Ian Hutchinson had to forfeit his Superstock times from Tuesday's North West 200 qualifying session after his bike was found to be using non-compliant fuel.
Three-time winner Hutchinson was 11th fastest in practice at 117.97mph.
But a statement issued after Tuesday's session said organisers of the event "stipulate the use of a control fuel only in each machine".
Hutchinson - riding for Honda Racing - is still able to qualify on Thursday if he completes the required number of laps.
Speeds and lap times from Tuesday and Thursday's practice determine grid positions for the two Superstock races.
North West 200 Tuesday practice times as Alastair Seeley goes fastest in Supersport class
Meanwhile, Bradford rider Dean Harrison was fastest on the Superbikes during Tuesday's qualifying.
Harrison set the fastest Superbike lap of 121.21mph, ahead of Michael Dunlop and Alastair Seeley.
Seeley led the first Supersport session with Peter Hickman topping Superstock practice and Jamie Coward the fastest in Supertwins.
North West 200 TV coverage 2019, live stream and radio information
Hickman's best Superstock lap was faster than Harrison's Superbike mark as produced a mark of 121.448 mph.
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