I’m going to give it a whirl soon. A loop from Pitlochry, Loch Rannoch, Glen Lyon, Bridge of Orchy, WHW to Fort William, EHW to Loch Laggan, Culra Bothy, Dalwhinnie, Pitlochry.
I did it in a day last year, albeit, it was a day with a relentless headwind, about 0 degrees and snowing in parts, so I used the road a bit to short cut some sections. Started out nicely, but I was being battered with hail/snow showers at regular intervals in the second half. A nice big day out with good scenery but no real interest in the riding – lots of firetrack etc. No doubt I’d have enjoyed it more in better conditions and with the usual prevailing south westerly.
I have the GPS plots below if they might be of interest, although I used a lot of road in the second half (I was cold, wet and thought I was running late for my train home, although ended up being rather early). The first half is fairly accurate to the route. There is a bit of a detour off Loch Laggan too I think, due to forestry work at the time.
Bear in mind that it is not signposted, so a Garmin 800 or similar might be useful unless you want to check a map periodically.
TBH, I’m not convinced that it’s a very good route. When I did a Fort William – Moray Firth ride via Aviemore I knew I wanted to do the Corrieyairick as part of it and also to incorporate some of the old Wade Road East of the A9 so just made up my own route.