McWilliams led after one lap of the Supertwin race on Thursday

The popular Kawasaki racer briefly led the Supertwin race before coming off at Magherbouy chicane on the second lap.

"I am just that disappointed, I feel like throwing the towel in," he said.

"We can see that the bikes are really good and they can run at the front so we will just sit down and have a think about it."

The former Grand Prix winner has claimed victory in the Supertwins twice at the famous Triangle Course, in 2013 and 2015.

After one lap on Thursday, McWilliams had weaved his way to the front despite starting on the third row of the grid.

"I am surprised that I was able to get to the front," he admitted.

"There are a couple of really quick guys out there with many more laps under their belt than I have so I have got to take the positives out of it."

The second Supertwin race is set for Saturday, although McWilliams hinted that he may not feature on the new KMR Kawasaki.

"I have no idea what I am going to do, whether I am going to ride or not," he said.

"Really it depends on whether or not I can get back to where I was on the other set-up, if that's possible then there is a chance I probably will."

Paton racer Stefano Bonetti went on to win the Supertwin race, becoming the first Italian victor in the 90 year history of the North West 200.