AS Mark says , without knowing where you have already been it is pointless for us to try to recommend “ new” roads or places for you to scope .How long ago were these four rides through Mexico and Central America ?
The best advice for you at this time is to remember exactly all the roads and all the places you have already visited and then to set out on your travel while avoiding to repeat using exactly those same roads to the already seen places. Don’t fall into a habit revisiting the same places just because you know them. There are enough different roads and places to keep you busy for years . Of course certain repeats are unavoidable , as in the border approaches , but keep it to the minimum possible .

With “2 or 3 “ months available you should have no problem riding and exploring at a comfortable , relaxed slow pace . Best would be to leave the northwest of Mexico and the CC for the very last so that you do not hit winter weather of January there. The CC and Mex 40 are actually quite close to the USA and would be fitting for a dedicated trip in months with a guarantee of warmer weather . Apply your time to the more distant targets first .

Your past visit to the CC must have been in a good - weather month . By now you should have learned that even the Mex 40 route from Villa Union ( near Mazatlan) north and up the Espinazo Del Diablo Mountain could in January deliver you at the summit into icy/snow covered highway at La Ciudad : not the best proposition on a motorcycle!
When you do the Mex 40 the old LIBRE is the most curvaceous , the 40D toll road is the new bypass with many tunnels and the big bridge span . In spring/ summer you can relax about weather and do the area justice and explore the Espinazo segment of the toll road as an additional easy loop. Time your ride to stop for the night in El Salto . Don’t try running the whole thing Mazatlan-Durango in ONE day!!! Leave that to the old hands who live there and have no interest in sightseeing and want to cannonball it to their "destination".
The 40 D has entry/ exit points at the north side of El Salto in the high country and at Corte Alto , south of and below the snakiest section of the Libre 40 . If you use these two junctions you can for the cost of a toll make a loop which gives you a sampler of ONE pass on the NEW highway of about 60km including that big cable-stay bridge and tunnels and TWO runs along the hundreds of curves of the old 40 with its excellent pavement and light traffic. Enjoy!!!!



As Costa Rica appears to be your farthest extent of riding in your four preceding trips then that leaves Panama as the only option left for suggestions .
Okay ; so in Panama do make the effort to ride up into mountains on the side roads north and south off the PanAm highway . Bee-lining that major highway east would leave you wondering about how low , warm and dry the country appears to be .
Visit Volcan ( town name, in mts north of David) and the epically scenic high country loop roads on the west- side of Volcan Baru , then do the east-side road north and UP to and beyond Boquete. Lots of stuff to visit or hike to waterfalls etc .
Same applies for a visit to other north mountain towns Santa Fé and El Valle . You must see them to understand .
Do the southern peninsula of Chitre and ride the loop road to the south coast near Tonosi - you can not get any farther south than THAT on the continent .

Visit the various points along the renewed Panama Canal .

Ride all the way to Yaviza on the paved highway and see the Darien jungles up to the Darien Gap . Walk the bridge in Yaviza and you are in The Gap .

You can enter and exit Panama at three points from Costa Rica . My suggestion is to use the north coast crossing of Sixaola for one passage so you can explore the Bocas Del Toro region . The cross mountain highway is great for scenery but pavement condition on the north face is highly variable after wet season land slides .
On the south side of the mountains you have choice of A the busy PanAm crossing at Paso Canoas or B the calm piedmont town crossing at Rio Sereno which will bring you to San Vito CR by fine paved highway in green tropical country .

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