From KLL to Luibeilt is good LR track. From Luibeilt to Creaguaineach is 90% portage on the Staoineag side of the Uisghe Labhair, the route I always take. From Creaguaineach to the YH is 100% rideable the old LR track has been renovated. No technical fun here – either portage or Landrover track.
Options to make a loop are limited – I presume you intend returning by the same route. If you go from Loch Treig towards Chairain you pick up a technical track at the dam, but the portage is crap.
Disclaimer – this was typed without reference to a map so I apologise for misspellings.