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Product Code: 002


By Gary Costanza

Love ‘em or hate ‘em, you can’t ignore them any longer.

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.

In the late 90’s along with a few of my racing buddies we started using these imports in our backyards on tracks we built ourselves. Well, that grew and got out of hand when 4 old dads became 12 bumper pushing, rubbing-is-racing, ex stock car drivers. Then the neighbors starting coming over to watch; then we had a barbeque every race; and then we had rules. Then the police started showing up to keep the peace, but they just couldn’t help themselves and had to give it a go. Then we had a bigger track with no neighbors or police, and then we had lights and now we are a complete club that put on shows at many tracks.

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.”

Clones come with different names and in all different colors like red, blue, black, yellow, and white. The colors represent differentfoundries, importers, and manufactures and, even though most parts are interchangeable with the Honda GX160’s and GX200’s, they all differ in quality, design, and potential power output.

So the question becomes, which $99.00 clone is the best for your project or type of racing? It’s time we have them battle it out on a dyno and see what numbers best suit your needs. In order to do this, they will need to get a slight makeover before they face the instrument of horsepower truth. Each motor has had the governor removed, a new air filter, open exhaust, and main jetting change. I used a #85 main jet (box stock is usually #72) to correct for the better breathing. The open exhaust system was needed for my gas analyzer sensor. Also, these clones come with a cast flywheel and are rated to 3900 rpms from the manufactures so, even though we are going beyond that, I will stop the run as soon as power starts dropping off in order to keep things safe. Anyone who has seen an exploding flywheel knows what I’m talking about.

The first clone to face Dr. Dyno I purchased for $99 from Harbor Freight in New York. Weighing in at 28.4 lbs and 196cc, it’s blue and called “The Greyhound.” I would say this is the most popular of the clones. Every Harbor Freight across the country sells them. After a 30 minute break-in and facelift, our first contestant was ready to face the “Truth Giver.” The dreaded Dr. Dyno.

After a slow warm up to 275 degrees head temperature, the Greyhound produced 8.77hp at 4500rpm ungoverned and maximum torque was about 11.5 ft. lbs. at 2800 rpms. The air/fuel ratio leaned out a bit in the beginning, around 1000 rpms to 16. In this range the Titan clutch was still slipping. The clutch was set with a

stall speed of 2500 rpms. That would be expected with a carburetor

that doesn’t have an accelerator pump. It smoothed out in the 15 range and leaned out again at the end of the run around 4200 rpms as the power dropped off. This motor comes with a Ruiing carb and the results suggest it ran lean with the #85 jet. I would think that with a #88 or #90 main jet it would do better. Power started dropping off at 4500 rpms and torque equaled horsepower at 5200 rpms. With improved breathing and the jet change, the Greyhound produced over 2 horsepower more than manufacturer’s suggested rating, and produced 1300 more rpms at top end. Head temperature remained steady between 275 and 300 degrees.

In summary, the Harbor Freight Greyhound performed very well within its manufacture’s suggested range and handled even more without failure. The manufacture states 6.5 horsepower at 3600rpm. Our test motor, with the exhaust and carb modifications, did better, producing almost 8 horsepower at 3600 rpms. Not bad for a utility replacement engine.

Our next contender, from ARC Racing out of Albany, GA, cost $99.00 and weighs in at 27.8 lbs. It’s yellow and called the Dupor. It comes needing some assembly and does not have a gas tank, exhaust system, or air filter. Like the Greyhound, it comes with a Ruiing carb. It does not have a low oil sensor. The lack of these parts would explain the difference in weights. This clone appeared

to be more versatile for the racing crowd, but not so much for utility replacement. The same jet change, exhaust, and air filter

were installed for this Dyno test.

After a 30 minute break-in and cool down, the motor was ready for its bout with Dr. Dyno. Again, with a warm up to 275 degreeshead temperature, it remained

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.

There is another popular yellow clone that’s imported by Jimmy

Simms out of Jennings, Florida called the Ducor. At the time of this article, it

too was $99. Unlike the Greyhound and Dupor, the Ducor comes with a Huayi carb. This motor gave birth to what us cloners call the BSP class or Box Stock Project. Although all 3 clones in stock form qualify as a BSP, the Ducor was imported for just that reason. Chances are you won’t find this one on a cement mixer or tiller. Check with your local track rules to be sure which clone is allowed. Like the Dupor, the Ducor, or as us cloners call it “The Duke,” doesn’t come with a gas tank, air filter, low oil sensor or exhaust system. The Duke also weighs in at 27.8lbs.

After the makeover and a 30 minute break in and cool down, the Duke was ready for its face off with Dr. Dyno. A 275 degree head temperature was achieved and like the Greyhound and Dupor remained within 25 degrees throughout the run. The Ducor made 9.18 horsepower at 3800 rpms with maximum torque of slightly over 13 ft. lbs. at 2800 rpms. Like the Greyhound and Dupor, the air/fuel ratio remained steady in the beginning but richened up after 2100 rpms and fell below 15 into the 14 range as maximum horsepower was achieved. Unlike the Greyhound and Dupor’s Ruiing carb the Ducor’s Huayi carb actually richened even further to 13 as power dropped off.

In summary, the Ducor seems to have an advantage with the Huayi carb. The extra torque and horsepower came in early and stayed ahead of the Greyhound and Dupor throughout the entire run as did the richer fuel mixture.

In conclusion, the blue Greyhound, yellow Dupor and yellow Ducor all ran without failure well past their manufactured suggested limits. Ungoverned and with better breathing, all surpassed manufactures stated horsepower and torque ratings. The Ducor’s extra power appeared to be attributed to the richer settings of the Huayi carb compared to the Huiing of the Greyhound and Dupor.

It’s easy to see why so many racers have started using clones to satisfy their racing sweet tooth. With some very inexpensive modifications to improve breathing today’s clones can achieve 9 to 10 reliable horsepower with gobs of torque which is a perfect combination for

short track racing. I highly recommend adding a certified billet flywheel for safety, and it would appear that most organizations are heading in this direction. Whether you’re a newbie to kart racing, on a budget or just want to have some family fun. Today clones may be just what you’re looking for.

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