The replacement utility motors coming from China have caught not only the go karting world by storm but have also found a home in custom minibikes, minibike drag racing, sailplanes, backyard race tracks, alky burning bar stools, speed boats, and any other project one can dream of building. Rumor has it that, on occasion, one even finds its way onto a cement mixer or log splitter, which just happens to be their intended use. You get 6.5 horsepower governed to 3900 rpm, low oil shut off, gas tank, air filter, and they’re ready to run with some gas and oil, for 99 bucks. And if that isn’t enough, some come with a warranty. When was the last time you bought a race engine with a warranty? Well, maybe it’s not a racing engine yet, but it doesn’t take much effort to get the clones ready.

Today’s clones are far more than just a cheap OHV utility motor. With dual main bearings, steel sleeves, forged cranks and aluminum heads, the potential for more power was too tempting for backyard and garage mechanics to resist. Until its introduction in the late 1980’s, there were very few economical alternatives to replacement motors in the power driven industry. Briggs and Stratton, along with Honda, dominated the replacement motor market with Kohler, Yamaha and others playing smaller parts. The timing was right and, with a price tag under $100, it was simply too irresistible not to give the clones a try. It wouldn’t take long for the karting industry to jump onboard, increasing the demand and versatility. It’s simple and reliable design made it perfect for even the newbie’s wrenching ability. What father could resist being a mechanical hero and crew chief in their sons, or daughters’ eyes at the local dirt track? And seeing the smiles on your kids faces when they jump on that minibike or compete in and win their first kart race is priceless.

The cost of go kart racing has gone through the roof, and most would say this insane clone craze has come at the right time.Looking back at the last decade, I don’t believe anybody saw this coming at first. The major advantage of the clones is cost first and foremost. How about a complete parts inventory all for $99. These motors make rebuilds a thing of the past. A complete season of racing is not uncommon with no more than an oil change, clean air filter, and keeping up with loose nuts and bolts. And if wrenching and modifying is your passion, there are plenty of manufactures and suppliers that can fill your “stock appearing” or “open racing” needs with cams, roller rockers, stroker cranks, racing pistons, bigger carbs, stainless valves and a huge selection of billet parts. The major disadvantage for us racers would be the casted flywheel. Rated to 3900 rpms they can explode at levels above 5500. Kart racers realized years ago of the dangers of exploding flywheels. They can be lethal. But not to worry because company’s like ARC Racing and Raceseng have come to the rescue with billet aluminum flywheels that can safely take you to 9000 rpm’s and beyond.

Good or bad, you can’t help but get caught up in this growing frenzy that has brought back the entire family to kart racing. Not since the 70’s and the introduction of the Yamaha KT100, have I seen so much excitement about a new motor. The escalating cost of this sport has excluded many who, if given a chance, would love to have the opportunity to race. Having built a few Mac’s, Yamaha’s and Briggs in my day, I found myself torn between loyalty and just plain economics. So, casting my feelings aside like a good unbiased engine builder, I purchased my first Wren 5.5 horsepower clone at Pep Boys. It was red and that was 15 years ago. So, for well over a decade these clones have become a big part of my racing career.

This story has been repeated throughout, not only the United States, but also many parts of the world. Organizations like AKRA have jump on board with rules and national events giving birth to “Big Money” for the winners. U.S. manufactures and producers have come forth with all kinds of modified parts so you can race 6.5 horsepower at 3900 rpm’s on gas or 20 plus horsepower alky burning, 9000 rpm screaming torque monsters. From the dirt trackers of the south and northeast to the streets of LA and everywhere in between, many are finding a use for these little “diamonds in the rough.”

within 25 degrees during the test. The Dupor made 8.78 horsepower at 4700 rpms and maximum torque of about 12 ft. lbs. was achieved at 3300 rpms. The air/fuel ratio was about the same as the Greyhound showing a lean condition through most of the run in the range of 15. Like the Greyhound, it also leaned out more as the horsepower dropped off at 4700 rpms. Since they both have Ruiing carbs this should come as no surprise. Horsepower equaled torque at 5300 rpms. The Dupor seemed to have a slight advantage in early torque, but the horsepower curve was almost identical to the Greyhound throughout the run. The Greyhound horsepower did drop off sooner in the 4600 rpm range giving another slight advantage to the Dupor.

In summary, the Dupor performed very well and held up without failure. It appeared that the Dupor has a slight advantage over the Greyhound with respect to early and maximum torque but the horsepower curve was too close to call. In all fairness, one must consider some error factors in the data of the different runs to come to an accurate conclusion.