Lawn Mower Racing Mania – Which Class is for You?

Have you got lawn mower racing mania?  If you do, which class is for you?  Lawn mower racing is divided into several different classes or divisions. It is wise to do some research before deciding which class is right for you. Below is a quick overview of the various divisions and the subtle differences between the various classes. Note the slight differences between the major sanctioning bodies.

ARMA – American Racing Mower Association Divisions:
The American Racing Mower Association has several divisions.  There is a lawn mower racing class for every level of interest, budget, and skill.

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ARMA-Kids Stock, Adult Stock:
This is an entry-level class lawn mower racing designed for the novice with a low initial cost.
• Governed engine
• factory stock wheelbase
• stock front rims
• stock rear rims
• “as manufactured” original parts only.

ARMA-Kids Super Stock, Adult Super Stock:
These racing lawnmowers are slightly quicker than the factory stock; however, it is still a good entry level class.
• Governed engine 3650 RPM, single cylinder VIB or OHV 465 cc and under, 15 HP and under.
• Factory stock, full size racing mowers, with a wheelbase of 39”.
• Front wheels are 6”. Front tires range from 13” to 15”.
• Rear wheels are 8”. Rear tires are 16”.
• Maximum tire pressure: 15 PSI.
• Modifications allowed include air cleaner, air filter, open exhaust.
• You may strengthen the frame and reinforce the inside of the rims.
• Mowers must have the original shifter mechanism.
• The maximum gear ratio is 8-1.
• Body must be factory stock complete with factory deck.
• Front spindles must be 5/8” minimum.

ARMA-Mini Sportsman:
This is a fun lawn mower racing class for those with a desire to build their own racing engines.
• Internal engine modifications are allowed.
• Engines are 4 stroke, valve in block, 8.5 HP and under, 19cu in and under.
• Chassis have a 34” minimum unaltered wheelbase.
• Front wheels are 4” minimum. Rear wheels are 6” minimum.

• Engines are valve in block, single cylinder 4 stroke, 8.5 HP and over.
• Chassis are 39” minimum unaltered.
• Mid engine frames are not allowed.
• Front wheels are 5” minimum.
• Rear wheels are 6” minimum and 8” maximum.

• Engines are single OHV and Twin Opposed VIB, 20 HP and under.
• Chassis are unaltered with a minimum wheelbase of 39”.
• Mid engine frames are not allowed.
• Front wheels are 5” minimum.
• Rear wheels are 6” minimum to 8” maximum.

ARMA-Super Sportsman:
The sportsman class is step up in speed and race ability. These are fun and fast.
• Engines are all overhead valve, 2 cylinder, 4 stroke, 25 HP and under.
• Chassis are 42” wheelbase.
• Unaltered factory frames.
• Front wheels are 6” minimum.
• Rear wheels are 6” minimum to 8” maximum.
Pro X mowers are equipped with true lawnmower racing engines. This is true lawn mower racing mania. Are you ready to travel 40 MPH on a mower? If so, this is the class for you.
• Engines are single cylinder 4 stroke with unlimited horsepower.
• Chassis are 42” maximum for a mid-engine mower and 45” maximum on pan style frames.
• Wheelbase may be shortened to a minimum of 37”.
• Mid engine frames have a maximum width of 15” and a maximum length of 48”.
• Front wheels are 4” minimum to 8” maximum.
• Rear wheels are 4” minimum to 8” maximum.
• Kart tires are allowed.
• Snow Hogs are allowed on the front end only.
• Tire stagger is allowed.
• Wheel offset is not allowed.
• Round tubing and chrome molly tubing are not allowed.

USLMRA – United States Lawn Mower Racing Association Racing Divisions
The United States Lawn Mower Racing Association series has very similar classes to the ARMA riding lawnmower racing series. One interesting division is the JP class for kids. What a better way to make this a family event than to introduce young drivers to the sport in their own venue. Look out Dad; you may be embarrassed when Junior passes you on the high side. There is one thing to keep in mind about kids and racing; they have no fear.

This class was established as an entry-level division for kid’s ages 10 to 15 years old.
• Chassis are full-size stamped steel frames with a minimum ground clearance of 4”.
• No mid-engine frames are allowed. Body must remain stock.
• Engines are 3650 rpm governed with a maximum of 15 horsepower.
• Open exhaust is allowed.
• Maximum gear ratio is 8:1.
• Front wheels are 5” minimum.
• Rear wheels are 5” to 8”.
• Rear tires are 16” maximum.
• Front spindles min 5/8” diameter.
• Steering may be reinforced.

USLMRA-Stock Class:
Just as the name implies, these racing mowers are just as delivered from the factory. Add your number and safety tether and go lawn mower racing.
• Engines are governed at 3650 rpm
• Factory-original parts or equivalent must be used
• Tires have a maximum pressure of 15 PSI.

USLMRA- IMOW Class: (International Mowers of Weeds):
This is a very unique lawn mower racing class for front engines only. Rules are highly regulated to maintain the close competition.
• Chassis are full size 39” wheelbase with a maximum width of 38”.
• The minimum ground clearance is 4” and the deck clearance is 2 ½”. Hoods must be hinged.
• Engines are completely stock and governed at 3650 rpm with a maximum of 15 horsepower.
• Exhaust may be open.
• Front wheels are 5” minimum.
• Rear wheels are 8” minimum.
• Maximum tire pressure is 15 PSI.
• Steering may be reinforced.

USLMRA – Prepared Class:
The prepared or modified class is split into various engine groups. These are fast racing mowers.
• The common factor is that the engine and drive train can be modified internally and are equipped with an open exhaust.
• Due to the high speed, the steering must be upgraded to rod-eye style linkage.
• Shock absorbers are not allowed.

USLMRA – Prepared A/P:
• Engines are 8.5 horsepower, 4 stroke, 19 cu in.
• Chassis are 34” wheelbase.
• Front wheels are 4”. Rear wheels are 6”.

• Engines are 12 horsepower flat head.
• Chassis are 39” minimum wheelbase. Mid-engine frames are not allowed.
• Front wheels are 5” minimum. Rear wheels are 8” minimum.

These are super fast for lawn mower racing, with speeds in excess of 40 MPH.
• Engines are over 12 horsepower and up to 20 HP, OHV single cylinder, and V-Twin engines.
• Chassis are unaltered 42” wheelbase. Mid-engine frames are not allowed.
• Front wheels are 6”minimum. Rear wheels are 8” minimum.

Strap your helmet on tight for a ride on a factory experimental lawn mower racing. With major modifications allowed, these mowers have tremendous acceleration and speed. You will think you are piloting a sprint car.
• Engines are single cylinder 12 horsepower to 14 horsepower, up to 465 cc.
• You may use an aftermarket clutch and torque converter.
• Open exhaust is allowed.
• Chassis have a maximum frame width of 15” and a maximum length of 48”.
• No round or chrome molly tube allowed.
• Steering may be reinforced, and you must use spherical rod ends.
• Kart tires are allowed
• Snow Hogs are only allowed on the front.
• Maximum wheel diameter is 10”.

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