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1 DEFINITION
A Group 2 lawn mower is a machine designed to cut grass for domestic purposes. In standard form it will be self propelled and roller driven but for racing it will have a towed seat.
In Group 2 you may either use a tuned engine as defined in 2 or an untuned engine as defined in 3.
See General Rules and Regulations and remember, if it doesn’t say you can do it, you can’t do it.
2 TUNED ENGINES
1.The upper horsepower limit (manufacturer’s rating) is 6hp and must have been originally offered by the manufacturer
2.The engine must be retained in its original position, or if an optional engine is used the crankshaft must be on the original axis.
3.The original block, crankcase and cylinder head must be retained.
4.The fuel for any engine must be ordinary pump fuel and be free from any performance / power increasing additives.
5.Should the entrant be in any doubt about the legality of his/her engine, they must consult the race committee.
3 UNTUNED ENGINES
1.The upper horsepower limit (manufacturers rating) is
A - 8hp, 4 stroke with overhead valves or B - 10hp, 4 stroke with side valves
2.Standard engines may not be modified or ‘blue printed’ in any way apart from the following:
•The exhaust pipe and silencer may be altered or changed.
•The governor may be removed or disconnected.
•No other alterations or modifications are allowed.
3.Should a rebore become necessary because of wear or damage, only the manufacturers standard or ‘oversize’ available piston and rings etc may be used as replacements.
4.The fuel for any engine must be ordinary pump fuel and be free from any performance / power increasing additives.
5.Should the entrant be in any doubt about the legality of his/her engine, they must consult the race committee.
DRIVE
1.The original type of drive i.e. belts, chains, gears or whatever, must be retained. Pulleys, gears etc, may be changed for bigger or smaller ones to alter ratios. If the drive was originally through a chain case on the side of the mower, it must continue to be through the chain case on the original side.
2.A Gearbox may only be used if originally fitted, then it must be standard and to the original specification. No variable transmissions i.e. no torque converters or variable pulleys are permitted.
3.Drive rollers must be in their original position and must not be less then 2/3 (66%) of their original width. Rollers may be modified to improve grip but this will only be by the addition of rubber, the maximum tread depth must not exceed 3/8” (10mm). Securing bolts (holding the rubber to the roller) must not protrude above the depth of the tread.
5 SAFETY
1.Mowers must be fitted with an automatic throttle closing device, which will work whenever the driver’s hand or foot leaves the throttle control. Two independent throttle closing devices to be used, e.g. two springs.
2.An ignition cut out, which will work under any circumstances should the driver loose contact with the mower. A noose around the driver’s wrist is not acceptable. The cut out connection must be positively fastened both to the driver and the cut out and must not extend further than 3 feet.
3.No sharp edges or protrusions are allowed.
4.A braking system must be fitted.
5.Any part of the exhaust pipe that could be used as a grab handle must be wrapped or guarded.
6 CHASSIS and GRASS BOX
1.Handle bars and controls may be lowered and altered, and the overall profile must remain that of the standard lawn mower.
2.Grass boxes where originally fitted must be retained and securely fastened. They must be of the original type and as nearly as possible in the original position, except that some grass boxes may have to be fitted slightly lower than standard. If it becomes necessary to replace the grass box, the replacement must be as wide as the mower side plates and it must look, as closely as possible, like the original grass box.
3.When the mower is stationary, the grass box should rest on the ground. With the driver seated and the handle bars pulled back into the racing position, the bottom of the grass box must not be higher than 3” (76mm) from the ground.
7 TRAILER and SEAT
1.The design of towed seats is free. They may be lowered and the choice of roller or wheels is optional.
2.The drivers foot rests may be moved from the tow bar to the back of the mower but may not be any further forward. They must not protrude outside the side plates.
3.Trolley wheels must be guarded to avoid contact from the rear.
4.The overall width of the trailer (to the outside edge of the rear tyres) must not be more than 6” (152mm) wider than the mower (measured between the side plates).
5.The actual seat may be changed or modified but the back rest may not be higher than the driver’s shoulder blades.
6.Towed seats must be secured to the mower by two separate linkages. The first is, as on a normal mower, to pull the seat along. It can be modified or replaced as long as it is strong enough to satisfy the scrutineers. If a nut and bolt is used at the end, holding the linkage to the mower, then the nut must be secured by a split pin or similar. The second linkage is primarily a safety one which will allow the driver to retain control, at least until the mower is brought to a halt, should the main linkage break. This 2nd linkage must not inhibit the mower to seat movement through any of the 3 planes: -
•Side to side (as in steering)
•Pulling back and pushing forward of handle bars (lifting and lowering of the grass box except for the 3”)
•Rocking from side to side (either side of the mower can be lifted at least 3” without the seat lifting in standard or racing position
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