Motor Trike auxiliary fuel tank ID needed

[BVG123]

can any one indemnify this tank . And have any info on it .I know it goes under the seat behind the main tank, but wondered what the large hole is for. Any info would be appreciated

 

[CrystalPistol]

Don't some trike kits for 1800s still use the bike's shock with maybe stiffer spring or air bags, etc?

 

[BVG123]

Don't some trike kits for 1800s still use the bike's shock with maybe stiffer spring or air bags, etc?

HI. If it had a solid axle it would but most kits on 1800s are independent