A mother and her partner have been jailed by the South Australian Supreme Court after a four-year-old girl died when repeatedly forced to ride a motorbike.

The girl's terrified attempts were filmed by her mother, Ashlee Jean Polkinghorne.

Polkinghorne, 22, and her partner, Benjamin Robert McPartland, 28, will serve at least four years in jail for manslaughter by criminal negligence.

The woman's daughter, Chloe Valentine, was repeatedly put on a 50-kilogram motorbike in the backyard of the family home at Ingle Farm in January 2012 and filmed crashing into objects.

The court was told the girl suffered severe injuries and was so swollen and bruised when taken to hospital that some other family members could not recognise her.

During sentencing, Justice Trish Kelly said the motorbike was far too big for Chloe.

"She could barely touch the ground and could not stop the bike without falling off it," the judge said.

"Chloe weighed 17 kilograms at the time of her death, the bike weighed over 50 kilograms, nevertheless that did not stop you from forcing Chloe to get on that motorbike on multiple occasions in the three days leading up to her death."

She said the small child was extremely fearful of McPartland, and Polkinghorne had laughed as the girl fell from the bike.

"The four-year-old would never had dared say 'no'," the judge said.

Sorry, this video has expired Couple jailed over 4yo's death riding backyard motorbike

Justice Kelly said Polkinghorne had been prepared to let her child die rather than exercise any proper parental responsibility.

"You were Chloe's mother ... you were the one who was closest to her yet you gave her no medication, you didn't take her to a doctor, even after you knew something was gravely wrong," she said.

"All you did was Google on the internet and go on smoking marijuana, to which you were then addicted."

She criticised the pair's failure to call an ambulance when Chloe became unconscious, saying Polkinghorne and McPartland did not seek medical help for hours after the girl became unconscious and only did so when she had stopped breathing.

"You failed to get her any medical treatment after the emergence of bruising and injuries," Justice Kelly said.

"Even after Chloe was rendered unconscious you waited another eight-and-a-half hours while the child lay in a semi-vegetative state before either of you made a call for assistance."

Justice Kelly also criticised Polkinghorne and McPartland for their contradictory statements and said because neither had given evidence during the trial she found them equally to blame.

"Each of you has expressed conflicting versions of the circumstances that led to her death," she said.

Justice Kelly said the jail term had to reflect that a human life had been lost.

She said Chloe had been a defenceless and vulnerable child.

Polkinghorne was jailed for eight years and must serve at least four years and nine months.

McPartland was jailed for seven years, with a non-parole term of four years and two months, reflecting his earlier guilty plea and efforts to rehabilitate.

There were cheers in the courtroom as the sentence was passed and someone yelled: "Now you know how Chloe felt."

A member of the family, Tricia Foord, told reporters outside the court that child welfare authorities should have removed the girl from her mother.

"I think when people are reporting to Families SA over 100 reports and they don't seem to do enough and remove the child ... that's all we wanted, remove the child," she said.

"Plenty of families wanted to take that child and put her in a safe place, that didn't happen."

Supporters of the four-year-old victim wore yellow ribbons to the sentencing, saying it had been Chloe's favourite colour.