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Thread: Could some one explain the differences in the bikes, Air head, hex and so on.

  1. #1

    Could some one explain the differences in the bikes, Air head, hex and so on.

    Hi all, I thought I had a Hex head 2009 1200rt until I started working on it, adjusting the valves, I need both hex and star, sockets and closed end wrenches. I have most but not the star at all and I've sure never seen the type of valve adjustment BMW uses on their bikes and I've adjusted older cars, 55 Chevy and newer and older Harley's and other Japanese too, none looked or needed all the loosening of bolts that my bike does. I had to ask at Lowe's what the "Star" head bolt was called and there are other head types too but not on my bike, a real learning experience of which I'm enjoying and having fun. I have a Clymer repair manual which gives good pics and explains well. I could not get my back wheel to turn in sixth gear though so used a big wrench since I didn't have a big enough socket and don't know what size it is for the big nut at the front where the alternator belt is, but will find out. The bike runs great but I don't think the valves are adjusted correctly at all and will find out and adjust. I'm pretty picky about the way engines run, any, I can hear plugs missing when others can't, my ears are really good.

    Now, could some one please explain why the different BMW's are called Air Head, Hex etc, if this is explained some where I've missed please point me in that direction, thanks.

  2. #2
    Debbie's Servant Lee's Avatar
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    Quote Originally Posted by jyme View Post
    I could not get my back wheel to turn in sixth gear .
    On my bikes when I rotate the rear wheel I bump it a little at a time.
    Lee
    2016 R1200RS
    MOA # 30878
    Past BMW Bikes: 2011 K1300S, 2003 K1200RS, 1991 K75S, 1987 K75T, 1984 R100RT

  3. #3
    Liaison 20774's Avatar
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    To turn the engine, I probably wouldn't use any type of alternator bolt at the front of the engine unless the spark plugs were removed. Using the rear wheel with transmission in gear is easier but again you'll be fighting the engine compression.

    Quote Originally Posted by jyme View Post
    Now, could some one please explain why the different BMW's are called Air Head, Hex etc, if this is explained some where I've missed please point me in that direction, thanks.
    Not sure I've seen a complete list of differences or background on the names, but this wiki page has a start:

    https://en.wikipedia.org/wiki/Histor...ies_flat-twins

    But my 30000 foot definition for flat horizontally opposed engines:

    - Airhead -- nominally, this has been used for the models from 1970 to 1995 (Type 247 engines, also including the R65 which is Type 248 IIRC). The jugs stick out to the side and the primary cooling is due to air flowing over the cylinders. That can be said of all BMW twins going back to 1923 but generally it's just the 1970-1995 bikes. More than you ever wanted to read on Airheads here:

    http://bmwmotorcycletech.info/models.htm

    - Oilhead -- what was added was more oil flow paths around the head, thus adding some cooling effect due to the oil flowing

    - Hexhead -- still like the Oilhead, but I think the "hex" part of this has something to do with the design of the valve covers, heads, or something like that

    - Wethead -- this version has water cooling added

    Not sure if it's a universal thing, but S1000 ranges of models were given the "Hothead" designation on our forum due to the performance and racetrack use of the bike. Other models have been called "Bricks" (K series) due to the squareness of the engine case, Wedge bikes due to the slanted transverse engine case. Just to name a few...
    Kurt -- Forum Liaison ---> Resources and Links Thread <---
    '78 R100/7 & '69 R69S & '52 R25/2
    mine-ineye-deatheah-pielayah-jooa-kalayus. oolah-minane-hay-meeriah-kal-oyus-algay-a-thaykin', buddy!

  4. #4
    Debbie's Servant Lee's Avatar
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    Quote Originally Posted by 20774 View Post
    unless the spark plugs were removed. Using the rear wheel with transmission in gear is easier but again you'll be fighting the engine compression.

    ..
    Thanks, I forgot to mention removing the plugs.
    Lee
    2016 R1200RS
    MOA # 30878
    Past BMW Bikes: 2011 K1300S, 2003 K1200RS, 1991 K75S, 1987 K75T, 1984 R100RT

  5. #5
    Registered User GTRider's Avatar
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    And there are “camheads” in the mix as well...

    Best,
    DG
    DGerber
    1983 R80ST 1984 R80 G/S PD 1993 R100GS 2004 K1200GT w/Hannigan S/C 2010 K1300GT
    BMWMOA#52184, AMA#271542, IBA#138

  6. #6
    Hi, and thank you, I've been working on cars and trucks since the late 60's and the first thing I was taught if working on the engine as I am with this motor cycle, worked on them also since the same time frame is to pull the plugs. You may not always have to pull the plugs but as the activity dictates was suggested.

  7. #7
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    I see you are adjusting the valves, let me just add a word of caution on removing the spark plugs. Make sure you have the correct socket, thin wall so it doesn't get stuck. BMW sells a socket for this purpose. There are many posts of people getting the socket stuck and it's a bad day.

  8. #8
    Quote Originally Posted by jyme View Post
    I had to ask at Lowe's what the "Star" head bolt was called and there are other head types too but not on my bike
    It's called a Torx
    https://en.wikipedia.org/wiki/Torx

    And although your thinking made sense, the name "hexhead" doesn't come from the 6 points of the Torx bolts but from the overall hexagonal shape of the valve covers.

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