Reddit reviews ALPHA MOTO Motorcycle Shop Auxiliary Gas Fuel Tank Professional Tool Compatible with Honda Yamaha Kawasaki Suzuki KZ XS CB KS 450 550 650 750 850

Auxiliary Gas Fuel Tank
https://www.amazon.com/dp/B004NV42PQ/ref=cm_sw_r_cp_apa_i_gD3QDbCDVGF4Q


Edit,

For many years my test tank at home for carb work was just a 1qt gear oil bottle upside down, with a coat hanger punched through the sides to make a hanging loop, a hole cut in the bottom of the bottle(now the top) to fill and a clear fuel line pushed onto the gear oil spout.

You can buy similar devices online, although most shadetree mechanics I know usually just hack something together. I used to use an abomination I bodged from a mic stand, a water bottle, and an old petcock--and my friends considered that unnecessarily elaborate.

http://www.amazon.com/motorcycle-shop-auxiliary-fuel-tank/dp/B004NV42PQ/

$25 on amazon, also at every online bike parts store

I was going to build something, but the parts to include a cutoff, hanger, hose, etc and make it gas-proof cost more than the real deal.

plus, I got to buy another doodad for the shop!

I have an auxiliary fuel tank like this.


Carbed motorcycle gas tanks often have 3 or 4 lines running to/from them depending on whether the petcock is vacuum-operated or not. There's the fuel feed, the vent, the overflow, and on a vacuum-operated petcock, the vacuum line from the carb(s).

To hook up an auxiliary fuel source, you'd plug the vacuum line (if present), hook up the fuel feed into the carbs to the aux tank, and just pretty much ignore the others.