if anyone knows where I can purchase suitable velocity stacks. Yes I am changing an old worn-out banger and completly rebuilding it to my own specs. My thread is
    http://www.wilddog.za.net/forum/index.php?topic=86209.0 where you can see what I'm up too.
    I also own a 2011 BMW GSA which my wife and I tour the African countryside in style. 16000k's in 9 months.
    #8
  9. OldPete

    OldPete Be aware

    Joined:
    Oct 6, 2007
    Oddometer:
    5,890
    Location:
    SoSoCal
    I have no idea where to get stacks for Bings. Nice work BTW. :clap

    The only bike i ran stacks on was a '77 900SS and installed Uni filters over them.

    The Boxer's intake is in an area that is quite dirty, unlike a Guzzi... but they do look the bizness.

    I had a R100RT and can't remember the exact year... '81 or '82.
    It had an RS type engine with 40s & large valves... a touring motor it was not because it lacked mid-range.

    If you're into the engine, read this thread.. http://www.advrider.com/forums/showthread.php?t=777955

    Having tightened up the squish on two 948cc Guzzi engines, i can say w/o reservation that it works a treat at keeping detonation at bay.

    May i suggest you post in the airhead section of oldscool forum.

    Note: My older Brother spent 6 years in the RSA and remarried while there... nice lady, Molly.
    #9
  10. P B G

    P B G Long timer

    Joined:
    Mar 7, 2008
    Oddometer:
    10,001
    Location:
    Greater Chicago
    IIRC, bings being CV carbs aren't the hugest fan of less restrictive intakes.

    Love the look though.

    What sizes have you been able to source locally?
    #10
  11. MODNROD

    MODNROD Decisions, decisions

    Joined:
    Feb 20, 2009
    Oddometer:
    2,201
    Location:
    Midwest, West Oz
    In the past when I've needed stacks but none were available, I've used PVC tubing.
    Heat in oven to 100*C, carefully pull out (gloves if your fingers aren't croc skin), then slide over the back of an upturned glass. Different glasses, different tapers.

    To REALLY upset the BMW purists, leave them as obviously PVC..........:norton

    Have fun.
    #11
  12. vfxdog

    vfxdog Been here awhile

    Joined:
    Jan 5, 2007
    Oddometer:
    627
    Location:
    Santa Monica or London, depending on work.
    #12
  13. Donk

    Donk n00b

    Joined:
    May 2, 2012
    Oddometer:
    6
    Location:
    Cape Town South Africa
    Problem is I cant source these anywhere in SA
    #13
  14. Donk

    Donk n00b

    Joined:
    May 2, 2012
    Oddometer:
    6
    Location:
    Cape Town South Africa
    I'll give it a go ...thanks for the heads up.
    #14
  15. Donk

    Donk n00b

    Joined:
    May 2, 2012
    Oddometer:
    6
    Location:
    Cape Town South Africa
    Thanks vfxdog...I have sent them a mail...hope I get a reply!
    #15
  16. ttpete

    ttpete Rectum Non Bustibus

    Joined:
    May 13, 2009
    Oddometer:
    6,246
    Location:
    Dearborn, MI
    You'll be needing an overhaul in short order with stacks 12" off the ground. They'll suck up everything the front wheel kicks up. Dumb.
    #16
  17. OldPete

    OldPete Be aware

    Joined:
    Oct 6, 2007
    Oddometer:
    5,890
    Location:
    SoSoCal

    QFT

    In the order of impact, intake valve seat, intake valve guide, then piston rings and last and very least the exhaust valve seat.
    At the point of shift, oil will get sucked down the worn intake guide and several things will happen.
    Smokey exhaust, detonation :eek1 and oil will turn into coke on the port side of the intake valve restricting breathing.

    Great fun for induction noise and posability. :lol3


    NOTE: This is the last airheaded thread i will in. :1drink
    #17
  18. Donk

    Donk n00b

    Joined:
    May 2, 2012
    Oddometer:
    6
    Location:
    Cape Town South Africa
    End of story...thanks for all your advise...wont be going this route after all!!
    #18