Installation Tech Tips:

1. Always make sure all the pieces of the old clutch are removed from the crankshaft before attempting to install a new clutch. It is not uncommon to think all of the old clutch has been removed when it hasn't.

2. All centrifugal clutches must be retained on the engine crankshaft with a flat washer & bolt in the end of the engine crankshaft so that the clutch will not slide off, or you can use a retaining collar on a centrifugal clutch. Many crankshafts are already drilled and tapped. The crankshaft also has to be no shorter than 2-1/4" in length. A centrifugal clutch will not be properly supported on a crankshaft that is too short. See our installation instructions located [here].

3. Oil the bronze bushing or needle bearing on a centrifugal clutch at the crankshaft with a few drops of a 30-weight motor oil before each use. Never oil the clutch shoes or excessive slippage and wear will result. Regularly check for loosened mounting bolts and retighten. This is extremely important. Never reuse a bent or distorted snap ring on a centrifugal clutch.

4. Check the alignment of the sprockets. The clutch sprocket and the rear drive sprocket must be aligned to provide the best overall performance. (If they are not aligned, the chain can come off and cause damage or injury.)

5. Check the chain tension. The chain should have approx 1/2" of movement at roughly half of the distance between the front and rear sprockets. (If the chain is not tight it can come off and cause damage or injury. If the chain is to tight it can cause premature bushing and chain wear.)

Clutch Removal Tech Tips:

1. Remove the bolt with the correct size wrench. The clutch should then slide off of the crankshaft. A clutch that has been on a crankshaft for a long time will often be rusted to the crankshaft. Some light weight oil can be put on the crankshaft and allowed to spread between the clutch and the crankshaft. DO NOT PRY against the engine to try to remove the clutch because engine damage, as well as clutch damage may result. If you can't get the clutch off of the crankshaft, seek assistance from a small engine repair shop, or local dealer.

2. Always make sure all the pieces of the old clutch are removed from the crankshaft before attempting to install a new clutch. It is not uncommon to think all of the old clutch has been removed when it hasn't.

Maintenance Tech Tips:

  The centrifugal clutch whether it is being used in a minibike or a go-kart needs to be lubricated each day that you ride. To get best results oil the clutch before and after each time that you ride. YOU CAN NEVER OIL THE CLUTCH TOO MUCH. It is a good idea to oil the chain at the same time that you oil the clutch.

  The Hilliard Extreme Duty clutch contains an oil impregnated bronze bushing. 20% of the weight of the bushing is the oil that is impregnated into the bushing by the manufacturer. This oil can leak out, or can evaporate over time, and must be replaced. The bushing is a loose fit into the sprocket and is driven by the crankshaft. A snapring holds the bushing into the sprocket on all LD4S-“x”L series clutches. The LD4S-“x” series clutches DO NOT HAVE A SNAPRING.

  To oil the clutch bushing shut the engine off, apply standard organic motor oil (SAE 10w-30) to the snap ring area. DO NOT USE SYNTHETIC MOTOR OIL’S because the special additives in these oils prevent the required steel to steel contact between the clutch shoes and the clutch drum. Loosing this steel to steel contact will make the clutch slip, reducing its torque transmission to the ground. Be sure to oil the bushing on all sides. To ensure that the oil is evenly spread out over the bushing surface rotate the clutch housing (the part attached to the sprocket). Oiling the clutch while it is warm will allow the porous bushing to soak up more oil, and will help replenish the oil that was inside the bushing when it was new.

  Thoroughly cleaning the dirt from the clutch will help prolong its life. Dirt is abrasive and can act like sandpaper. The rough surface will prematurely wear the bushing, sprocket, chain, and other parts of your Kart. Cleaning all of these areas regularly will prolong both the clutches life, and that of the kart. Preventive maintenance is the secret to prolonging the life of the clutch.

  If you find that the drum and sprocket assembly wobbles on the engine shaft, this indicates that the bushing is wearing out. You should buy a replacement bushing before you cause damage to the sprocket or sleeve with steel to steel contact. A worn bushing can also lead to a thrown chain. Replacing the bushing early when you first see a wobble will prevent damage to the clutch.

  A visual inspection of the clutch will also let you know what may be going on with the clutch in your application. For example, a clutch with blued shoes will indicate that the clutch is slipping. If the clutch is slipping, a user may want to consider a gear reduction, or a different riding technique. Also changing the tire size will affect the overall gear ratio, if your clutch is slipping try a smaller diameter tire. (Read the riding Tech Tips). If the bushing is blue or purple, again heat is a problem however, the bushing needed to be oiled more often, and should be replaced. The blued bushing is also an indication that the clutch is slipping.

  If your go kart takes off by itself when the engine is started, with no one in the drivers seat, that is an indication that the clutch is badly in need of inspection. Turn the engine off and park the machine up against a tree or fence to prevent it from taking off when you crank the engine again. You can also put the rear end up on blocks so the rear wheels are not touching the ground. If the wheels do move when the engine is started, turn off the engine and try lubricating the clutch bushing. Give the lube enough time to penetrate the clutch then restart the engine. If the machine continues to take off by itself even after the clutch has been oiled, remove the clutch and perform a visual inspection of the bushing, and the springs that hold the shoes on. If the bushing is blue or purple in color, and or the springs are loose, then replace those parts as needed. If other parts are damaged then the clutch must be replaced.

Ordering Tech Tips:

1. Find out if you have a #35, #40, #41, #420 chain. To tell if your chain or your sprocket is #35, #40, #41 or #420 pitch, measure the distance from the top of one tooth of your sprocket to the top of the next tooth. Another way is to measure from the center of one pin on your chain to the next pin.

2. Find out if the number of teeth that you are using currently by counting them off of your current clutch. If you don’t know how many teeth you want contact a go kart dealer.

3. Measure the engine crankshaft to find out what size bore should be in the clutch. The bore is the hole in the middle of the clutch that fits over the engine crankshaft. To accurately measure the outside diameter of your engine crankshaft, use a crescent wrench as shown in the drawing. Tighten the wrench around the crankshaft and measure between the jaws of the wrench. This measurement is the outside diameter.

4. Verify that the engine’s idle speed is below the engaging speed of the clutch that you are looking to purchase. Standard engagement speed for this type of centrifugal clutch is 2200-2400 RPM. The engagement speed is the point at which the clutch will start to transmit torque to the wheels, or driven member. The engine’s idle speed should be no more than 2000 RPM for these clutches to work properly. A higher idle than 2000 could start the clutch to engage prematurely.

Riding Tech Tips:

1. Do not ride with an over tightened chain, do not ride with your foot on the brake, do not ride in soft sand, loose dirt, or try to climb hills. This will wear out the center bushing on a centrifugal clutch. Also, a centrifugal clutch should not be used with tires over 15" in diameter, and do not ride in soft sand, loose dirt, or try to climb hills with a centrifugal clutch.

2. Do not ride with a dry or dirty chain. Chains should only be lubricated with chain lube. The chain should have approx 1/2" of movement at roughly half of the distance between the front and rear sprockets.

3. Parallel, true alignment of all sprockets is important to prevent excessive wear and jumping of chain.

4. Never ride using the brake and gas pedal at the same time. Never both together. Make sure that the rider knows which pedal is the gas, and which is the brake, as they may not know, and may be using the wrong one. Riding in this fashion generates heat that will evaporate the oil in the bushing, leading to premature failure of the bushing. This style of riding is most often seen with children. Children step on the brake and gas pedal at the same time because they get nervous of the speed of the kart. Riding the brake keeps the speed down but it also forces the clutch to slip which will dry up the oil in the bushing. Riding in this manner will also put excessive wear on the brake.

5. Avoid stop and go driving. The longer the clutch is locked up, the easier it is on the clutch. Driving at full rpm (with the wheels moving) will cool the clutch down. The longer the kart is driven continuously, the longer the clutch life will be. Driving with the clutch locked up gives the clutch a chance to cool down.

6. Be careful when limiting the speed of the kart by adjusting the high speed limiter found on some engines, or by limiting the travel of the throttle. By limiting the speed of the engine the torque carrying capacity of the clutch is reduced drastically, causing the clutch to slip. The heat build up of the clutch while slipping will cause premature failure of the clutch bushing. The best way to slow the speed of the kart down is to provide a lower gear ratio. Some manufacturers provide a gear reduction kit to slow down the karts. The engine speed needs to be allowed to run up close to the engine manufacturers recommended top speed.

7. Watch the rider weight of the kart. Having riders that are to heavy will also allow the clutch to slip, leading to the same problems mentioned earlier. If the kart needs to be run with the heavier rider, try to acquire a gear reduction kit from the manufacturer if available. If it is not available, try contacting a dealer for recommended gear ratio.