Fuel tank interchangability

Discussion in 'Airheads' started by patrkbukly, Sep 29, 2013.

  1. patrkbukly

    patrkbukly 52 Weeks of warm

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    #1
  2. pjcr12

    pjcr12 Stercus accidit

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    Yes, I used a /5 tank on an R80/7 and it looked forking ace, as well as increased fuel capacity. I'd show you a pic of it except I can't because of a combined fuck-up between firefox and photobucket which crashed my computer 3 times
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  3. Big Bamboo

    Big Bamboo Aircooled & Sunbaked

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    The early tank and the later tank have 24 liters, or 6.34 gal. total capacity The early tank will be shorter, front to back, than the later tank, so there will be a gap between it and the seat. Does the '80 still have the master cylinder under the tank? If so, make sure any tank you buy has the space for it. The tank in your link has screw on emblems so it's a very early /5 tank, not sure if it will have that M/C gap. It also has the hinge for the cap on the front. IMO Duncan overprices everything he sells, buyer beware!
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  4. JonnyCash

    JonnyCash turd polisher

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    It would work, as long as you don't have an under-tank master cylinder, which I don't think you would. The biggest issue I can see here is that you should not pay this guy anywhere near that much for that tank. That guy always has his stuff priced at about double the going rate. Shit, I just sold the same tank on an ebay auction for $60. It needed more work than that one, but it was definitely not junk.
    #4
  5. pjcr12

    pjcr12 Stercus accidit

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    [​IMG]
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  6. Rob Farmer

    Rob Farmer Long timer

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    Can't beat something thats built in a proper shed :D
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  7. Big Bamboo

    Big Bamboo Aircooled & Sunbaked

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    Your center stand is sacked...
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  8. disston

    disston ShadeTreeExpert

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    The /5 bikes had mechanical brakes on all models. Beginning in 1974 with the /6 bikes most models got hydraulic brakes up front. The master cylinder for the front brake is under the tank on a 1980 bike. You have Ate front brakes? And this is the type of gas tank you have?

    [​IMG]

    May not be that color but that is the type of tank you have? The /5 tank will not fit if you still have the MC under the current tank. You will also have to use a /5 or /6 seat with the /5 tank because the /7 seat will leave a gap between tank and seat.
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  9. Big Bamboo

    Big Bamboo Aircooled & Sunbaked

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    Actually, around 1973 the large /5 tanks started coming with the gap for the M/C, and all the small tanks have it. Read Duanes excellent article on it: http://w6rec.com/duane/bmw/tank/index.htm
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  10. disston

    disston ShadeTreeExpert

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    I have a 1973 large tank that has stick on emblems instead of screw on. It looks exactly like a /6 tank but it has a /5 tank bottom and does not fit my /6 bike. This may not be the case with small tanks but I was bit once already by a large /5 tank and want to warn those looking that it is not likely the tank will fit if the master cylinder is still on the frame.

    To OP,
    Several times we have mentioned this issue about the master cylinder. Your bike was made with the master cylinder on the frame under the tank. It is a popular mod to put a later model master cylinder on the handle bars and then you don't have a need for the large space of a /6 or /7 tank.

    If your bike is stock and still the way BMW built it then the tank you have been looking at doesn't fit your bike.

    Pretty simple really.
    #10
  11. Big Bamboo

    Big Bamboo Aircooled & Sunbaked

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    Here is the large tank with the stick on emblems and forward hinge that came off my 1973 R75/5: To the OP, note the gap for the master cylinder. The tank Duncan is selling does NOT have this gap: [​IMG][​IMG]
    #11
  12. patrkbukly

    patrkbukly 52 Weeks of warm

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    Thanks Big Bamboo,
    And since I have that master cylinder under the tank, unless I move it to the throttle mount master I am SOL?

    And yes Disston that does look like the tank I have.

    Speaking of....can I install the throttle mounted master cylinder like my PD has or not enough umpf to close those 2 calipers?

    Got to be an easier way to get more fuel in this thing.
    #12
  13. Big Bamboo

    Big Bamboo Aircooled & Sunbaked

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    On further searching, it appears they are the same. It is a very good idea to switch to a handlebar mounted master cylinder. Others with more experience with the nuts and bolts aspect of that will chime in shortly. The huge crack and recent repaint on that tank on ebay speaks of bodywork done poorly, I'd pass on that one. If I were going seriously off the beaten path, I'd carry a few small backpacking fuel containers.
    #13
  14. disston

    disston ShadeTreeExpert

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    The last time a decent /6 tank with an OEM black paint job sold on Ebay was only about a week ago. I lost . That tank went for $670 with a shipping charge of $40.

    A decent /6 tank in black is very hard to find. If you will take another color and maybe paint it not so bad.

    Why do you think you need more fuel than a standard large tank holds? There are the Luftmeister saddle bag tanks.

    Here is an older thread about large tanks.

    http://www.advrider.com/forums/showthread.php?p=11895482
    #14
  15. garyinalt

    garyinalt Adventurer

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    The tank with the narrow bottom and stick on emblems might just be a /6 part for the R60/6 which was the only model 1974-1976 with the drum brake up front. So there was no master cylinder to contend with under the tank.
    #15
  16. patrkbukly

    patrkbukly 52 Weeks of warm

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    well, I'm contemplating getting a set of the Luftmeister side panel tanks. 1 gallon each I believe and that would bring it from 6. something to 8. I am just too damned spoiled from my PD but that RT is so damn comfortable.

    Not my bike but these side tanks.
    [​IMG]
    #16
  17. DiabloADV

    DiabloADV Semi-Occasional

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    Will the R65 tank fit a /6 frame ? Longer or shorter than /6 tank...?
    #17
  18. disston

    disston ShadeTreeExpert

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    I thought the Luftmeister side tanks were 1 liter each. I'll try to look it up. Not sure of course but I think I read this some where yesterday.

    Edit; I give up. Every mention of these tanks seems to have a different idea about how much gas they hold. One source says 1 gallon + 8 ounces but does not say if this is each or total. Other sources say a little less than a gallon each. One source said a total of 3 to 4 liters and finally several sources said about 1 liter each.

    Some riders who had them eventually got rid of them because they are weird. They are plumbed weird and they work weird. Some riders did like them

    Good luck finding these. They are getting harder to find and more expensive all the time.

    I like them because I like weird. Wish I had a pair myself.
    #18