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Auxiliary tank for R1200RT that looks factory.


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Just finished the prototype of my version of an Auxiliary Fuel Tank For an R100RT.


The tank itself is custom made to conform to the rule requirement for most if not all

Rally organizations. 4.4 gallon capacity + 7.1 main tank capacity = 11.5 gallons total, and incorporating the unique design features of this system.


Notice that there are no external fuel hoses pipes or other noxious looking devices.

The tank itself uses a non vented gas cap and is internally vented, ”Patent Applied for”.

The only visible plumbing, visible from anywhere is the little red knob which is the fuel valve.


The tank is gravity feed, does not require modifying the bike in any way and utilizes

ALL the BMW designed pollution control devices with no venting direct to the atmosphere.


Utilizes the stock “Safety valve” which is a combination float valve rollover valve and maximum pressure relief valve vented to the charcoal canister.


The design incorporates a recalculating expansion tank sized for a 50 degree temperature change based on both tanks being filled to capacity at the lower temperature.


The top box may be fully opened with the tank in place.


The tank and mount are attached to the bike using the stock passenger seat brackets and the two screws in the stock luggage rack mounting. Remove 2 screws disconnect two quick disconnects and the stock passenger seat goes back on, takes less than 30 seconds.

I originally considered using the seat lock but opted for the two screws which gives the tank and mount a rock solid base.


The under side of the mount can hold up to threequart bottles of oil.


The tank can be removed by undoing 4 mounting bolts and two quick disconnects and the mount itself can be used as and additional 12” X 12” luggage rack.


I am working on a back rest to mount directly to the tank and tank mount.


The entire system can be removed and the bike returned to stock configuration in about 20 minutes with absolutely no indication that it has ever been there, no modification of the bike whatsoever, no drilling of the stock gas tank tank, no drilling of any of the Tupperware, no grinding or filing.


The tank in the photo is still a rough prototype haven’t even filed saw marks left by the jig saw used to cut the aluminum it is constructed of, still looks presentable and “FACTORY” as it is.


I started out try to just build a decent looking auxiliary tank for my own use but it has

Turned out so well I figure others would be interested in it.


The design is adaptable to other bikes I just don’t have any others to use for prototyping.

My 2 Harleys, which at the present time have the fugly black plastic things with hoses hanging all over them, soon to be changed.


Have not been able to get the attachment feature to work for the picture.

If there is any interest in this tank design drop me an email at cranezilla@yahoo.com.

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