If you're looking to earn more diamonds in MotoGP Championship Quest without purchasing them, here are two main methods:

1. Collect Daily Rewards:
Make sure to play the game every day to receive the Daily Login Reward. By being a loyal player and playing consistently, you can earn 70 Diamonds and 19,000 Coins per week.

2. Enter Tournaments:
Participate in tournaments within the game to have a chance of winning diamond prizes. Keep an eye out for tournament events and compete to earn additional diamonds.

To optimize your coin earnings, consider the following strategies:

• Wager before each race: By placing bets before races, you can potentially increase your coin rewards if you win.
• Collect sponsor rewards: Make sure to collect all your coins daily from your sponsors within the game.
• Watch ads: Take advantage of the option to watch advertisements at the end of each race to earn additional coins.
• By utilizing these methods, you can enhance your diamond and coin earnings in MotoGP Championship Quest.