Here is the full list of all 50 Moto Racer 4 achievements.
Win 100 races online
Win a ten-player online championship
Win a ten-player online game
Make 100 online opponents fall down
Play a ten-player game
Do a 250-meter drift
Do a Flip + Trick combo
Do a double flip
Do a 10-turn donut
Win the 3-3 challenge without using the turbo
Unlock 165 stars
Succeed 55 challenges
You knocked down 100 riders with swerves
Unlock the eleventh chapter
Succeed chapter 5
Finish a private online game
Succeed all the slalom challenges with 3 stars
Win the 9-3 challenge with a Gold performance
Finish a race 10s ahead of your nearest rival (single race - 'God' difficulty)
Ride on a truck's trailer
Land on an opponent and make him or her fall down
Upgrade the T.U.R.B.O on Jody and Saul's bikes to the max
Successfully perform 200 T.U.R.B.O landings
Successfully attempt 50 perfect landings in one race
Do 3500 wheelies
Upgrade Wrench and Bolt's bikes to the max
Reach a total of one hour in mid-air
Score more than 5 000 000 style points
Reach a total of 500,000 style points in one race
Reach a total of 180 seconds of slipstreaming during a race
Do a wheelie on the Great Wall of China
Customize Stella to the max
Win the 6-2 challenge with a Gold performance
Brush against vehicles in traffic 300 times
Successfully attempt 200 orange T.U.R.B.O boosts
Reach a total of 150,000 style points in one race
Do a 5-second burn out… and win!
Reach a x10 style combo
Do 250 wheelies
Reach a total of 50,000 style points in one race
Perform a whip on a dirt bike
Do a trick
Keep your light trail for 120 seconds
Succeed a challenge
Do 200 swerves
Score more than 800 points with a single trick
Win all races in the 6-5 Championship with Amund
Score 3000 high-speed points in one go
Find all the shortcuts in the game
Move from one bridge to another over Spider Gorges