It's just like fixing a bicycle flat tire, but MUCH BIGGER.
For instance - contrast these "tire irons" with the little plastic things you use to pry the tire off a bike rim.
Some newer/larger motorcycles don't have innertubes. Fixing one of those is more like fixing a flat in a tubeless automobile tire. Just keep in mind you CAN put an innertube in any tire, even a "tubeless" one.
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Step 1: Motorcycle Stand From Milk Crate
We're going to remove the front wheel.
I made a hasty motorcycle stand from a milk crate. I put a slab of 2x6 on top of that to spread the load. I propped the engine up on that. Fortunately there's a flat spot on the bottom of the skid pan that makes this arrangement very stable. Don't store your bike this way though, the milk crate plastic will sag and eventually your bike will fall over.
A double kickstand would hold the bike up just fine with the front wheel off, but this bike doesn't have one. This is my 1987 Honda TLR200 trials bike. It was stripped for racing, I'm in the process of putting improvised street legal signals and lights on it. That's why the lights on this bike look a bit odd. Expect to see that project soon.
Step 2: Wheel Removal - Don't Lose the Little Parts
Taking a wheel off is slightly different for every bike.
Usually you need to disconnect the brake cable and speedometer cable.
Usually there's an axle bolt. Sometimes there are other bolts clamping the axle bolt in place.
Sometimes when you remove the axle bolt there are little bushings like this that can fall out of the wheel. Don't lose these parts. They are very important.
Step 3: Tire Irons
You'll need three "tire irons" to pry your tire off the rim. One of mine is an official tire iron on the end of an old lug wrench. The other two are stainless steel bars that came off the broken mast of the free yacht. Make sure the ends don't have sharp corners or edges. You don't want to poke holes in your inner tube while putting it back in. That would make the job into something from Greek legend hell!
Step 4: Pry the Tire With the First Iron
Push the tire down away from the rim all the way around. That unseats the tire's "bead". That makes it loose enough to pry it up and over at one end.
Take the first tire iron and pry the tire over the rim. If it's hard to do this, push the tire down on the other side to keep it from springing up and reseating on the rim.
Make sure you don't pinch the innertube between the tire iron and anything else. That would puncture it.
Step 5: Second and Third Irons
Repeat with your other two tire irons. You might want to put your knee on the first one to keep it from getting levered up and hitting you in the face. If that happens you've got other problems as well. Most likely the tire has re-seated itself on the rim and isn't loose enough. Push it down away from the rim all the way around and things should get easier.
This tire is pretty badly cracked from SUV pollution in the air. It was stored in the shade but wasn't covered. It cracked badly anyway. I'll need to replace it soon so I'm not being careful with it.
If you care about your tire you can lubricate the edges with soap like they do at a tire shop before prying it on or off. If you ask a mechanic at a tire shop for some of that grease-looking rim soap they'll be happy to give you some. They'll be glad that someone knows about it and interpret that as a sign of respect for their profession.
What was I saying about SUV pollution?
Pollution from cars turns into nitric acid and other crap in the air. (NO2 + UV + fog -> SMOG)
It dissolves and erodes marble sculptures, makes acid rain that kills fish in lakes in Canada, and makes a lot of stuff deteriorate faster than you'd expect. Why is there so much of it?
While Karl Rove and his little playmates had America hypnotized, congress voted in some really bad laws. Sport Utility Vehicles (SUV) which are giant station wagons, were classified as "trucks" because they weighed so much. "Trucks" were exempted from emissions controls. A tax break allowed people to "expense" the purchase of a "truck" on their taxes rather than "depreciating" it. That means anyone with business income could take money they'd ordinarily use to pay taxes and buy giant cars (SUVs) with it instead. General Motors made a fortune selling these tax-subsidized over-polluting gas-guzzlers. The situation was even worse than it seemed at the time. Our tailpipe emissions standards are measured in "parts per million". These huge engines pump out a whole lot more parts and millions. Children living near freeways developed athsma and other medical problems more than they would have in France or other more frugal countries. We invaded Iraq, which happens to have a lot of oil. When the crash came, GM was making gas-guzzlers that no one wanted. GM failed. We tax payers now own GM. And a lot of SUVs that no one wants. When we get "cash for clunkers" from the government we buy small foreign cars. Does anyone remember the 1970s? If you'd like to know what it was like, look around.
Step 6: Pull
Now you should be able to pull the bead of the tire over the rest of the rim by hand.
Step 7: Pull Out the Tube
Usually there's a little nut on the metal valve stem. Remove the nut. Push the valve into the rim. Reach in and pull the whole innertube out.
Look and feel around inside the tire to find what caused the leak. Nails and staples are pretty common. Sometimes the head wears off from driving so it's really hard to spot from the outside.
You need to find it and pull it out or you'll get another flat right away.
Step 8: Inflate and Bubble Test
Put some air in the innertube to puff it up.
Fill a tub with water. Push the tube underwater and look for bubbles.
Once you find the leak, go look and feel around inside the tire until you find the nai/thorn/bullet hole or whatever caused it. Don't forget to fix the cause of the leak so you don't just get another leak.
These leaking bubbles are coming from around the valve stem. That's trouble. I don't have any patches with a built in valve. They exist but the nearby auto parts store doesn't carry them.
I think I remember what caused this leak originally. Various friends were riding this motorcycle to learn how to ride. They didn't notice that the rear tire was low on air. Jerking around with the clutch made the loose tire spin on the rim. The tube stretched and ripped a little here at the stem.
Alex, Alison and I cobbled a patch around the stem by cutting a hole in the middle of the patch. That held for a couple of years, but the stem rusted a little and that opened the leak again.
Step 9: Maybe Slime?
Sometimes when I cut an innertube up for lashings a lot of slimy stuff comes gushing out.
That's a product called "slime" that's supposed to fix flat tires. Or competing products with equally revealing names.
I considered getting some to try to fix this one. Then I realized there was something slimy inside this tube already. Sure enough, it already had slime inside it but it leaked anyway.
Step 10: List of Other Repair Alternatives
If the leak hadn't been right by the valve, I could have patched it with a regular bicycle tire patch.
That process is exactly the same as patching a bicycle innertube.
A replacement 21" motorcycle innertube costs between $8 and $15 online. That would be the best option for this tire. Probably retail price is similar. Unfortunately there's no motorcycle parts store nearby.
A pack of innertube patches with a built-in valve is $10 for 4 patches on Ebay.
Might be a good thing to have handy, but by the time I needed it again it probably wouldn't be handy any more.
I considered cutting a patch and valve from a bicycle innertube and gluing that on. But the slime inside this tube would have made it hard to glue that on properly.
Then I remembered my parts bike. It has the same size front wheel, and it even holds air!
I deflated the tire and pried the tire off the rim. I pulled the tube out without removing the wheel first.
Obviously I'm not thinking clearly. I could have patched the tube without removing the wheel, but I have to remove the wheel to get this tube off the fork.
Step 11: Install the New Tube
I leave a little air in the tube so it won't collapse. That helps keep inside the tire so I don't puncture it with the tire irons.
I put the valve through the hole in the rim and install the little nut on the valve so it doesn't pull back into the rim.
Step 12: Pry the Tire Back Onto the Rim
I use a tire iron to pry the tire back onto the rim. Once again I push the tire down on the other side so it's loose enough to do this.
Watch for the dot!
New tires usually have a dot on the sidewall indicating the heavy end of the tire. Put this dot away from the valve stem. That will make the wheel more balanced.
This tire also has an arrow indicating the direction it should rotate. We never took this tire all the way off the rim, so the arrow still points the right direction.
Step 13: Testing!
Inflate the tire, let the air out again, and inflate it again. This is a trick I learned from my brother Mark. It makes the tube and tire shift around and get evenly seated around the rim.
Then you can let it sit around for a while to see if it holds air.
If you're in a hurry to know for sure, put it in the dunk tank.
Alison Murphy tests a tire in 2007 by dunking it in the waterjet cutter. As soon as we did this I regretted it because of abrasives in the tank, but it caused no apparent harm to the brakes or hub.
Put the wheel back on the bike and go for a ride!