All models of Maxim-X share the same chrome side covers over their Mikuni carburetors - the covers which identify the 5 VALVE per cylinder engine that's unique to the Maxim-X in that era of Yamahas. Yamaha refers to the covers as either MANIFOLD COVERS or CARBURETOR JOINT COVERS. All models of Maxim-X share the same part numbers for those items: 1AA-13564-00-00 (Left) and 1AA-13594-00-00 (Right) and there are no superseding part numbers.

These covers are chrome over plastic and over time, due to heat deterioration and careless over tightening, the mounting points tend to crack until plastic fragments eventually begin to break away. In the above image there is a clearly visible crack which has begun to form across one of those mounting holes.

Tragically, replacement covers are no longer available from Yamaha or any after-market source except perhaps from someone selling their used parts. If you've had a look on eBay recently, you'll know that there isn't much hope of replacing these covers once they're too damaged to use any longer - there just aren't that many people selling used parts for the Maxim-X, much less these sought after chrome covers. The only option left is to reinforce the covers to prevent cracks from expanding or from forming in the first place. Whether your covers are cracked or not, the following reinforcement techniquie can (and probably should) be applied.

To reinforce the areas where cracks usually appear, it's as simple as glueing some form of reinforcement over the weakened area. I found that the easiest solution was to use Loctite Super Glue (the Gel kind) together with a suitable steel washer for the job. Gel super glue is thicker than usual super glues so it won't run all over the place and it also has a unique ability to actually fill out some uneven spaces to form a better mating surface where it might otherwise be uneven and weak. The washer should be stainless if possible and should be thick enough and hard enough to resist bending, otherwise it won't help the plastic resist flexure when tightening the mounting screws.

Of course, it's wise to clamp your glued parts until the glue has dried completely (see images below). Although super glue is advertised as bonding almost immediately, that simply isn't true. It dries more quickly than most glues but it too benefits from a solidly clamped connection for a suitable period of time. Be careful not to glue the clamps themselves to anything and be careful that you don't inadvertently reposition the washers by applying/tightening whatever clamps you use. It could become a real problem if you super glue a washer in a position where it blocks a screw hole or where it isn't as inconspicuous when viewed from the front of the cover. Clamping is essential but do it carefully.

If everything is done correctly, the washers will be solidly bonded and aligned in such a way that they're barely visible when mounted on the motorcycle... if they're visible at all (see images below).

The newly reinforced covers can, of course, still be damaged by careless overtightening but however you treat them, they'll definitely last a lot longer. With care, they may never break and may never need replacing.