Problems With Yamaha TMAX, XMAX & SMAX – (6 Known Issues)

Yamaha’s range of maxi-scooters offers an attractive combination of innovative technology, practicality, and outstanding ride quality.

Like any vehicle, the maxi-scooters have puzzled and troubled a few of their owners over the years; sometimes it’s just a simple matter of taste, sometimes it’s a widespread issue.

Regardless, if you’re in the market for one of these quality peds, their stories might be able to save you some time and money.

Here are the most common problems associated with the Yamaha TMAX, SMAX, and XMAX:

Yamaha XMAX

The following are common problems reported by owners of the Yamaha XMAX:

1. Scooter Won’t Start

Let’s start with the problem we dread the most. A few XMAX owners have complained about problems with their bikes not starting.

A scooter that won’t start isn’t much of a scooter at all, and it’s a real bummer when this catches you off-guard while you’re on your way somewhere important.

This isn’t indicative of a single isolated issue; our research has pointed to a few different unrelated culprits, many of which tied to standard wear and tear, poor maintenance, or improper storage.

Let’s take a look at a few of the culprits for XMAX Scooters that wouldn’t start.

I. Battery Issues:

Always check the easiest thing first. If the battery’s bad, the scooter won’t start.

Some owners found it was as simple as loose battery terminals or that corrosion needed to be scrubbed off after the scooter had been sitting in a wet garage unkept for a year.

If the terminals are good, check the quality of the battery itself.

If the engine is turning over slowly or doesn’t turn over, the battery’s voltage is likely low. A good way to know if a bad battery is the cause of the problems is to do a multimeter test.

II. Bad Stator or Regulator/Rectifier

A few XMAX owners traced their starting problems back to scooters charging system,

The stator is the coil of wire inside the engine case. As the bike rides, the stator’s magnet rotates.

As engine speed accelerates, the stator outputs more and more power, and if left unregulated, it can overcharge the battery and kill it.

The rectifier/regulator is the component responsible for regulating that current. If your rectifier is bad, the battery will be damaged. If the stator is bad, your battery won’t charge while riding, meaning it’s outputting more power than it’s generating, and eventually, it’ll die.

If you’re riding your bike regularly and your battery won’t hold a charge, you’ve replaced the battery, and the new battery is having the same issue, inspecting the stator is the logical next step.

If you’re having issues with batteries overcharging and exploding, there’s a good chance the problem is the rectifier/regulator.

Checking that your battery is charging correctly and is in top condition is part of routine maintenance; a vehicle is only as good as its battery.

III. Worn or blown fuse:

Another cause responsible for the scooter-won’t-start effect is a simple blown fuse.

Fuses often wear out with age, meaning they may start to malfunction at some point.

If a fuse is blown, the spark plug won’t get the required spark to start the ignition process, and your moped isn’t going anywhere.

2. Warped Front Brake Discs

Disc brakes are widely considered the most efficient brake set-up these days, so it’s no wonder that Yamaha included them on the XMAX.

When you apply brakes on a scooter with disk brakes, like the XMAX, the brake caliper squeezes the brake pads onto a disk used to the wheel, and the friction on the disk helps your bike stop.

As you can imagine, worn-out or warped discs negatively affect braking performance on any 2-wheel vehicle.

If the brake discs on your bike are worn, you will see an increase in stopping times.

Some XMAX owners have reported cases of the brake discs on their motorcycles warping. If your brake discs are warped, your stopping power will decrease exponentially. 

Asides from reduced braking power, another sign of warped discs is vibration or squeaky noises while braking.

According to customer complaints, the front brake discs are the most susceptible to warping. Here are some things that could cause warping on the XMAX scooters:

I. Extreme Heat:

Under harsh braking, the brake discs will get unusually hot and expand.

This is often followed by an in-flow of cool air, which causes the discs to contract. As this expansion and contraction process is erratic, it often changes a brake disc’s surface.

Such changes often make the surface of the disc uneven, leading to warping.

II. Regular Wear-and-Tear:

Like other parts of the brake assembly, the brake discs wear out.

The wear can lead to the disc surface becoming uneven.

If you detect that the problem results from extreme heat, reducing hard braking will mitigate the problem. However, this won’t solve the issue completely.

You will need to use a power tool such as a lathe to ensure the brake disc’s surface is smooth.

If your diagnosis shows that the discs are warped, then you will need to get a replacement.

You should also be reading our article which talks about 5 Most Common Problems with Yamaha VMAX

Yamaha SMAX

The following are examples of the common problems with the Yamaha SMAX:

1. Faulty Speed Sensor

While this isn’t a preeminent problem, it did initiate a recall, so we’ll share it.

A few years ago, Yamaha recalled 2,640 scooters in the US alone due to an issue causing the speedometer to fail.

Yamaha announced this recall in Japan as well.

The issues had multiple steps, but the list of is was that the lead wire on the speed sensor wasn’t adequately fastened and was popping loose when the front wheel turned or when the front suspension was hit with heavy action.

The loosening of that lead speed sensor wire caused trauma to it, and over time the wires were breaking, so that and the broken wire prevented the vehicle speed from being read by the speedometer.

Yamaha dealers were called to action, upgrading the speed sensor assembly on recalled SMAX’s with two retaining clips versus the one clip used on the original speed sensor assembly.

If you bought your 2015 SMAX used and are unsure whether or not you’ve been upgraded, take it to Yamaha, and they’ll run the VIN and ensure you’ve got the latest installments.

2. Gasket May Leak

This problem is widespread on SMAX bikes, particularly those released between 2015 to 2018.

On the affected models, the gasket may fail and lead to coolant leaking into the cylinder.

If this happens, the spark plug may be doused in liquid, which would cause the engine to stall while riding.

Some signs that precede this problem are:

  1. Temperature warning signal comes up.
  2. Weird noises from the bike while idling
  3. Engine misfiring while the bike is idling

Yamaha reported that, on the affected scooters, the factory hadn’t properly tightened the cylinder head.

As the mopeds packed miles, these nuts started loosening, and the cylinder head followed, and, eventually, the gasket used to seal the cylinder failed.

As this happened, a few owners and mechanics found coolant leaks, and riders discovered the wet spark plugs to cause the engine to stalls riders had found common.

Yamaha prompted SMAX owners to make an appointment with their local dealership to change the head gasket and adequately screw-down the failing nuts, free of charge.

Yamaha maintained that the original nuts were not an issue but that the cause of the problem was a production line accident.

If you experience any of the aforementioned symptoms of a SMAX and you’re unsure if your bikes have been properly readjusted or not, it’s worth asking the Yamaha dealership about.

Yamaha TMAX

Here are some of the prevalent problems with TMAX:

1. Bike Hesitates Under Acceleration

This is a common problem with carburated bikes, including older Smax scooters and carburated scooters like it.

Hesitation or “bogging” refers to a situation where the engine misfires, stumbles, or lacks power.

Owners of TMAX bikes, especially early models, have complained about their mopeds hesitating under acceleration.

This is another issue that wasn’t isolated to a defect but has resulted from a few different maintenance mishaps.

The major cause of bogging or hesitation is an imbalance in the air-fuel ratio.

Combustion requires ignition, fuel, and oxygen. Combustion is maintained via the ignition of the spark plugs and the fuel and oxygen injection into the engine cylinder’s combustion chamber.

If the ratio particular to that engine design is off, bogging will occur, throttle response will suffer,  and acceleration will be affected.

This means there are two types of bogging:

I. Lean Engine Bog:

If the chamber gets too much air and not enough fuel, the motor will run “lean.”

A lean mixture is an air-fuel ratio that lacks fuel.

This will inevitably cause it to bog or hesitate when the rider tries to accelerate.

II. Rich Engine Bog:

If the bike gets too much fuel and not enough air, the engine will run “rich.”

A rich mixture is an air-fuel ratio too rich in fuel.

Should this happen, the scooter’s throttle response will slow-down and cause the engine to hesitate.

There are, however, other things that interfere with fuel on its way to the combustion chamber; it’s not always an improper air-fuel mixture that is to blame. If the fuel isn’t reaching the cylinder, acceleration will suffer.

Faulty or clogged-up fuel lines could restrict fuel flow to the chamber, causing sputtering and hesitation- bogging.

Possible causes of an engine bog include:

I. Faulty Throttle Position Sensor (TPS):

The throttle position sensor ensures the ratio of air to fuel in the engine is balanced.

If faulty, the engine will run rich (excess fuel) or lean (excess air).

Both cases will cause your motorcycle to hesitate under acceleration.

II. Air leaks (Intake Manifold, Vacuum lines, Throttle body):

Air leaks will cause the scooter engine to run lean, which may lead to the hesitation-under-acceleration problem.

A hole in your air filter will allow too much air into the engine cylinders, along with unwanted debris that could cause more severe problems.

III. Bad Fuel System Component

As this is a fuel-related problem, any faulty component in the motorcycle’s fuel system may be responsible.

For example, a jammed-up fuel filter will reduce the engine’s fuel and cause it to run lean. Similarly, a clogged-up air filter will restrict airflow into the engine and cause the engine to run rich.

IV.Bad fuel (Gasoline Contains Water or too much Alcohol):

According to reports from some owners, the Yamaha TMAX bikes don’t run well on gasoline containing ethanol (E10).

If you cannot afford regular fuel, then add fuel stabilizer liquid to your gas tank after filling up.

Yamaha makes its own brand of fuel stabilizers, which are available at retail outlets.

V. Dirty Carburator

If the bike is carbureted, something else to speculate when diagnosing engine power hesitation is the carburetor.

If smut or debris gets into the carburetor and hinders the jets, fuel issues will occur.

If this happens, the engine will likely hesitate next time you accelerate. A simple clean of the carburetor (including the jets) will solve the issue.

Notice that all these culprits are the result of wear and tear over time on an old scooter. These are normal issues to arise on a vehicle that doesn’t inspect and maintain its components regularly. Remember, keep up with the suggested service schedule in your owner’s manual to catch these problems before they occur.

2. TMAX Fever Issue

This one is rare, as in it doesn’t happen often, but it has received a fair share of attention for those times when it does.

The problem is thought to be caused by latent heat being trapped building up in the engine on hot days/long journeys.

If you don’t park the bike for long, likely, you won’t experience this problem.

But if you do, the chances of it happening to you increase.

Here’s a quick overview of the TMAX fever issue:

Typically, your engine will run hot if you ride in hot weather or ride for an extended amount of time. Parking the bike allows the engine to remain hot (since there’s no moving air to cool it); all the heat is now stuck in the body panels.

The theory is that trapped heat in the engine turns the gasoline in the fuel system into vapor, causing an old-fashioned case of “vapor lock.”

Once vapor lock occurs, the bike becomes impossible to start.

Vapor Lock Solution:

This one’s a little sketchy, but if your vehicle has been experiencing vapor lock and you have no choice but to park it hot, pop the gas cap if you’re parking the bike hot on a warm day, and the open-air will cool the gas before it vaporizes.

General Pros and Cons of TMAX/SMAX/VMAX

Pros of the Yamaha TMAX/SMAX/VMAX

Here are qualities of the Yamaha TMAX/SMAX/VMAX:

1. Comfortable to Ride:

The trio of Yamaha’s maxi-scooter offerings provides optimal comfort for riders of any size.

In fact, bikes are designed to be comfortable for even vertically challenged individuals.

A good example is the XMAX, which comes with a sculpted seat that doesn’t cut into the rider’s thighs.

2. Delivers Decent Performance:

Yes, scooters are the least powered models in the motorcycle segment.

However, Yamaha’s maxi-scooters offer decent power for quick rides in the city.

Take the SMAX, for example. It comes with a 155cc engine that produces 80 mph and 85 mph with a good tailwind.

That’s enough power to allow you to dash around the city with ease.

3. Ample Storage Space:

While they aren’t bagger models, the maxi models offer some cargo-holding capacity.

For example, the TMAX comes with glove boxes to keep papers, glasses, snacks, and phones.

It also has an under-seat storage compartment where you can store items.

You could even turn the scooter into a mini-bagger model by buying the optional rear storage case.

Cons of Yamaha TMAX, XMAX & SMAX

Here are examples of common issues with the Yamaha MAX scooters:

  1. The scooter won’t start.
  2. Warped Front Brake Discs
  3. Faulty Speed Sensor
  4. Gaskets May Leak
  5. Bike Hesitates Under Acceleration
  6. TMAX Fever Issue

What Do the Reviews Say?

“Jumping into the maxi-scooter market both feet first, the Yamaha TMAX is a sporty machine aimed at aggressive riders who demand power and handling. With 15-inch Dunlop Sportmax tires and a 62.2-inch wheelbase, the TMAX is ready for high-speed riding, as well as prepared to do business in urban environments.”


What’s The Resale Value On the Yamaha TMAX, XMAX & SMAX?

Model Year Mileage Price ($)
Yamaha TMAX 2009 16,563 3,495
Yamaha TMAX 2015 11,000 7,000
Yamaha SMAX 2017 4,691 3,928
Yamaha SMAX 2018 1,800 2,999
Yamaha SMAX 2015 1,350 2,499
Yamaha XMAX 2018 23,189 4,990
Yamaha XMAX 2018 3,744 3,999
Yamaha XMAX 2019 501 4,788
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ⓘ  The information in this article is based on data from National Highway Traffic Safety Administration (NHTSA) recall reports, consumer complaints submitted to the NHTSA, reliability ratings from J.D. Power, auto review and rating sites such as Edmunds, specialist forums, etc. We analyzed this data to provide insights into the best and worst years for these vehicle models.