Thursday, August 23, 2012

Tech Thursday

Going Tubing!
Unfortunately, this tech article isn’t going to talk about water or snow tubing. Yes, tubing is fun, but replacing a tire and tube on a motorcycle takes some patience. Unless a motorcycle comes with mag wheels, it is going to come with spokes. With spokes, it is almost impossible to run a tubeless tire. Spokes on rims create a problem of air seepage. The spoke is connected to the rim with a nut which is not air tight. Motorcycle manufacturers ran an inner tube inside the tire to solve this problem, however inner tube installation can be difficult.

Tube tires have been around for a very long time. Though the first automobiles and motorcycles may have had hard rubber tires, some of the earliest pneumatic tires were tube. Spoke rims have been around for nearly 100 years. This article won’t really get into changing a 100 year old inner tube. Motorcycle manufactures have spoke rims on many models, new and old. Whether it’s a Kawasaki, Honda or Harley-Davidson, changing an inner tube is pretty close to the same process.

First and foremost, changing the inner tube correctly is very important to the safety of the rider. Since there are only two wheels, if the tires are not properly inflated, it presents a huge hazard to riding a motorcycle. This tech article is only an aid to changing a motorcycle tire with a tube.

The first step is to remove the wheel from the motorcycle. Taking the front wheel off is usually a much easier task than the back wheel. Front wheels are held in a telescopic front end, usually by an axle and a brake-stay. Disconnecting each of these is usually as simple as removing a nut on the one side. A rear wheel which has the axel, brake and (chain, belt or driveshaft) holding it in place, can be more difficult. Please refer to the manufacturer’s service manual to remove the wheels.

Once the wheel is off, put it on a soft surface. Let the air out of the tire with a valve stem removal tool or small pliers. The tire may be stuck to the rim, so its bead will need to be broken loose. Pry the bead loose or use a special bead braking tool against the tire and rim, being careful not to scratch the rim. Use oil or soap to lube the bead and rim, and with 2 tire irons begin working the tire off the rim. Take small "bites" to work the bead off gradually. Once one side is off, it may be possible to remove the inner tube. Continue to use the tire irons and remove the other bead off the same side of the rim. Examine the rim to make sure it is not bent or has any sharp edges. In the center of the rim, there is a large rubber band that covers the spoke ends. If the rubber band is ripped or a spoke end is showing, replace the band.

To put the new tire on, reverse the process. Some tires have arrows pointing in the direction they should rotate. Work the one bead of the tire onto the lip of the rim. This may involve stepping on the tire to keep the one side in place and lubing the tire. The tube must be installed before the other bead of the tire is put on the rim. The valve stem will go through a hole in the rim and will be held in place with a nut. Put a little air in the tube to help it take shape. Lube the tire bead again and use the tire iron to work it under the wheel lip. With little "bites" again work the tire on. Be very careful NOT TO PINCH THE TUBE. If the tube is pinched and leaks, the whole process will need to be done again. Fill the tube up to its recommended pressure and make sure the bead seats fully. DO NOT OVER INFLATE THE TUBE, as it may burst or the tire may come off the rim.

Make sure the wheel and tire assembly are properly balanced, then they can be mounted back onto the bike. Most shops will only warrantee work if their tire and tube are used. A mismatch tire and tube usually leads to a void in the warrantee. Never patch a tube; always replace it, and make sure everything is DOT approved.

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