Tail Light and Rear Guard Brace
The loose tail light and rear guard flex problems can be solved without major expenditure with two modifications.
There are two spare bolt holes in the rear frame which can be used to prevent the flex without the expense of an added brace using 2 of 5x30mm bolts and 2 of 12x18mm spacers with 2 grommets.
Access to the tail light connectors can be provided at the same time by drilling a 1 1/2" (38mm) hole.
The sub frame is common to all models. The plastic base (wheel cover) is the same F650GS/M, G650GS and Sertao. A brace (Tubular Frame) is the same F650GS/M, G650GS, Sertao. There are two No Plate Holders, one for the F650GS and G65GS and one for the Dakar/Sertao.
The rubber mounts for the tail light to the plastic holder allow it to flop around. This can be improved by removing the tail light and reducing the height of the metal spacers inside the rubber grommets by 1 or 2 mm, allowing more tension on the rubber grommets. An option is to drill the bolts to use cotter pins & larger washers instead of nuts. The PDF below has more details.
This modification mounts the assembly direct to the rear sub frame and enables the assembly to remain in place whiile working on the bike and simplifies connection of wiring. An added benefit is that it can overcome any breakage of the existing plastic mounts.
Remove the tail lamp and holder from the machine
Remove tail light from the holder
Drill the tail light as per the template
38mm hole in the centre and 5mm holes each side
A pdf with the template and more detail TailLight PDF
Two spacers are required for positioning the No Plate Holder
The spacers can be plastic or alloy and cover or replace the nut.
Spacer Dimensions - 18mm OD, 6mm ID, 12 mm high
Fit the 5 mm bolts using loctite under the heads
Tighten the nuts again using loctite
Re assemble the tail light to the holder
Re connect the wiring
Note in the pic below that the 5mm bolts mount the assembly direct to the sub frame so the plastic mounts are secondary mounts for the plastic base under the seat
Fit the grommets to the sub frame holes
Slide Tail Light into place on the grommets in the sub frame
Fit the washers and nyloc nuts
Re assemble any other parts removed for access
I set this up on my 02 Dakar years ago and have had no dirt or water problems with the tail light area.
Note. On the Dual spark and G650GS use 6 mm bolts to match the Tubular Frame mounting bolts.