It should sit level on
level ground.
Eliminate the simple things:
Check for uneven air pressure in the rear tires.
Shocks are same length when no rider/passenger on trike.
Tires are the same size and profile.
Rear fenders not mounted at the same height on either side of the body.
Suspension works freely up & down without air in the airshocks.
If tourpak is not mounted level even when the body is.
After the above checks and it still looks as though it is leaning:
Trike body deck is not level (where tourpak sits).
Trike body frame is not level.
The rear axle is not level or parallel ******
We are assuming that the trike has never been wrecked.
When building a trike they have to start with a level platform.
All manufacturers have tolerances to allow for variations of fitment.
If the frame where the body attaches is not level, the rear axle is not parallel to the frame and body frame, nothing that bolts on top of it will be level either. And on Harley-Davidson in particular the rear shocks mount to the body frame and rear axle. If the body frame is out of level or the rear axle is not parallel ... voila ... everything is crooked.
To check this:
Remove the seat and the rear body.
With all initial checks above and on
level ground, place a level across where the seat set on the frame. There are 2 spots on the frame (where the seat was) used while jigging the frame, lay the level across both. This will be the control level whatever the reading.
If you are really anal you can place a screwdriver under the tire to get ZERO.
Now go to the body frame and lay the level across the frame that the body sits on.
Lastly find a spot on the rear axle housing tube to lay the level.
I use a digital level and except a variation of .1 degree difference.
That is 1/10th a degree. If the differences between the reading between the 3 locations exceed 1/10th a degree, I make an adjustment.
***** Someone posted that increasing the air pressure in the shocks to 50psi made it level out somewhat. This would indicate an out-of-level rear axle or body frame.
I am sure these checks are not made at the factory where they rely on the parts off the shelf to fit.
Sometimes just loosening the bolts and re-tightening them will make the changes necessary.
This is not rocket science we are dealing with.