1. Fast Motorsports & Cloud 9 Racing
Karting 101
Jeff Cloud
Erik Frank

2. Types of karts Sprint kart Sit up Weight ~ 350 lbs
Engines - 2 or 4 stroke
100cc Yamaha, Rotax
80 – 125cc dirt bike
Briggs & Stratton
HP - 8 ~ 40+
Top speed ~ 100 mph
125cc Shifter Kart

3. Types of karts Enduro kart Laydown Road racing only Engines - 2 stroke
Piston port (KT100 Yamaha, TKM)
Reed/Rotary (DAP, Parilla, Komet, PCR)
Top speed >100 mph
Laydown Enduro Kart

4. Types of karts Super kart Wings Weight ~ 450 lbs Engines - 2 stroke
Rotax 257
Motocross bike (CR 250, YZ 250)
250cc Twin: Rotax 256, Yamaha TZ-250 (G.P. derived)
HP (singles) 90+ (twins)
Top speed ~ 150 mph
Super Laguna Seca

5. Kart Engines 101 Yamaha KT100 100cc Reed Rotax Max FR125 SGM F/E
YZ-125
Rotax 257

6. Racing Formats Sprint Racing Tight, twisty tracks < 1 mile long
Speeds limited to <75 mph
Short races (typically laps)
Very quick pace
Very physical
Texas Sprint Tracks:
Hill Country Kart Club
(New Braunfels)
North Texas Karters (Denton)
Gulf Coast Karters (Houston)
Waco
NTK – Denton, TX

7. Racing Formats Road Racing Run on large road racing courses
Longer races (usually 30 minutes)
High speeds - over 100
mph for some classes
Large fields
Regional Road Race Tracks:
Texas World Speedway (College Station)
Motorsport Ranch (Cresson)
Oak Hill Raceway (Henderson)
Hallet Motor Racing Circuit (Oklahoma)
Typical 125cc Grid
Oak Hill – Henderson, TX

8. Kart Racing Organizations

9. Kart vs. race car handling
Karts
Very quick steering response
Short wheelbase and wide track
Direct acting steering linkage (typ. 1/3 turn lock-to-lock)
Must be smooth to achieve quick lap times
Cars
Slower steering response
Longer wheelbase vs. track
Heavier
Smooth is still fast

10. Kart vs. race car handling
Brakes
Sprint kart brakes only on rear
125cc Shifter karts and Super karts also have front wheel brakes
Approx. ~2G deceleration is possible
Front Brake assy (Brembo)
Rear brake assy (Brembo)

11. Kart chassis setup
Kart setup seems to be contrary to conventional auto practice
Stiffen chassis and increase weight transfer for low grip track
Soften chassis and decrease weight transfer for high grip track
Must lift inside rear tire to go around corner
Solid axle wants to go straight
King Pin Inclination (KPI) and caster cause inside front wheel to drop and outside front wheel to rise which tilts kart to outside of turn and lifts inside rear wheel (Jacking Effect)
Caster and front track width (offset) alter jacking effect

12. Kart Cornering 101
Look!

13. Camber/Caster Orientation
Karts will never have zero caster, typically negative 15 degrees
Karts typically run +/-1 degree camber (will go more negative as chassis flexes)

14. Kart Chassis Setup Center of Gravity Driver is largest mass
Location has critical effect on handling
Raising driver increases weight transfer
Low grip track - higher seat position
High grip track - lower seat position
Raising ride height also increases weight transfer

15. Kart Chassis Setup Track Width Adjustments Tire Pressure
Increase Rear track: (decreases rear grip)
Increase Front track: (increases weight transfer)
Up to a point!
Tire Pressure
Higher pressures
 Increases temperatures
 Increases grip

16. Safety Helmet Gloves Racing shoes Neck Collar
Safety is Important!
Helmet
Gloves
Racing shoes
Neck Collar
Suit or heavy jacket and long pants
Not fireproof, abrasion resistant
Typically made of Cordura/Nylon

17. Data Acquisition Measured parameters Aim Sportsystems EVO 3 Lap time
Sector times
RPM
Speed
Water temp
Exhaust gas temp
Lateral / longitudinal G
Steering position
Throttle position
Tire Temps
Etc…
Aim Sportsystems EVO 3

18. Data Acquisition Analysis software versatility: Eliminate guessing
Solid foundation for setup changes
Driver training / consistency
Lap time comparisons
Kart behavior at specific locations on track
Engine performance
Engine tuning aid
Horsepower calculation
Alfano Pro D/A
Handling evaluation
Oversteer/Understeer (driver or kart induced)

19. AIM Sportsystems Race Studio

20. AIM Sportsystems Race Studio

21. Kart Engine Tuning Overview
Intake
Cylinder porting
Ignition
Exhaust
source:

22. Kart Engine Tuning - Intake
Mixture setting is critical
Carburetor adjustments:
Main Jet
Needle
Fuel system (delivery)
Reed cage setup
reed material
aftermarket options
Keihin PWK Carb
V-Force Reed Cage

23. Kart Engine Tuning - Porting
Exhaust Port timing is important
Higher ports  “More top end”
Lower ports  “More torque”
Compromise between port area and piston/cylinder life
Auxiliary “Boost”
Ports
Inlet Ports
(piston port)
Exhaust Ports
Transfer Ports

24. Kart Engine Tuning - Ignition
Static Advance
Stator setting on crankshaft
Dynamic Advance
Achieved by CDI box (on shifter engines)
Digital Programmable systems available
CDI Box
Harness
Coil
Spark Plug Boot
Rotor/Stator

25. Kart Engine Tuning Overview
Exhaust – Pipe Selection
Determines Operating Powerband
Experimental Pipe setup – YZ 125

26. Dyno Testing Optimization of YZ-125 for Roadracing Porting
Cylinder head
Piston
Intake
Ignition
Exhaust

27. Dyno Testing
~3 HP gain
~10 HP gain

28. Road Atlanta - Nov. 2002 12 turns – 2.54 miles
Substantial elevation changes
5000 ft. Long “straight”
250cc Super kart lap time: 1:34 (97.2 mph avg!)

29. Wrap-Up
Questions?
Show and Tell