How to Fix 8 Common Issues on Older Bikes

Last Update: January 2021

Riding an old bike has its charms, regardless of whether you bought an old one or you’re riding the same since it was new.

Both Honda and Harley Davidson, and everything in between, go through similar problems and mechanical issues over time. These are quite common problems that owners of old bikes have to deal with.

Luckily, most of these problems are solvable with just some basic knowledge and a few tools. Take a moment to read the article below as we explain how to fix 8 common issues on older bikes with ease.

A Definition of an "OLD" Motorcycle

Classic Motorbike

This isn’t an official term, and it can tell about more than just the age of your motorcycle. More often than not, it can be used to describe a brand new motorcycle that just has “the look” and simplicity of an older motorcycle.

When it comes to age, most people consider all motorcycles over the age of 25 to be classic. However, the term indicates more than just its age, so it might often refer to design and appearance as well.

Vintage Motorbike

This is an official term, and it’s a bit more precise than the one we described above. The American Historic Racing Motorcycle Association has two different designations for vintage, describing the type of racing the particular motorcycle is meant to do.

Motorcycles for motocross racing are considered vintage if they were built before 1975, while those meant for road racing are vintage if they were built after 1975.

Still, some people use the term to describe the looks and design of relatively newer bikes as well.

Antique Motorbike

A motorcycle is considered to be antique if it’s 35 years or older, according to the Antique Motorcycle Club of America. It’s the official designation used in the U.S.A., although the definition isn’t always as clear.

Some states allow you to register or license your bike as antique even if it’s just 20 years old. For example, if the vehicle is only owned as a collectors’ item for car shows, club activities, or parades, it can probably be registered as antique even if it’s not older than 35 years.

Common Issues Encountered with Older Bikes & How to Fix It

Rust in the Fuel Tank

Rust is a common issue with old bikes, and it can appear pretty much anywhere on the vehicle. Still, the most common place is the inside of the gas tank.

It happens due to various reasons combined over an extended period. Although it is big of a deal, it sounds scarier than it really is. Plus, there are simple ways of preventing it from happening again once you fix it the first time.

How it Occurred in the Gas Tank

Rust can appear in your metal gas tank if you don’t keep it full of fuel all the time. If you often park or store your motorcycle for an extended period with some fuel in the tank, it’s inevitably going to cause rust.

What happens is that the water causes condensation within the tank, causing the metal to oxidize. This might not happen the first time you store your bike, or it might not happen at all. However, it’s likely to happen in high humidity locations more often than in dry areas.

Ways to Remove Surface Rust

There are several ways to remove surface rust, depending on the tank and filters you have. Wet sanding is the old method that’s pretty simple.

Begin by removing and draining the tank, while also removing the plumbing such as fuel selector valve and fuel sender. Add 16 ounces of distilled water combined with about the same amount of fine gravel or pure sand. Shake it a bit to sand out the surface rust.

Make sure to rinse and repeat the procedure of shaking and rinsing as needed. If that’s not doing much for you, try using BB’s, quartz, or another higher-abrasive material. Use a garden hose to rinse before rinsing with distilled water and gasoline.

It’s a good method to use if you have flaking rust. It’s going to help you remove the flaking, exposing the metal before you proceed with any other method.

Inspect the interior of the tank for rust remains. If there’s none left, you should replace the filter after maybe 5 to 7 days of riding. It’s to ensure that the filter is clean because there might be some sand residue if you didn’t rinse as well.

There’s a new way of doing it, by using the Yamaha’s Fuel Tank Rust Remover. It’s a two-part kit of chemicals that are a bit more efficient than the method we described above. However, it takes some precision and awareness since you’d be working with chemicals.

How to Prevent Rust in Gas Tanks?

The best way of preventing rust in a gas tank is by filling it to the maximum. It’s especially important to do if your bike will sit in one place for more than a day or two. If it’s going to be stored for weeks, you should consider using a fuel stabilizer.

If you’re storing it for more than three months (see best storage sheds), make sure to drain a half-cup of fuel from the bottom of the tank. Top it with new fuel every three months so that it’s always fresh.

Vacuum Leaks

This is another quite common issue that occurs with an old motorcycle. It’s somewhat easy to figure out, depending on your experience.

What is a Vacuum Leak?

A vacuum leak happens when extra air goes into the fuel/air mixture produced by the carburetors. It leans out the mixture, causing poor running conditions.

This is one of the most common issues in older motorcycles, but it’s luckily somewhat easy to fix.

What are the Common Areas of Vacuum Leaks

The carb holder, or rubber boots, is the most common area of vacuum leaks. The rubber dries out over time, degrading and cracking. The boots become brittle, although they might look fine before you stretch or bend them.

Another area where this might occur is at the throttle shaft seals. The leaking is usually caused by a worn throttle shaft, bad seal, or both. These are the most difficult to replace as some carbs need tight clearance between the body and throttle shaft in order to minimize air leaks.

You might also experience vacuum leaks in the fuel pump diaphragm and the tubing, which leads to intake.

Symptoms

Symptoms of vacuum leaks are many and often misinterpreted as something else. Figuring this out requires some experience, unless a few symptoms occur at the time, making it easier to pinpoint what the issue is.

Some of these symptoms might be confusing. Riders often mistake vacuum leaks for out-of-synch carbs, so make sure to confirm what the issue is.

For this reason, it’s best to consult a professional mechanic if you aren’t as sure about these symptoms. Sometimes, they can be a bit confusing to people who don’t have as much experience.

Diagnosis

Although the symptoms are easy to confuse with a few other issues, diagnosing leaks is relatively simple. It’s that much easier to do when the leak is large and affects your performance.

All you need to do is spray one of the few products in the suspected area. You can use starting fluid for this, but make sure to wipe it off immediately as it can remove paint. If that sounds too dangerous, you can use propane, water, or WD-40.

Spray one of these in the area where your engine is idling. If you notice any change in idle RPM, you have a leak.

As you see, diagnosing a vacuum leak isn’t as tricky. Still, you might struggle a bit if you lack the experience or if you’re a new rider. For this reason, you might want to consider taking your motorcycle to a professional mechanic.

Carburetor Problems

Carburetor problems happen with nearly every old bike. It’s one of the most common issues that occur due to many different reasons. However, you must address the issue as quickly as possible because it can greatly affect your safety on the road.

What is a Motorcycle Carburetor?

Carburetors are complicated devices, designed to mix gasoline and air so that the engine can run smoothly. Mixing the two isn’t as simple as it may sound, so it’s quite normal for an older bike to develop issues with the carburetor.

Most motorcycles in America have side-draft carburetors that mount horizontally to the engine. In Europe, things aren’t much more different, so the issue can usually be tackled the same way.

(Need to clean your carburetor? See our round-up of carb cleaners.)

What are the Types of Carburetor?

There are two types of carburetors that work in different ways.

Although the two types differ in terms of simplicity, they provide the same thing, and they’re essential for your motorcycle.

What Causes Carburetor Problems?

Carburetors wear over the years, much like all mechanical devices. These require regular maintenance and adjustment in order to work properly.

The two biggest problems are running too rich or too lean. A mixture that’s too lean will give you an erratic idle, stalling when not fully warm. A mixture that’s too rich will give you a rhythmic misfire and black smoke in the exhaust.

Lean mixture means that the carburetor is delivering too much air, while too much fuel means that the mixture is too rich.

Fork Oil Leaks

Does the Front Shock Absorber and Piston Spring Need Oil?

Forks are much more complicated than most people think. Forks usually aren’t powerful enough to handle the entire front end load of the motorcycle, which is why they’re filled with a viscous liquid called fork oil.

It has to be the right kind of oil as well, which is another thing to remember. The liquid that’s not viscous enough, like water, won’t provide enough lubrication. It causes friction and possibly even damage.

How to Maintain Fork Oils

Forks are the main things that keep you from feeling every single bump on the road. Although they do massive work, riders often forget to maintain them properly and regularly.

Luckily, maintenance is pretty simple. Every front fork has a closed chamber where oil is kept. This allows the oils to keep their viscosity for a longer period.

You can check the front shock absorbers whenever you service your motorcycle. If you notice the motorcycle getting rough or making squeaking noises, it might be time to change the oil. You should do this every year or two, depending on how often you ride.

How to Change Fork Oils

Fork assembly is somewhat complicated, which is why it’s always better to leave oil changes to a professional. If you still want to do it yourself, you should first remove the entire assembly off.

Change the oil of one fork at a time and try not the get the piston of the fork out. Check if your fork has an oil draining outlet. If it doesn’t, you have to open the piston and spring setup to get the oil out.

Put only the recommended amount of oil. Once you change it, pump the forks up until the air bubbles are no longer showing.

Check Fork Oil Grades

Oils are graded according to their load-carrying capacity and viscosity. Because the load varies from bike to bike, you’ll notice that the manufacturers use different grades.

Fork oils have their SAE grading ranging in the multiples of 5. The highest numbers indicate better loading capacity.

Old Tires

Tires tend to be a bit confusing because most people struggle to understand how old is too old and when should they get a new pair. Read more on how long tires last.

The technology has advanced quite a lot, so tires are now tougher and more durable. Still, it’s critical for you to know when you should finally replace them.

The entire issue gets even more confusing if you have old tires that still have enough of tread life. Replacing these depends on many things like how they were stored and how willing you are to risk using them.

Most riders overlook tires, especially on those motorbikes that have low rear fenders. In most cases, people don’t check their tires often enough.

Even if the tires look like they have enough life left, they can still fail you at critical points. This happens because the rubber ages and loses its effectiveness before most of us get to wear the tires down.

Luckily, most manufacturers rarely sell tires that are older than five years. For this reason, you’re better off buying from the manufacturer.

There’s a date code stamped near the DOT stamp. It’s a four-digit code that indicates the week and year of when the tire is made.

If you need to purchase new tires, check our guide.

Check the tires at every oil change. Here are a few things you should inspect:

Motorcycle Oil Leak

Fixing a motorcycle leak doesn’t require any special skills and tools. You can do it on your own, but it’s important that you act fast. Identify where the leak is and proceed to fix it.

Why Is There an Oil Leak?

Motorbikes are relatively simple, but engine oil leaks are always quite scary to everyone. Leaks are mysterious and can indicate multiple issues. However, they’re also quite common and can happen with newer motorbikes as well.

There are two main reasons why your motorbike is leaking oil. The first is probably faulty gaskets found on the valve cover, crankcase, oil pan, or the cylinder head of the engine.

Faulty plugs are another reason why there’s an oil leak. Oil drain plug, valve cover plugs, and crankcase side plugs are common places for oil to leak.

Most often than not, it’s the fault gaskets on the engine. The four most common gaskets to leak are the valve cover gasket, oil pan gasket, crankcase gasket, and cylinder head gasket. These have the highest internal pressure, which causes the oil to push between the meeting surfaces if the gasket isn’t doing its job well.

Gaskets crack and shrink over time, and they become less effective. There’s constant pressure, so it’s quite normal for them to fail at some point.

As we said, the second reason is because of faulty oil plugs. In most cases, it’s the oil drain plug that causes leakage because it’s the easiest one to damage.

Oil plugs might also leak when they aren’t tight enough. Your motorbike vibrates, which causes the plugs to lose after a while. For this reason, it’s important to ensure that they’re tight at all times.

Identifying the Cause and Simple Fixes

Keep in mind that most leaks can be fixed with a bit of effort and some basic tools. Oil drain plugs are relatively simple to fix. All you’ll need is the replacement drain plug and some fifteen minutes.

You can also fix most of the gaskets we mentioned. Valve cover gaskets may require you to remove the gas tank and a few bolts, but that’s also quite simple.

The oil pan and crankcase gaskets are equally as simple to work with. However, make sure to check your owner’s manual for instructions on how to do it properly, depending on the bike you have.

One thing that we don’t recommend that you do by yourself is fixing the cylinder head gasket. It requires you to take the top part of your engine apart, exposing vital parts. It’s something you shouldn’t be doing if you’re inexperienced because a little error could damage your engine.

Additional Tips

One of the most important things to remember is never to work when the engine is still warm. Make sure to allow it to cool. Also, keep in mind that some leaks cannot be fixed without replacing the defective part.

You might want to consider getting a leak detection kit if it’s your first time dealing with something like this.

Electrical Wires

Electrical systems are usually scary for most people, even those who have some experience in motorcycle mechanics. Luckily, old bikes don’t have such complicated systems that you can now find on newer models.

Identifying the Source and How to Resolve the Issue

Most people take their bikes to a mechanic without trying to fix the electrical problem. Finding and identifying the issue isn’t as difficult as long as you know what the function of each component is. The trickiest part is usually trying to figure out where to begin the process.

Most electrical components join together in harness connections. This is one of the most common places where issues can occur. Pin-out connectors, male/female blade connectors, and male/female bullet connectors develop different problems over time.

Check the connection between two wires. You either have a broken wire that’s melted or rusted or a wire that’s pinched under the seat or gas tank. In many cases, the cable is just disconnected.

If not, you may have bad grounds. This issue is the trickiest to find because there are many different loads that share the same ground. As a result, the system can play you by failing to function, giving false alarms, or even catching on fire.

Faulty grounds are a common problem. Checking all the grounds shouldn’t be as complicated if you know where they all are. If not, you’ll have to consult with the service manual for the locations.

Luckily, fixing this issue usually only requires patience. It’s not expensive to fix this, but make sure to check for faulty grounds as soon as you start troubleshooting.

If you’re not dealing with faulty grounds, you should check the battery cables. Loose battery terminals are probably the most overlooked issue that people forget to check.

You should check these cables early in your troubleshooting process to avoid looking for an issue when you should only tighten a battery cable. Loose cables will cause a problem sooner than later, so make sure to check them from time to time.

Another thing you should check is if your main fuse. A faulty or blown fuse can cause plenty of issues, causing your motorbike to run poorly or die at random times.

This is quite frustrating, and it might make it seem like there’s something else wrong with the vehicle. It usually becomes faulty due to excessive vibration or age, which is why you should keep a spare one at hand at all times.

If it continues to blow even after you’ve replaced it, you should check other electrical components that cause excessive amperage.

Motorbike Brakes

We can all agree that the brakes are among the most critical components of your motorbike. They’re necessary for your safety and that of other people in the traffic.

For this reason, faulty brakes are not to mess with. You should take the matter seriously, fixing whatever the issue is as soon as possible.

What's Causes Brake Problems & How to Fix It

One of the most common issues is brake overheating and binding. Binding occurs when liner binds to the brake drum, staying that way without pressing the lever. It usually happens to do to overheating, but other things can trigger the issue just as well.

Defective springs can cause overheating and binding, and replacing them is the only way of fixing the issue.

Another problem is the loss of brake fluid. Keep in mind that an insufficient level of oil can decrease the efficiency of your brakes, which is why you should be careful when fixing this issue.

Make sure to check the level of brake liquid regularly. You might also deal with leakage due to a hole somewhere in the system. Check the reservoir and the caliper as well as every joint in the system.

The air in your braking system can also cause trouble. The brakes might work, but their efficiency will be reduced, which is why it’s important not to overlook the issue.

Air can only get in if there’s a hole in the system, and you have a leakage. As the oil leaks out, the air gets in, causing all the trouble.

Although most of these problems seem quite simple to fix, we recommend you have a professional check this for you. Tampering with brakes is dangerous, and there’s a massive risk of tragic accidents.

Conclusion

As we said, older bikes have a unique charm about their looks as well as performance. However, they’re usually also more prone to breaking down due to several reasons.

The best way of avoiding this is by prevention. In most cases, you can prevent many of these issues from occurring with simple and regular maintenance.

Because older motorbikes are more prone to developing certain problems, they also require more detailed maintenance and care.

Hopefully, our guide can help you fix some of the common issues older bikes deal with. However, keep in mind that your safety should always come first. For this reason, have a professional mechanic help you out if you don’t have as much experience.