Kawasaki W650 Problems

The Kawasaki W650 has earned a reputation as a reliable retro motorcycle with classic styling and character. Still, like any bike, it’s not free of quirks and recurring issues that owners should know about. Whether you’re considering buying a W650 or looking to keep your own running strong, it pays to be aware of the common problems and what to look out for.

Starter Clutch and Cranking Issues

One of the most widely discussed problems on the W650 is with the starter clutch. Owners report that over time, the starter clutch mechanism can wear out, resulting in a clattering or whirring noise when the starter button is pressed, without the engine turning over. In some cases, the starter will spin but not engage the engine, especially on cold starts or after the bike has sat for a period. This issue is often due to worn rollers or springs inside the starter clutch assembly.

Replacement parts are available, but the job is labor-intensive and requires splitting the right-side engine cover. Some riders choose to live with the occasional slip, but consistent issues mean it’s time to address the fault to avoid a no-start situation. Regular oil changes and using the correct viscosity can help prolong the life of the starter clutch, but there is no permanent preventative fix besides replacing the worn parts when symptoms appear.

Camshaft Oil Feed and Ticking Noise

W650 owners sometimes notice a persistent ticking or tapping noise from the top of the engine. This is often traced to the camshaft oil feed system. The W650 uses an internal oil pipe to supply lubrication to the camshafts and valve rockers. If the oil feed gets partially blocked or the seals degrade, camshaft wear can occur, leading to increased valvetrain noise.

Checking and cleaning the oil pickup and lines during major services can prevent this problem. If you hear pronounced ticking, inspect the valve clearances first, then look into oil delivery if clearances are within spec. Neglecting this can cause premature camshaft or rocker arm wear, which is a more expensive repair. Switching to a quality oil filter and ensuring regular oil changes further reduces risk.

Carburetor Issues and Rough Running

The W650’s twin carburetors are generally robust, but as the bikes age, they’re a frequent source of headaches. Common issues include sticky float valves, leaky carb boots, and blocked jets, all of which can cause uneven idling, hesitation, or hard starting. Ethanol-blended fuels can accelerate the degradation of fuel system rubber parts and contribute to clogging.

Symptoms of carb trouble include poor cold starting, erratic idle, or surging at low throttle. A thorough carb clean and re-synchronization often restores smooth operation. Inspect intake boots for cracks and replace if necessary. Fitting inline fuel filters helps keep debris out of the carbs, and running the bike regularly prevents fuel from turning gummy inside the bowls. Some owners re-jet the carbs for improved throttle response, but correct jetting demands careful tuning.

Electrical Gremlins and Charging System

Electrical reliability is generally good, but a few weak points have been reported. Aging wiring harnesses can develop corrosion at connectors, especially near the headlight, leading to issues with lighting or starter circuits. Another recurring issue involves the charging system - specifically, the regulator/rectifier can overheat and fail, resulting in a flat battery or erratic charging voltage.

If you experience dimming lights or sluggish cranking, check the voltage across the battery terminals at idle and at 4000 rpm. Anything below 13V at speed suggests a charging problem. Installing a modern, more robust regulator/rectifier is a popular long-term solution. Also check the battery itself, as a weak or old battery can exacerbate starting and charging complaints.

Rust and Corrosion on Chrome and Fasteners

The W650 sports lots of exposed metal, polished alloy, and classic chrome. Unfortunately, these surfaces are vulnerable to corrosion, especially if the bike is stored outdoors or ridden through winter. Chrome on fenders, exhausts, and mirrors can pit and rust, while engine cases can oxidize and become dull.

Regular washing and drying, followed by the application of a corrosion inhibitor like ACF-50 or WD-40, helps keep rust at bay. Inspect fasteners and brackets for surface rust, and replace or treat them as needed. Pay special attention to hidden areas: under the tank, behind side covers, and beneath the seat are all prone to unnoticed corrosion. Re-chroming pitted parts is possible but expensive; prevention is much cheaper.

Gearbox Quirks and Shifting Feel

The W650’s 5-speed gearbox is generally solid, but some owners find the shift action clunky or notchy, particularly between first and second gear. False neutrals are occasionally reported, especially on bikes with worn linkage or after a missed shift. While outright gearbox failures are uncommon, the feel can be less precise than modern transmissions.

Shifting improves when the oil is fresh and at the correct level. If you notice missed shifts or difficulty going into gear, check the external shift linkage for play and lubricate the pivot points. If problems persist, internal wear in the shift drum or selector forks could be the cause, but this is unusual outside of high-mileage or abused examples. Adjusting your shifting technique and not rushing changes reduces missed gears.

Valve Clearance Maintenance

Valve clearance checks are required every 7,000 to 8,000 miles on the W650. The engine uses screw-and-locknut adjusters, which makes the job straightforward for the experienced home mechanic. However, skipping scheduled checks can lead to tight valves, poor starting, and eventually, valve seat damage. The parallel twin design means the exhaust valves, in particular, are prone to closing up over time.

Signs that your clearances are out of spec include hard starting when cold, rough idle, or a loss of compression. Always follow the factory service manual for clearances and adjustment procedure. Keeping records of adjustment history helps with resale and ensures long-term reliability. If you’re not confident, a reputable shop can perform the check at reasonable cost.

Frequently asked questions