General
Externally the engine should resemble a standard Honda or Clone GX model as close as these regulations permit.
No specific coating procedures are allowed on any internal or external surface of the engine except as specifically permitted herein.
The fasteners on the engine may be drilled to allow for lock wiring. A thread recovery procedure is acceptable providing that the system and replacement fixing are of the same size or pitch to the original and therefore offer no mechanical advantage over the original fixing.
Definitions
The term “standard, unmodified component” means that the component has not had its substance altered in any way. It has had no material added or removed and will be of the same original material. Where appropriate, the marks from the manufacturer’s processing or machining will still be present, except as specifically permitted herein.
Engine Type
The only eligible engines are Honda GX160/GX200 or Honda Clone.
Engine Components
Fuel Tank
- The original fuel tank must be removed and replaced with a suitable engine cover.
- A standard floor-mounted tank should be used instead.
- An extra loop of fuel pipe may be used as a return feed to the tank.
- Inline fuel filters may be fitted.
- Fuel pump type is free.
Fuel
- All fuel used shall be “Pump Fuel” as freely available at roadside filling stations.
- Fuel samples must be available for Scrutineers when required in accordance with the regulations.
Exhaust
- The exhaust must be GX160/GX200 type (see Appendix A).
- Modification is free but must comply with noise regulations and general kart specifications.
Carburettor
- Must be a GX160/GX200 type.
- The black plastic insulator between the carburettor and cylinder head should remain in place.
Additional Regulations
Air Intake Filter/Silencer
- The Honda-style lower part of the air box should be in place.
- No velocity stacks/air filter adaptors that fit directly to carburettor intake allowed.
- An air filter/silencer must be fitted – choice of air filter is free.
- No turbocharging or supercharging of the incoming air is permitted, including “forced air” induction.
Spark Plug & Cap
- The spark plug and cap are not restricted.
Engine Bodywork
- Bodywork and ducting may be modified.
- Pull cord mechanism and on/off switch must be fitted and fully operational.
Valve Gear
- Roller rockers (see Appendix B) are not permitted.
Cylinder Head
- No restrictions to combustion chamber size, inlet/exhaust ports/tracts, valve guides or seats.
Piston
- Must be Honda/Honda clone industrial type with two compression rings and oil control ring.
- Rings must be in place and not fixed.
- Piston shape may be modified.
Connecting Rod
- The original con rod may be modified.
- A billet aluminium rod with replaceable shells may be used.
- Must not be modified to increase or change the stroke length.
Crankshaft
- The governor gear may be removed.
- Cam gear wheel position is not restricted.
- Crankshaft end float and regrinding of the big end journal is permitted.
Flywheel & Cooling Fan
- No restrictions.
- Balancing permitted, but lightening is not (unsafe part risk).
Ignition Coil
- Must be the standard unmodified type (not including ignition lead).
- Ignition timing is not restricted.
Camshaft
- Not restricted.
Crankcase
- Can only be modified by removal of governor mechanism and oil alert (if fitted).
- Holes left must be sealed.
- Cylinder head mating face may be altered.
- Camshaft oil way may be enlarged.
- Grinding at cylinder base to clear cam lobes allowed.
- In all other respects, crankcase must remain standard and unmodified.
- No sleeving or material change to the cylinder bore permitted, but honing is allowed.
Crankcase Side Cover
- Camshaft oil way may be enlarged.
Engine Fixtures
- All nuts, bolts, and studs may be changed or replaced for improved quality.
Gaskets
- Not restricted.
Clutch
- Must be a dry, air-cooled centrifugal clutch of the following types:
- Normal
- Premier
- Horstman
- Magnum
- Max Torque
- 1600 or 400 series
- Must be in standard form except for clutch springs (which are not restricted).
- Must be incapable of adjustment in position on the engine.
Appendix A
For the purposes of this document, “GX160/GX200 type Exhaust” includes:
- Blackthorn Exhaust
- DEP GX160 Cadet Exhaust
- DEP GX200 Extreme Exhaust
Appendix B
For the purposes of this document, “Roller Rockers” are defined as items having or including a roller tip.
Gearing
Gearing will be open.
Tyres
Tyres must be either:
- Dunlop SL1
- Bridgestone YDS
No wet tyres are allowed.
Weight
Minimum combined weight of driver and kart: 185kg
