'73 Suzuki GT250 - Part 3 - Fitting aluminum Yamaha MX fuel tank to frame

Idea for this build started from this fuel tank, which had been for sale for a while in one Finnish spare parts advertisement website. I contacted the seller by phone and we settled a deal for the tank. He wasn't sure of the tanks origin. I believe it's originally from a Yamaha MX. Once the deal was done it didn't take long for it to arrive by mail.

Aluminum Yamaha MX fuel tank.

Once I got it I noticed that the rear mounting bracket of the tank was broken. I removed the remains of it with an angle grinder and a sander. I cleaned the area below the old bracket with a sandblaster and a piece of sand paper. 

I made a small bracket out of 3 mm aluminum sheet and bend it to a shape of a trapezoid. I finished it by filing a stadium shaped hole to bottom of it. Since I wasn't able to weld aluminum I visited Mikko from Speedhouse and he welded the bracket for me for a small reward. Mikko builds and maintains motorcycles for a living. You can find few pictures of the bikes he has build from his website: http://www.speedhouse.fi/albumi/pyoria/. 

Tank didn't came with any locating dampers so I had to order a pair of them (3TB-24181-00) from one of my local Yamaha parts dealer. Once I had them it was easy to design a front mounting bracket for the tank.

Tank had a broken rear mounting bracket.

New one is made out of 3 mm aluminum sheet.

Pair of locating dampers (3TB-24181-00).

Underside of the tank.

I started making the front mounting bracket by bending a suitable rounded shape out of approximately 80 mm wide steel sheet. I used 2 mm thick mild steel for two reasons. First one being formability and second structural strength. I made small bevels to both sides of the top plane of the bracket. That made sliding the tank to its place easier. I tack welded two thin pieces of sheet metal inside the bracket to keep the tank from moving sideways. Once that was done I tacked it to the top tube of the frame. 

Finished front mounting bracket.

Side view.

Bracket tacked to the top tube of the frame.
Seems like I forget to remove mill cinder before welding.

Rear mounting bracket of the fuel tank needed a counter part, which I cut out of flat bar. I drilled a hole to the center of it and tacked a hexagon weld nut to the bottom of it. Once I figured the right angle for the tank I tacked the piece to the frame. I didn't want to weld either of the brackets definitively. If there's going to appear any fitment issues in the future, for example with triple clamps, it's easier to move their position.

Counter part for the rear mounting bracket.

Both brackets tacked in place.

Test fit.

Next time I'm going to start fitting the aluminum RM/PE 250 swingarm, which you can see in the background. Stay tuned for that next week!