Yamaha TT600 Problems: 6 Known Issues (Explained)

The TT600 is a stripped-down, straightforward, single-cylinder, four-stroke enduro bike released by Yamaha in 1998.

The TT600 won over critics with its performance in several off-road riding competitions. While it’s no longer in Yamaha’s current lineup, used versions are cheap and offer great value.

Part of the praise for these bikes is owed to their simplicity; these bikes were simple and easy to work on, and there are owners out there who’ve worked on their’s plenty.

We’ve come to shine a light on some of the more challenging garage stories we’ve picked up about the Yamaha TT600 series.

Let’s hit it!

1. Faulty CDI Problem

First things first. The TT600 is a refresh on a series of enduro bikes Yamaha produced in the ’80s called the XT series.

The TT600 is often confused with the XT600, so we’d thought we’d take this opportunity to clear the air on a confusion we’ve seen pop up on various forums.

The Faulty CDI bo problem was an issue with the TT600’s predecessor, not an issue with the XT600.

The CDI box controls a motorcycle’s ignition system and allows it to start properly. “CDI box” is short for the Capacitor Discharge Ignition box, although it is also called thyristor ignition box.

The CDI uses voltage from the motorcycle battery to start the ignition and combustion processes. When you press the starter, voltage passes through the CDI box and fires up the spark plug.

Yamaha XT600 bikes had troubles with the CDI system, particularly those released between 1982 and 1996. They made adjustments before launching the TT600, and the results have proven successful,

If the CDI box fails to work, it’s likely the bike won’t run at all.

Here are some of the problems owners have reported:

1. The bike is difficult to start.
2. The bike starts when cold but cannot restart when the engine is warm.
3. Exhaust pipes get extremely hot.
4. The bike runs well at the bottom end but does not rev out.
5. Engine misfires (and stalls on occasions)
6. Multiple ignition problem

From reports, the CDI problem on the TT600 bikes is due to a design defect.

The TT600 uses a single-sided circuit board and not the through-hole plating. The latter method efficiently secures components to the circuit board, unlike the former.

The CDI unit has a resin, which often heats up and expands. Should this happen, the resin will pull on components, breaking the solder tabs. It can also pull on the legs of the components, causing their pads and leads to touching. If this goes on for long, the CDI unit will eventually fail.

Another likely cause for the failure of the CDI box is operation hazards. While you ride, your bike’s CDI box is exposed to high levels of vibration and heat. Over time, components can wear out and cause the CDI system to fail.

If you detect CDI box failure on your bike, be prepared to part with some cash. Because the CDI box is designed to be maintenance-free, you cannot try fixing the malfunctioning CDI component. Rather, you will have to replace the entire box.

We will advise that you should confirm if replacing the CDI will fix the problems described earlier.

A bad stator, regulator/rectifier, battery, or loose wiring may be responsible. We advise that you err on the side of caution and have a technician look over your bike.

2. Swingarm May Crack

The swingarm is a major part of the rear suspension on motorcycles. It helps hold the rear axle firmly and allows the suspension to soak up bumps in the road.

Also, it affects the bike’s center of gravity, which influences handling and rider balance.

If the swingarm is deformed (cracked or bent), handling and balance will be affected severely. One such swingarm-related problem is a “speed wobble.”

Moreover, the bike may jerk when it goes over bumps in the road. This will cause rider discomfort and makes for less-than-ideal riding experiences.

We’ve encountered a few cracked swingarms on TT 600s, but that’s not uncommon for an enduro bike. These are trail bikes, and the suspension system is designed for such riding; they’re not crash-proof. Jumping rocks and hitting hard ground with enough force can put in a crack in the swingarm of even the toughest adventure bikes.

Subject to the deformity’s severity, you can either weld the swingarm or get a new one.

It is advisable to have a technician inspect the swingarm before you decide, as welding a swingarm that’s past the point of repair is not only dangerous but could cause the bike more damage down the road.

3. Bike Doesn’t Start Properly

Because these bikes are old, they often have issues starting in cold weather. Like its predecessor, the TT600 models used carburetion, and carburetted bikes are notorious for starting in frosty weather.

Modern bikes use fuel injection. Like the name implies, fuel injection spits fuel directly into the combustion chamber, making ignition more reliable in cold or wet weather.

If your Yamaha TT600 is having issues starting on wintry mornings, don’t fret, as this behavior is normal.

One pro tip on starting a carbureted bike in the cold is to pull the choke. Let the bike warm up by idling it for at least 5 minutes with the choke pulled out, push your choke in before you take off, and let it rip!

Here are some ways you can prevent cold start problems on your TT600:

• Store it in a climate-controlled garage: This will keep it warm and allow it to start easily next time.
• Use dry gas: Riders can add dry gas to the tank to prevent fuel lines from freezing. Sometimes, frozen fuel lines may be responsible for cold start problems. If the fuel lines are frozen, they won’t be able to supply fuel to the motorcycle’s engine, which will make it impossible to start the bike. Note: This is for running a bike in temperatures below freezing.

4. Bike Smokes On Startup

Another problem of the TT600 is what owners describe as an “engine smoke” problem. Some TT600 owners say smoke pours out when they try to start their bikes. This is another section we can attribute to wear and tear on an old bike.

According to TT600 owners, the smoke is usually of a blue-white color and is accompanied by a smell of burning oil. The smoke usually clears out some minutes after startup, particularly when the bike reaches cruising speed.

Most diagnoses conducted by owners traced the problem to failed valve stem seals.  These seals prevent oil in the valve cover from entering the engine’s combustion chamber.

Although they are made to last, these valves may wear out, crack, or break over time. If this happens, they will lose their ability to direct oil flow. Afterward, the oil will flow from the cylinder head to the combustion chamber.

You may also like to explore our article about 6 Most Common Problems With Yamaha TMAX, XMAX & SMAX

When you ignite the motorcycle, fuel, air, and oil will mix. This causes the burning oil smell and the smoke that pours out from the exhaust pipe at startup. 

This problem isn’t necessarily severe as the smoke disappears once you start riding, but it’s only a matter of time before broken seals get worse and affect the bike’s performance. To keep your bike’s life long, to keep the smell of smoke off your clothes, it is advisable to get new valve stem seals.

5. Engine Backfires Or Misfires While Riding

A misfire and backfire are different symptoms of a similar issue; both are consequences of an imbalance in the air-to-fuel ratio.

A misfire happens when the engine runs lean (too much air), while a backfire happens when the engine is running rich (too much fuel).

With a misfire, the engine makes a popping/banging sound followed by a loss of power.

A backfire, on the other hand, is a popping sound from the motorcycle’s exhaust. Like the misfire, this is often followed by a decrease in power.

Securing the proper air: fuel ratio takes regular maintenance and routine service; as on any older bike, misfiring and backfiring are quite common on TT600 models that haven’t been serviced in a while.

Here are some causes of engine misfires and backfires on the TT600 models:

• Dirty spark plugs
• Clogged fuel lines
• Clogged air filters
• Bad fuel pumps

6. Multiple Battery Problems

Some TT600 owners have complained about the performance of the batteries on their bikes.

The reports seem the battery often fails to charge or cannot hold a charge (and drains rapidly). A particular rider complained that his bike died after some miles, even though he’d charged it before.

In worse cases, the bike doesn’t start at all.

Potential causes range from a faulty stator to a failed regulator or starter. While you can test the electrical system to detect what’s wrong, we’ll advise you not to.

Instead, have a technician conduct a thorough examination of your bike’s electrical system and recommend a solution.

General Pros and Cons of the Yamaha TT600

Here are some of the advantages and disadvantages of the Yamaha TT600:

Pros Of Yamaha TT600

1. Reliable Engine:

The Yamaha TT600 comes with a simple air-cooled four-stroke engine that is easy to maintain.

Moreover, its air-cooled nature means fewer moving parts, which equals fewer chances for something to break down. The models have a recommended 6000-mile maintenance interval, which is impressive.

The engine itself is no slouch, and the bike is suitable for quick trips around town.

The engine produces a decent 37 back-wheel bhp and offers an appreciable amount of torque as well. This allows the TT600 to perform well, even on dirt tracks.

2. Good Ride Quality:

Owners have given positive comments concerning the TT600’s ride quality.

According to them, the bike is comfortable enough to be used for in-town rides.

If you’re looking for a budget city-friendly bike, the TT600 is an advisable option.

3. Offers Superior Value:

The TT600 is a great investment for anyone looking for a cheap enduro bike.

It has low running costs and depreciates slowly, which means your purchase will remain valuable for longer.

4. Versatility:

Although it is more geared toward off-road riding, the TT600 can handle city riding with ease.

Cons Of Yamaha TT600

The following are common issues with the TT600:

1. Faulty CDI Problem
2. Swingarm May Crack
3. Bike Doesn’t Start Properly.
4. Bike Smokes On Startup
5. Engine Backfires Or Misfires While Riding
6. Recurrent Battery Problems

What Do the Reviews Say?

“With its low price, air-cooled, four-stroke motor, and simple chassis, the Yamaha TT600R represent the utilitarian side of modern biking. It does have some off-road pretensions, but it’s most at home pressed into the role of a tough urban commuter. On the flip side, the Yamaha TT660R turns motorways into instruments of torture.”

[Source: Motorcyclenews.com]

What’s The Resale Value On the Yamaha TT600?

Note: You may have to import these bikes into the US.

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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.