Michael Dunlop will sit out Thursday evening's Supertwin race at the Relentless International North West 200.
Dunlop had entered the event, which is being held for the first time on the 8.9-mile 'Triangle' circuit this week, on a Kawasaki ER6.
However, he has been forced to shelve his plans and will instead concentrate on the feature classes at the iconic international road race in Northern Ireland, the Superbike, Superstock and Supersport events.
“I won't be riding in the Supertwin race because we just don't have the time to get the bike sorted,” said Dunlop.
“It means I'll be going to the TT without having ridden the bike before, but there's nothing we can do about and we'll just have to get on with it.”
Dunlop only finalised his plans for 2012 in March and had little track time on his stable of machines prior to the opening Irish National road race of the season at the Cookstown 100 last month.
He claimed his first victories at Tandragee last weekend, winning the Supersport and feature Superbike races as he begins to get to grips with his new Hunts Motorcycles/McAdoo Honda Superbike and his Ard Na Mara Homes/McAdoo Suzuki GSX-R600.
Dunlop is among the key contenders at the North West 200, when he will also compete in the Superstock races on a Kawasaki ZX-10R as he aims to complete a clean sweep of victories in the class at the big international races following his wins last year at the Isle of Man TT and Ulster Grand Prix.
Thursday's Supertwin race is part of a revamped programme during NW200 race week, with a Superstock race also being held following daytime practice on Thursday, when all the top guns will be out in force.
In the Supertwin race, KMR Kawasaki team boss and rider Ryan Farquhar holds a strong hand with ex-Grand Prix winner Jeremy McWilliams making his racing debut at the North West in the event and 12-times winner Michael Rutter also riding in the KMR colours along with young prospect Jamie Hamilton.
Honda TT Legends ace Simon Andrews will ride a Kawasaki ER6, with entries also received from James Hillier, Ian Lougher, Olie Linsdell, Paul Shoesmith, Adrian Archibald and John Burrows.