Supermarket worker Loganathan Thillaiyampalam, 63, of Caldecott Crescent, Whitchurch, admitted causing serious injury by dangerous driving.
Judge Rhys Rowlands at Mold Crown Court imposed a 21-month prison sentence, suspended for two years.
Thillaiyampalam was also banned from driving for three years, with an extended test, and fined £2,000. He also has to pay £910 in costs.
The court heard that Thillaiyampalam had been driving a Honda CRV on the A483 between Newtown and Welshpool on April 22, last year when, near Garthmyl, he overtook a vehicle towing a livestock trailer.
Judge Rowlands said it was “plainly unsafe” to do so. Although there was no suggestion of excessive speed, he carried on when the motorbike headlight could be seen.
“It was entirely obvious this was a dangerous manoeuvre. You should have aborted the manoeuvre, instead you carried on,” the judge said to the defendant.
Brian Treadwell, prosecuting, said Thillaiyampalam was travelling at about 47mph and the teenager on a Yamaha machine was knocked unconscious.
The victim also suffered fractures, lost flesh and was in hospital until May 4.
At the point of the impact, the defendant was prohibited from being on that side of the road, counsel added.
Judge Rowlands told Thillaiyampalam the injuries “could have been very much worse, fatal even”.
He said: "The collision could so easily have been avoided if you had shown a little more patience and better judgement. It was entirely your fault.”
Defence barrister Simon Rogers said : "The defendant made a huge error of judgement and sadly that’s had devastating consequences for the victim.”
Mr Rogers said that at the time of the crash his client had no previous convictions but there had been a subsequent drink-drive conviction.
He said Thillaiyampalam was remorseful, he was hard-working and his wife had ill-health.