I have done a couple of custom 3D tanks, utilizing body filler mostly, then carving out. I don't use loads of it, but if one side of the tank has the design, can it offset the balance? I just do not want to create a design that would create a problem for the rider.

Thanks cutom motorcycle tank

  • Welcome to Motor Vehicle Maintenance & Repair! Isn't body filler really just plastic? I really don't think it would cause an issue, but I'm no expert. Commented Aug 10, 2019 at 2:45
  • Thank You! It's more on the side of hard putty. I really don't think it would create a problem, I'm just wondering how far I can take the designs before I need to start considering balance. I have a customer who wants a demon with horns coming out of the tank, and Im worried about that being an issue. Commented Aug 10, 2019 at 2:56
  • Customers just want, want, want, want, want ... eh? Actually, I doubt it will be an issue. I don't think you could put enough of anything on there to make it lean one way or the other ... not body filler, anyway. Commented Aug 10, 2019 at 3:00

3 Answers 3


The difference in weight one side to the other will be small. You could test this by hanging a tank prior to the modelling process ie before you start cutting filler, from a string and see or mark the lowest point. Once complete, hang again and see the difference... I would hang from the filling cap hole...

Just a point, the fuel moving around is much greater than the filler difference...

Make a filler cap adaptor with a secure fixing or hanging loop - last thing you want is an accident...


If the quantity of putty is relatively small relative to the weight of the motorcycle and the designs are symmetrical to center line of the tank there shouldn't be an issue with balance. Designs that affect the profile of the tank contour would affect the aerodynamics of the motorcycle. Then the only issue is increased fuel consumption.

My background is similar to yours with regard to design (Architectural in my case) in the Old School days. Largely retired from the field.

  • That tank does look good though, do you post pictures of all your work?
    – Solar Mike
    Commented Aug 10, 2019 at 5:44
  • No I don't usually, but it's hard to explain what I'm talking about otherwise. And thank you Commented Aug 10, 2019 at 14:05

Side-to-side imbalance in a motorcycle will result in the motorcycle traveling down the road in a straight line, while being not quite at 90˚ to the vertical. (Because roadways themselves are usually not horizontal, being tilted a bit away from the middle, a more accurate statement would be that the bike will lean towards its lighter side, so the bike's center of mass remains over that point on the ground which is between the centers of the two tire contact patches.)

Putting more weight in one saddlebag than in the other demonstrates this easily. Unless the weight difference is more than 6kg or so, the rider's not apt to even notice it.

  • Think the difference in filler side to side might be +/- 60g not 6kg... I think 6kg of filler extra on one side would be noticeable...
    – Solar Mike
    Commented Aug 10, 2019 at 20:43

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