I came across a website which has some solid builds for each course:
https://m.imgur.com/a/mfqkOJust a quick note, don't worry about boosting on any of these races. If you don't win the first time try again with the same build as there is a bit of RNG involved. Always be ready to press the circle button so you don't fly off the course.
If for some reason you cannot view the above webpage:
*** Spoiler - click to reveal ***Introductory Race:
Cool Striker
Slick Tires
Balanced Frame
Speed Motor
Regular Gears
High Speed Battery
Little Racer Cup:
Cool Striker
Slick Tires Plus
Speed Frame Plus
Speed Motor Plus
Regular Gears Plus
Regular Battery
Rookie Race:
Cool Striker
Slim Tires Plus
Speed Frame Plus
Speed Motor Plus
Balanced Gears Plus
Regular Battery
Beginner Cup:
Cool Striker
Spiked Tires Plus
Speed Frame Plus
Speed Motor Plus
Balanced Gears Plus
High Capacity Battery
Amateur Cup:
Cool Striker
Extra Spiked Tires
Extra Metal Frame
Extra Speed Motor
Extra Balanced Gears
Regular Battery
Standard Cup:
Cool Striker
Extra Slick Tires
Extra Metal Frame
Extra Speed Motor
Extra Balanced Gears
High Capacity Battery
Side Stabilizer
Intermediate Cup:
Cool Striker
Extra Slick Tires
Super Rocket Frame
Super Speed Motor
Boost Gears Plus
High Capacity Battery
Medium Suspension
Advanced Cup:
Cool Striker
Super Slick Tires
Super Speed Frame
Super Speed Motor
Boost Gears Plus
High Capacity Battery
Medium Suspension
Pro-Am Cup:
Cool Striker
Ultra Slick Tires
Ultra Speed Frame
Godspeed Motor
Extra Boost Gears
High Capacity Battery
Medium Suspension
Elite Cup:
Cool Striker
Ultra Slick Tires
Ultra Rocket Frame
Godspeed Motor
Extra Boost Gears
High Capacity Battery
Heavy Suspension
Expert Race:
Cool Striker
Ultra Slick Tires
Ultra Rocket Frame
Godspeed Motor
Super Boost Gears
High Capacity Battery
Heavy Suspension
Master Cup:
Cool Striker
Ultra Spiked Tires
Ultra Rocket Frame
Godspeed Motor
Ultra Boost Gears
High Capacity Battery
Heavy Suspension
Champion Cup:
Cool Striker
Ultra Spiked Tires
Ultra Metal Frame
Godspeed Motor
Ultra Boost Gears
Regular Battery
Heavy Suspension
Bumper Plate
2005 King of Speed Cup:
Cool Striker
Ultra Slim Tires
Ultra Metal Frame
Ultra Godspeed Motor
Ultra Boost Gears
High Capacity Battery
Heavy Suspension
Bumper Plate
Sub Story 56 (Beat Fighter):
Golem Tiger
Super Soft Tires
Super Rubber Frame
High Torque Motor Mark II
Goodspeed Gears
Regular Battery
Side Stabilizer 2.0
Heavy Suspension
Bumper Plate
Sub Story 56 (Beat Takuma):
Golem Tiger
Super Soft Tires
Rubber Frame Plus
Godspeed Motor
Super Boost Gears
Regular Battery
Heavy Suspension
Sub Story 50 (Win the Present):
Golem Tiger
Ultra Spiked Tires
Ultra Balanced Frame
Godspeed Motor Mark II
Ultra Power Gears
High Speed Battery
Side Stabilizer 2.0
Heavy Suspension
For a list of part locations:
https://gamefaqs.gamespot.com/pc/241146-yakuza-kiwami/faqs/7...If you do not have enough Yen to purchase required parts you can grind it out at the Coliseum which is probably the best way to make money in the game. I also strongly recommend equipping the "Socks of Fortune" as early as possible, this item can be traded for 10 CP from Bob Utsunomiya (the clown guy on Tenkaichi Street Gate.)