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FUN TIMES

HEAVY-DUTY MACHINES — Fun Kart Series Part 4
By Paul Dilger – Courtesy of OPE Magazine

As we continue with our series on the fun kart industry, this month I am featuring the Manco XTK-710E heavy-duty fun kart.

Manco products, Inc. began operations in 1967 and is located in Fort Wayne, Indiana. Originally owned by Bill Hatlam, Manco first manufactured mini-bikes. Fun kart production began in 1968, and Manco has since grown to the largest manufacturer of fun karts in the world. Kent Rice is the current president and CEO and Tom Delong is vice president of sales. Manco PowerSports is now owned by a local investment company, having been sold in December, 2002. Manco also achieved ISO 9001 certification in 2002. Operating today in a modern 200,000-square foot facility with approximately 125 employees, Manco PowerSports can manufacturer more than 300 units per day on three assembly lines.

Besides manufacturing fun karts and mini-bikes, Manco PowerSports also imports a line of ATVs and scooters to broaden its product line. Manco takes great pride in its design and manufacturing quality. Many innovative accessories and safety features are a hallmark of its products. One of Manco’s most recent and significant changes has been the addition of the Robin/Subaru engine to all of its fun karts and mini-bikes. Manco has an exclusive relationship with Robin America, which gives it an advantage of a commercial-grade engine with a three-year warranty.

Like Brister’s Design and Manufacturing and Carter Brothers Manufacturing, Manco also has a wide variety of fun kart models for all ages, applications and terrain conditions. The basic entry-level kart I featured in the *August column here came without optional accessories. In the **September column on e-KMI, I looked at a high-performance kart that included the following features: an electrical system with lights and a starting system, a three-point retractable seat belt, a brush guard, a larger air cleaner, a manual carburetor choke, grease fittings on the steering knuckles, a solid positive-traction rear axle and a torque converter transmission. It also came with larger ATV-type tires, front wheel camber to enhance steering, adjustable heavy-duty shocks, a 9-HP engine, and a full front and rear suspension system. What else could you need on a fun kart? Let’s look at some of the features Manco uses to attract customers.

The Manco XTK-710E is not a lightweight machine. It has the heaviest-built frame and dry weight of all three machines I tested. The extended wheel-base provides a smoother ride than the smaller karts. The XTK-710E has a large driver and passenger compartment. Side panels along the leg area kept 90% of all the dirt, mud and water out of my face while making high-speed turns. With the addition of the optional rear fender, the kart stays relatively clean inside the operator’s compartment. The strong tubular design gives plenty of strength to make this a hard-working kart.

The kart arrived in perfect condition in a wood crate with the brush guard unassembled. This reduces the shipping costs to the customer. None of the karts I evaluated came with the brush guards assembled.

After removing the kart from the crate, my grandson and master mechanic, Dean, quickly assembled the brush guard while I set-up the battery. The kart comes with dirt or mud guard under the rear of the kart. This bonus shield keeps the bearings, brake, chain and torque converter as clean as possible, thereby extending their service life. This is an excellent feature since the torque converter cannot be disassembled and cleaned internally.

The XTK-710E has swinging arm suspension both front and rear giving the kart high ground clearance in the center of the kart. Just like Carter Brothers, Manco sets the camber on the front wheels with 1/8 t 3/8-inch toe-in to enhance steering at high speeds on dirt roads. This heavy machine, with a curb weight of 447 pounds, will reach 34-MPH and remains reasonably stable over rough, undulating terrain. Its overall length is 93.5 inches. The full suspension makes for a comfortable ride.

The grease fittings on the kart are a valuable feature. So far, we have seen that some karts don’t have any grease fitting. Some have fittings on the steering system and others, like the XTK-710E, have the grease fittings on the spindles and wheel bearings. This feature acts as a kind of insurance. If properly lubricated with molybdenum (aka “moly”) grease, the bearings will probably never need to be replaced. In addition, moly grease will have less rolling friction and won’t cake up like the grease in most sealed bearings.

If you look at the rear axle components, you may first notice the dust and mud shield below the axle. Considering the fact that dirt and mud are the greatest enemies of any mechanical part, this shield, which is standard equipment, will prolong the life of all the components. You would also notice that this machine has three pillow-block bearings. One bearing is located at each wheel and one in the center of the axle. This keeps the axle from flexing against the strong pull of the chain on the axle sprocket. The disc for the disc brakes is located between the axle sprocket and the left wheel bearing. The large-diameter disc increases the mechanical braking advantage over a small-diameter disc, thus increasing the kart’s braking power. Disc brake shoes also retain their braking capacity longer because they have less tendency to “heat-gloss” and lose some of their surface friction. Between and above the brake disc and the axle sprocket is the driven sprocket of the torque converter.

A torque converter ha no gears and provides a variable engine-to-axle speed as the pitch on the pulleys change. When a small engine pulley drives a large axle pulley, a “gear-type” speed reduction occurs. With a torque converter system, as the engine pulley’s pitch gets smaller (where the effective pulley diameter is larger) and the axle pulley’s pitch gets larger (where the effective pulley diameter gets smaller), the “drive/driven” ratio decreases. Karts are designed so that torque conversion only occurs at the engine’s lower RPM range until the converter locks up and the “drive/driven” ratio remains constant at higher speeds.

The torque converter transmission is comprised of two variable-speed pulleys driven by a v-belt. The drive pulley (attached to the engine crankshaft) starts off small to deliver maximum engine torque to the rear axle. As the engine speeds up, the drive pulley increases in diameter and the driven pulley (attached to a jackshaft assembly) decreases in diameter to produce maximum speed with less torque. I will explain later how this works.

Another standard feature on the XTK-710E is a cooling fan on the end of the drive pulley shaft. Heat transmitted from the engine drive shaft to the drive pulley Can be damaging to the rubber v-belt and shorten its life due to heat-cracking and glossing of the friction surfaces. This is a good feature to have on karts purchased for hard work and long travel times.

Most v-belt pulley drive systems have either a constant tension on the belt or the pulley is shifted in and out of belt tension manually. The kart torque converter system keeps the belt at constant tension except at idle. At idle, the drive pulley is at maximum separation, or width, and the belt rides on the bottom of the pulley shaft, where two brass rings that spin freely on the shaft. As the engine RPM increases, internal roller weights roll up ramps and away from the center in a radical direction inside the pulley cover and push the right side of the pulley toward the left side. This effectively pushes the sides of the pulley closer together until the belt is compressed and engaged. Upon engagement, the driven pulley starts to rotate and drives the kart forward.

To understand the driven pulley, we need to look at its three major components: the left face place, the right face plate and torsion spring.

1. The outside of the left face plate of the driven pulley is riveted to a plate that is welded to the left end of the shaft. The right end of the shaft is then keyed to the fixed cam, thus forming one rigid component with the left face plate.
2. The right face plate of the pulley is free to rotate about 60 degrees on the shaft relative to the left face plate as a load is applied to the pulley. There are two bosses with rubber tips that are riveted to the right face plate of the pulley. The rubber tips slide up and down the ramp of the fixed cam, preventing metal-to-metal gouging.
3. The torsion spring—not a compression spring—controls the rotational position of the right face plate pf the pulley with respect to the left face plate. In other words, the spring does not push the right plate toward the left plate to squeeze the drive belt, but rotates the right plate of the pulley back to its idle position when engine RPM decreases.

Essentially, as the belt moves the right face plate of the pulley out of index with the left face plate, the spring gets wrapped tighter (actually stretched) around the shaft. As the spring is wound around the shaft, it compresses in length and the right face plate of the pulley is pulled to the right. The v-groove between the two face plates of the pulley gets larger, causing the belt to run deeper in the groove as engine RPM increases. At higher RPM, the bosses riveted to the right face plate rotate into the valleys of the fixed cam, increasing torsional tension as the spring twists. As engine RPM decreases, the spring’s torsional tension rotates the points of the cam back to idle position when the spring returns to its original length.

Another standard feature on the XTK-710E is the parking brake. You simply press on the brake pedal and pull back on the parking brake handle. This brake holds even on steep inclines. This is a must-see safety feature!

The Robin 10-HP engine comes standard on the XTK-710E. Manco recently introduced the XTK-713E model, which is identical to the XTK-710E with the exception of its 13.5-HP engine. The extra horsepower will make this big machine very competitive in cross-country driving. All the Robin engines used in the Manco karts have a three-year warranty.

The XTK-710E has an extra-large gas tank for taking long rides. Inserted in the filler port of the gas tank is a (special) device. First, it acts as a strainer to filter out any particulate debris that would interfere with the engine’s carburetion. Second, the filter forms an anti-splash device that inhibits gas from splashing up into the gas cap on rough terrain. I don’t have any data on how long the engine will run on a tank of gas because I haven’t run the kart for more than two hours at a time and I like to keep the tank full!

The electrical system on the Manco kart consists of a starting circuit, charging circuit, ignition circuit, lighting circuit, battery and two safety key switches. The electrical components are located behind the operator’s seat, where they have good protection against brush damage.

The emergency or safety switch is located on the steering wheel. The operator can easily kill the engine with a thumb while keeping both hands on the steering wheel for maximum control.

I would like to express my sincere thanks to Jeff Platzer of Manco PowerSports for his time and expense in providing me with the materials for this article. You can contact Manco PowerSports at 4404 Engle Ridge Drive, Fort Wayne, Indiana 46804. The phone number is 800-643-7332. The company’s website is www.mancopowersorts.com.

This wraps up our series on fun karts. It was never my intension to do a kart-by-kart comparison because the variety of karts available to the consumer offers a wide array of choices. All the manufacturers have safety as their primary concern, and none of the karts I tested lacked in quality of design or manufacturing. I am convinced there is a kart to meet the needs of all interested consumers based on their age, budget and intended use.

ABOUT THE AUTHOR: Paul Dilger is a retired professor of agricultural engineering at Cal-Poly State University in California. He worked as a mechanic in the U.S. Army before attending college. After graduating from college, Dilger taught mechanics for 25 years. He is currently a private consultant helping companies develop quality service training programs. Visit Paul Dilger’s website at www.imslo.com.

Article is © July 2003 by Outdoor Power Equipment (OPE) magazine and used here with permission. OPE magazine is published monthly by Adams Business Media at 833 W. Jackson Blvd., 7th Floor, Chicago, IL 60607. For subscription information and requests, call Subscription Services at 847-647-7399.

* May issue of OPE magazine
** June issue of OPE magazine

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