j3 competition kosmic Manual page 9

8. Tire Pressures
Class
Cadet
100cc Junior
TaG Senior
ICA
125cc/KZ/ICC
General rule: The higher the tire pressure is started out at, the quicker the tire will reach
its optimum pressure. This will also cause the tire to have a decreased window of
effectiveness. Therefore, in longer races it is better to start off at a lower pressure giving
the tire a longer window of optimum operating time.
9. Axle Chart and the effectiveness
Axles are very much talked about regarding tuning a Kart and rightfully so. OTK
produces six (6) axles for the 100cc category and five (5) for the 125cc gearbox category.
OTK Type 'N' is the standard axle and medium stiffness for the entire range. This axle is
also what each chassis comes standard with from the factory.
Which is the best axle to use when? Generally the consensus is that a softer axle (Type
U) will free the chassis letting it operate more freely around the track. This may be true
in some instances but typically not with the OTK material. Typically it is recommended
to use a harder axle (Type H or HH) when the grip levels increase. Softer axles are
recommended more for use when the grip levels are low. Why is this true? This holds
true mainly due to the fact the chassis are made of soft 30mm tubular steel. With a soft
chassis and a softer axle you will essential create the tire to work more creating "Side
Bite" or the sidewall of the tire to rollover. This will cause the chassis to 'Hop' and
therefore lose its effectiveness throughout the race. Keep with the 'N' axle; we use this
axle 80% of the time and as the grip level increase the 'H' will work for your needs.
Remember that the axle doesn't simply work outside the chassis, it also creates balance
between the frame rails, and therefore, increased stiffness on your axle selection will give
the chassis more balance as well.
*Axle Chart provided on the following page
J3 Competition Inc. – Kosmic Owner's Knowledge Packet
Compound/Make
Bridgestone YHC
Bridgestone YHC
Bridgestone YHC
Bridgestone YJB
Bridgestone YJB
Cold
Vary 12.5psi / .85 Bar
Vary 12.5psi / .85 Bar
Vary 12.5psi / .85 Bar
Vary 11.5psi / .75-.8 Bar
Vary 11.5psi / .75 Bar
Hot
9 | P a g e