8 Common Triumph Street Twin 900 Problems (Explained)

The Triumph Street Twin 900 is a stylish, modern classic blending contemporary technology with a vintage café racer style.

However, like any other machine, the Street Twin 900 isn’t perfect and may develop problems.

This article discusses some of the issues that affect the Street Twin 900 and the solutions on how to fix or prevent them.

1. Squeaking Front Suspension Forks

Some Street Twin owners have reported that their front suspension forks make a squeaking sound like an old metal bed with springs. This could be due to the forks being pinched or bowed at the bottom, causing the springs to rub inside the tubes.

In some cases, this problem comes from the factory or from improper fork installation or adjustment. In others, an overtightened front axel bolt is to blame.

“My forks started making this squeaking sound because the front axle bolt was over-tightened; this didn’t start happening until the dealer installed my new windshield and had to remove the forks to install it, so this one probably wasn’t the bike’s fault.” -newbonnevilleriders.com

To prevent your fork from squeaking on your Triumph Street Twin 900, check the alignment and tension of the forks, ensuring it’s neither too tight nor too loose.

• Start by loosening the pinch bolts on the lower fork legs and the axle nut and then rotating the wheel back and forth while holding the front brake, settling the forks in their natural position.
• Next, you can tighten the pinch bolts and the axle nut to the specified torque.
• Lubricate the fork seals and springs with a Triumph-recommended grease or oil to reduce friction and noise.
• If the problem persists, you may need to replace the fork springs or tubes.

Take your bike to a Triumph-qualified mechanic for a front suspension, fork, wheel, and axel inspection.

2. Hard to Start

Some Street Twin owners have reported that their bike is hard to start, especially on the first attempt. This problem may be caused by low battery voltage, faulty fuel injection, or incorrect engine mapping.

Here’s what a few riders on newbonnevillerider.com reported regarding hard or no starts on their Street Twin 900s:

“Hard to start after 500-mile service. It would start, then idle down, and then shut off; it would take four attempts before it would stay running. The dealer said it needed the North American tune, but they made it worse, so the dealer suggested I put the Vance and Hines exhaust on to use the performance tune. It is better now. It only takes 2 or 3 tries.”

“My 2016 Street Twin wouldn’t stay running on a cold start, as others have mentioned. It would stall out, and it’d take two or three cranks before it would idle. Fuel injection shouldn’t do that in my mind.”

To solve and prevent hard starting on a Triumph Street Twin 900:

• Check and charge your battery regularly. At the very least, according to the maintenance schedule Triumph outlines in your Owner’s Manual.
• Inspect your fuel injection system and clean it as needed.
• Have your local Triumph dealership tech run CPU diagnostics, flashing your ECU with the correct code for your bike and region as needed.
• Use the correct starting procedure for your Street Twin, as the manual suggests.

3. Faulty Chain Adjuster

Some Street Twin owners have reported that their chain adjuster was maxed out when they bought the bike, meaning they had no room to tighten or loosen the chain as needed.

An improper factory adjustment could cause the chain to be too slacked or loose, affecting the performance and safety of the bike.

The problem persisted until Triumph replaced some chains for free and removed some links from the new ones to give some adjustment range.

“The drive chain adjuster was maxed out when I bought it, and Triumph ended up replacing the chain, and even with the new chain, they had to remove two links.” – newbonnevilleriders.com

“The Chain Tensioner for the drive chain was maxed out after going back and forth with the dealer pointing out that my bike only had 500 miles and that they should fix it by taking out a couple of links and then pointing out that all of the new Street Twins they had had the same issue they finally agreed to help just to shut me up.” – newbonnevilleriders.com

To adjust the chain tension, you should follow these steps:

• Loosen the rear axle and lock nut on each side of the swingarm.
• Turn the adjuster bolts, usually counter-clockwise, extending the bolt “outward” to lengthen the chain and make it tighter.
  • Sometimes, you’ll want to increase the slack to make the chain looser — in those cases, turn it clockwise / inward)
• Make sure to adjust the bolts the same amount on each side — check the markings.
• Inspect the chain tension again and repeat until it is within the specified range.
• Tighten the lock nut on each side of the swingarm and the rear axle nut to the specified torque.
• Check the wheel alignment and make sure it is not crooked or misaligned.

You can do this yourself or take your bike to a Triumph-literate mechanic for assistance.

4. Bike Leaks Oil

Street Twin 900 owners often report that their bike leaks oil from various parts, such as the head gasket, the water pump, the gear position sensor, the sprocket cover, or the oil filter.

Oil leaks can cause performance and safety issues and risk damage to the engine and other components.

Various factors, such as faulty seals, gaskets, or O-rings, improper installation or adjustment of parts, or excessive pressure or temperature, can cause oil leaks.

“Oil started leaking from the valve covers, and my dealer accused me of taking the cover off and putting red sealant on the gasket; I explained to the dealer I didn’t have any tools to do this and asked them why the hell I would mess with anything on a bike still under warranty.

The bike only has 3600 miles, and I only use it to commute to work on nice days and to ride with friends on the weekend; I have been told by the dealer that mine is the exception and that no one else has had these issues and they think my bike must have been assembled on a Friday and that quality control was lax during and after assembly.” – newbonnevilleriders.com

To fix and prevent oil leaks on a Triumph Street Twin 900:

• Find where the oil is leaking from. Use a flashlight, mirror, or paper towel to check the engine and nearby areas. Use baby powder or talcum to make the oil more visible.
• Replace any faulty seals, gaskets, or O-rings. Look for these parts in the manual or online. Common parts are the head gasket, water pump seal, gear position sensor gasket, or oil filter seal.
• Adjust the torque and alignment of any parts. Use a torque wrench and ruler to tighten and align them. Typical parts are the cylinder head bolts, sprocket cover bolts, or rear axle nuts.
• Clean the oilways and passages. Use compressed air or pipe cleaner to blow out any dirt. Common areas are the cylinder block, head, water pump, or gear position sensor.
• Change the oil and filter regularly. Use quality oil and filter for your bike. Avoid overfilling or underfilling the oil.

5. Fuel Leaks from Gas Tank

A somewhat less common issue reported by Street Twin riders is that the bike leaks fuel from the gas tank onto the cylinder heads. This severe and dangerous problem could cause fire, engine damage, or injury to the rider.

Faulty seals, valves, hoses, caps, improper installation or adjustment of parts, or excessive pressure or temperature can all cause fuel leaks.

“Fuel leaking from [my Triumph Street Twin 900’s] gas tank onto the cylinder heads. The dealer should have fixed this since the recall was sent out in January, and I bought the bike in March, especially since I specifically asked the dealer if it was fixed when I bought the bike, and I was assured it was.” – newbonnevilleriders.com

To repair and prevent fuel leaks on a Triumph Street Twin 900:

• Find where the fuel is leaking from. Use a flashlight, mirror, or paper towel to check the gas tank and nearby areas.
• Replace any faulty seals, valves, hoses, or caps. Look for these parts in the manual or online. Typical parts are the fuel tank seal, breather valve, fuel line hose, gas cap, or gas cap seal.
• Use a torque wrench and ruler to tighten and align loose fuel system fasteners. Standard parts are the fuel tank bolts, gas cap bolts, or fuel line clamps.
• Clean the fuel system and passages. Use compressed air or pipe cleaner to blow out any dirt. Common areas are the fuel tank vent, fuel filter, or injectors.

Use quality fuel for your Street Twin and avoid overfilling or underfilling the gas tank.

6. Faulty Wiring Harness

More than a few Street Twin owners experienced a faulty wiring harness that caused starting failure or engine stalling.

This was due to the wiring harness being misrouted and interfering with the handlebars, causing damage and short circuits.

• Triumph issued a recall and offered to fix or replace the wiring harness for free.
• Check if your bike is affected by the recall.
• You can use the VIN checker on the Triumph website or contact your local Triumph dealer to see if your bike is eligible for the recall service.
• Book an appointment with your Triumph dealer as soon as possible. They will inspect and repair or replace your wiring harness for free.
• The recall also requires the techs to install a VIN plate protector that reroutes the harness and prevents it from rubbing the lower lug on the main frame headstock.

7. Engine Gets Too Hot

Another issue multiple Street Twin 900 owners reported is that the engine gets too hot, especially when idling at standstills, sometimes making the rider uncomfortable.

To fix and prevent engine overheating on Triumph Street Twin 900s:

• Find the cause of the overheating. It could be a defective water pump, faulty wiring, faulty radiator, bad coolant, or lubricant leak.
• Replace your water pump if it is faulty or leaking.
• Repair your wiring harness if it is damaged or misrouted.
• Clean your radiator if it is dirty or clogged.
• Refill your coolant if it is low or wrong.
• Change your coolant if it is low or contaminated.

8. Bike Vibrates, Sputters, or Stalls

Some Street Twin owners have reported that their bike vibrates, sputters, or stalls at various speeds or conditions.

If your Triumph Street Twin 900 experiences harsh vibration, sputtering, or stalls while riding, it could be due to corroded, cracked, or fouled spark plugs, faulty ignition coil, damaged or misrouted wiring harness, or outdated engine mapping.

Here is what some owners on newbonnevilleriders.com had to say about the situation:

 “As my [Street Twin] coasted down to about 55, the front handlebars started shaking. I mean violent shaking. The bar ends were a blur, moving at least 5 inches back and forth… I felt like if I hadn’t grabbed them within a nano-second, I was going to have some major issues keeping the bike upright. Once I grabbed them, everything calmed down; just the little damper effect of holding them brought them back to normal. Still… this isn’t how a new bike should behave.”

“Well, I’ve got 11,000 miles on [My Street Twin 900], and now it is stalling at traffic lights and sputtering when I take off; the damn thing shutoff at a stop light this past weekend, and I could get it started back up until it cooled off and I had to keep the throttle cracked open all the way home because it acts like it is going to die when I let it idle down.”

To fix and prevent bike vibration, sputtering, or stalling, you should:

• Find the cause of the problem:
  • Replace your spark plugs if corroded, cracked, or fouled.
  • Replace your ignition coil if it is faulty or damaged.
  • Repair your wiring harness if it is damaged or misrouted.
• Update your engine mapping with the Triumph Autoscan software. Your dealer can do this for you in well under an hour. This will improve your bike’s performance and fuel injection system.

What Are the Pros and Cons of the Triumph Street Twin 900?

Pros

• Modern Retro Style
• Torquey, Punchy Motor
• Smooth Performance
• Fun to Ride
• ABS, Traction Control, Varying Ride Modes
• Low Seat Height; Accessible to Rider of Different Builds
• Great for Beginners and Fun for Pros
• Power Restricted Version Available for Riders Still Learning

Cons

• Faulty Wiring Harness
• Engine Gets Too Hot
• Bike Vibrates, Sputters, or Stalls
• Squeaking Front Suspension Forks
• Hard to Start
• Faulty Chain Adjuster
• Bike Leaks Oil
• Fuel Leaks from Gas Tank

What Do the Reviews Say?

– “The Triumph Street Twin will continue the success of the previous model. It does everything you want from a modern classic naked roadster, but now with improved braking, comfort, safety, and more importantly, performance.”

– “The increase in power and more significantly, the mid-range grunt has increased the appeal of the Street Twin and injected some excitement to the bike while still retaining its ease-of-use and rider-friendliness.”

– “The new ‘slip assist’ clutch is far lighter than the previous-generation Bonnie’s, and the five-speed gearbox is slick and precise.”

– “The single disc twin-piston Nissin brake set-up has impressive feel and power, too.”

– “The Triumph has an 18” front wheel for retro looks, which takes a bit of getting used to after 17 inches, so the front end needs more muscle to get into a corner, but once you’re in and powering through the Street Twin is completely stable.”

– “The Street Twin handles brilliantly. The 198kg (dry) machine is light, agile, has excellent full lean stability and acres of ground clearance.”

– “The Street Twin is agile around town and offers a plush ride. A well-padded seat and relaxed riding position enhances comfort and lets you ride all day with no aches or pains.”

What’s the Resale Value of a Triumph Street Twin?

What Are Some Alternative Models?

Sources:

TRIUMPH STREET TWIN (2019 – on) Review | MCN (motorcyclenews.com)

TRIUMPH STREET TWIN (2016-on) Review | Specs & Prices | MCN (motorcyclenews.com)

Triumph Street Twin (2021+) Maintenance Schedule / Service