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December 17, 2010 by 1 Comment

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Filed Under: Troubleshooting Guides

Spark Plug Troubleshooting

January 12, 2010 by

Spark Plug troubleshooting rich lean running condition fouling burning

 

NGK Spark Plug Letter Code Spark Plug Socket Size
B 13/16 in or 21 mm
C 5/8 in
D 18 mm
Filed Under: Troubleshooting Guides

Two-Stroke Motorcycle Troubleshooting Guide

July 15, 2009 by Leave a Comment

NOTE:
This is not a comprehensive list, giving every possible

cause for each problem listed. It is designed as a general guide to assist in troubleshooting some of the

more common problems encountered. Also check out the spark plug troubleshooting guide from the good folks at NGK.

Engine Doesn’t Start; Starting Difficulty:

Engine won’t turn over:
Piston seizure

Crankshaft bearing seizure

Connecting rod small end seizure

Connecting rod big end seizure

Transmission gear or bearing seizure

Kick shaft return spring broken

Kick ratchet gear not engaging

No fuel:
No fuel in tank

Fuel tank vent blocked

Fuel tap turned off

Fuel tap clogged

Fuel line clogged

Float valve clogged or stuck closed

Engine flooded:
Fuel level too high

Float valve worn or stuck open

Starting technique incorrect
(when flooded, kick with the throttle wide open to allow

more air to reach the engine.)

No spark; weak spark:
Spark plug fouled, broken, or misgapped

Spark plug cap or high tension wiring faulty

Spark plug cap not in good contact with spark plug

CDI unit faulty

Ignition coil faulty

Magneto damaged

Loose wire connector

Engine stop switch stuck closed

Air/fuel mixture incorrect:
Idle air screw mis-set

Slow jet or air passage clogged or restricted

Air cleaner clogged, poorly sealed, or missing

Starter jet clogged or restricted

Incorrect fuel level

Incorrect jet sizes

Low compression:
Spark plug loose or damaged threads

Cylinder head nuts not torqued properly

Cylinder, piston or rings worn or broken

Piston ring/land clearance excessive

Cylinder head gasket not sealing

Cylinder head warped

Cylinder base gasket not sealing

Cylinder nuts not torqued properly

Reed valve damaged

Poor Running at Low Speed;

Weak spark:
Spark plug fouled, broken, or misgapped

Spark plug cap or high tension wiring faulty

Spark plug cap not in good contact with spark plug

Spark plug incorrect

CDI unit faulty

Ignition coil faulty

Magneto damaged

Loose wire connector

Ignition timing not set properly

Air/fuel mixture incorrect:
Idle air screw mis-set

Slow jet or air passage clogged
or restricted

Air filter clogged, improperly installed or missing

Starter plunger stuck open

Fuel tank vent blocked

Intake manifold clamp loose

Air cleaner duct loose

Incorrect fuel level

Incorrect jet sizes

Low compression:
Spark plug loose or damaged threads

Cylinder head nuts not torqued properly

Cylinder, piston or rings worn or broken

Piston ring/land clearance excessive

Cylinder head gasket not sealing

Cylinder head warped

Cylinder base gasket not sealing

Cylinder nuts not torqued properly

Reed valve damaged

Other:
Drive chain misadjusted

Drive chain not lubricated

Wheel bearings faulty

Brakes dragging

Tire air pressure too low

Poor Running at High Speed:

Incorrect Spark
Spark plug fouled, damaged, or misgapped

Spark plug cap or high tension wiring damaged

Spark plug cap not in good contact with spark plug

Spark plug incorrect

CDI unit faulty

Ignition coil faulty

Magneto damaged

Loose wire connector

Ignition timing not set properly

Air/fuel mixture incorrect:
Main jet restricted or wrong size

Jet needle worn

Jet needle clip in wrong position

Fuel level incorrect

Air jet or air passage restricted

Air filter dirty, improperly installed, or missing

Starter plunger stuck open

Fuel flow to carburetor insufficient

Water or dirt in fuel

Fuel tank vent blocked

Intake manifold clamp loose

Air cleaner duct loose

Low compression:
Spark plug loose or damaged threads

Cylinder head nuts not torqued properly

Cylinder, piston or rings worn or broken

Piston ring/land clearance excessive

Cylinder head gasket not sealing

Cylinder head warped

Cylinder base gasket not sealing

Reed valve damaged

Cylinder nuts not torqued properly

Engine does not rev up properly:
Starter plunger stuck open

Fuel level incorrect

Main jet clogged, restricted or wring size

Throttle valve does not fully open

Air filter dirty

Muffler or exhaust port restricted with carbon deposits

Water or foreign matter in fuel

Brakes dragging

Drive chain misadjusted

Ignition timing not set properly

Overheating

Transmission oil level too high

Transmission oil

viscosity too high

Crankshaft bearing worn or damaged

Knocking:
Carbon built up in combustion chamber or on piston crown

Pre-mix not correct

Low octane fuel

Spark plug not correct

CDI unit faulty

Ignition timing not set properly

Overheating:

Ignition problem:
Spark plug fouled, broken, or misgapped.

Spark plug

incorrect

CDI unit trouble

Ignition timing not set properly

Air/fuel mixture incorrect:
Main jet clogged, restricted or wrong size

Fuel level in carburetor too low

Intake manifold clamp loose

Air filter not installed properly or missing

Air filter duct poorly sealed

Compression high:
Carbon built up in combustion chamber

Carbon built up on piston crown
Aftermarket high compression piston

Excessive engine load:
Brakes dragging

Clutch slipping

Transmission oil level too high

Transmission oil viscosity too high

Drive chain misadjusted

Tire air pressure too low

Inadequate lubrication:
Pre-mix incorrect

Transmission oil level too low

Transmission oil poor quality or incorrect type

Incorrect coolant:
Coolant level too low

Coolant old

Coolant not mixed properly

Cooling component problems:
Radiator clogged

Radiator fins damaged

Radiator cap faulty

Water pump not working

Coolant passageways restricted

Clutch Not Working Properly:

Clutch sipping:
Inadequate clutch lever free play

Clutch cable misadjusted or not working smoothly

Friction plates worn

Steel

plates warped

Clutch springs broken or worn

Clutch

release mechanism sticking

Clutch hub or housing

worn

Clutch not disengaging properly:
Excessive clutch lever free play

Clutch cable misadjusted or not working smoothly

Clutch steel plates warped

Clutch spring

tension uneven

Transmission oil deteriorated

Transmission

oil viscosity too high

Transmission oil level too high

Clutch housing bearing seized

Clutch release

mechanism faulty

Gear Shifting Problems:

Doesn’t go into gear; shift lever doesn’t return:
Clutch

not disengaging

Bent shift shaft

Shift fork bent or seized

Gear seized on

the shaft

Gear positioning lever binding

Shift return

spring weak or broken

Shift return spring pin loose

Shift

mechanism arm spring broken

Shift mechanism arm broken

Shift drum broken

Jumps out of gear:
Shift fork worn or bent

Gear groove worn

Gear dogs and/or dog holes worn

Shift drum groove worn

Gear positioning lever spring weak or broken

Shift fork guide pin worn

Drive shaft, output shaft, and/or gear splines worn

Incorrectly positioned transmission snap ring

Overshifts:
Gear positioning lever spring weak or broken

Shift mechanism arm spring broken

Abnormal Engine Noise:

Knocking:
CDI unit faulty

Carbon built up in combustion chamber or on piston crown

Poor quality fuel or incorrect pre-mix

Spark plug incorrect

Ignition timing not set properly

Overheating Piston slap:
Piston to cylinder clearance excessive

Cylinder or piston worn

Connecting rod bent

Piston pin or piston pin holes worn

Other noise:
Connecting rod small end clearance excessive

Connecting rod big end clearance excessive

Piston ring worn, broken or stuck

Piston seizure or other damage

Cylinder head gasket leaking

Exhaust pipe leaking at cylinder head connection

Crankshaft runout excessive

Engine mounts loose

Crankshaft bearings worn

Primary gear worn or chipped

Abnormal Drive Train Noise:

Clutch noise:
Clutch housing to friction plate clearance excessive

Clutch housing gear to primary gear backlash excessive

Metal chip jammed in clutch housing gear teeth

Transmission noise:
Transmission bearing worn or damaged

Transmission gear worn or chipped

Metal chip jammed in gear teeth

Transmission oil insufficient or incorrect

Kick ratchet gear not properly disengaging from kick gear

Drive chain noise:
Chain adjusted improperly

Rear wheel misaligned

Chain not lubricated

Chain worn

Worn sprockets

Missing teeth from sprockets

Abnormal Frame Noise:

Rear shock absorber noise:
Shock absorber damaged

Loose fasteners

Disc brake noise:
Pads installed incorrectly

Pad surface glazed

Disc warped

Caliper faulty

Master cylinder damaged

Loose fasteners

Other noise:
Bracket nut, bolt, etc. not properly mounted or tightened

Exhaust Smoke:

Excessive white smoke:
Throttle cable misadjusted

Brownish smoke:
Air filter dirty

Main jet too large or fallen out

Starter plunger stuck open

Fuel level too high

Filed Under: Troubleshooting Guides

Motorcycle Maintenance 101 – Basic Clutch Service

November 19, 2007 by Leave a Comment

Trouble with your clutch? It might be time to inspect the condition of your clutch components. Here is a basic guide explaining the steps required. Always review and follow the procedures as explained in your service manual before attempting any clutch service.

Definitions

Pressure Plate – The moving part of the clutch assembly that, working against clutch spring tension, releases the clamping action on the clutch plates when the clutch lever is engaged.

Drive (friction) Plate – Consumable, fiber coated, ring-shaped friction surface that interfaces between the clutch basket tangs and pressure plate. Has tabs sticking out that match the cutouts between the clutch hub tangs and is coated with a friction material that vaguely resembles brake pad compound.

Driven (metal) Plate – Steel or aluminum ring-shaped disks that interface between the clutch hub and the friction plates. Steel plates are most often found in enduro/trail machines and provide longer wear and greater flywheel effect. Aluminum driven plates, near universally found in motocross type machines, are lighter, less durable and provide less flywheel effect. Additionally, aluminum driven plates wear out nearly as quickly as the friction plates themselves, in the process fouling transmission oil at an accelerated pace.

Clutch Springs – Short coil springs that continuously hold the friction and driven plates together through spring tension, preventing slippage except when the clutch lever is engaged. Most often, five or more clutch springs are used per motorcycle clutch assembly. Stiffer or more springs are typical of higher output engines. Softer or fewer springs beget a lighter clutch lever pulling effort.

Clutch Basket – A bowl-shaped gear-driven housing bolted onto the end of the clutch shaft that holds the entire clutch assembly.

Servicing Procedure

Begin by either draining the motor’s transmission oil, or lay bike over on its side, ISDE style (clutch side up). With the bike on its side, the oil doesn’t need to be drained as it pools below the level of the clutch side cover. Next, remove clutch cover (on bikes so equipped) or the entire clutch side engine cover in order to expose the clutch basket. If the entire side cover must be removed, the kickstarter, shifter and/or brake pedal might have to be removed first, depending upon the bike make and model (get a manual). Some models might even require the draining of engine coolant and/or disconnection of power valve linkage. Pray that your scoot has a clutch cover.

With the clutch basket exposed, loosen the five or six fasteners on the face of the pressure plate that compress the clutch springs. In most cases M6-sized fasteners are used, most commonly shod with 10mm hex heads. On occasion you’ll find an 8mm hex head or socket head (KTM) fastener. No matter which, back these bolts out evenly, a little at a time, alternating fasteners back and forth across the clutch basket. If the entire assembly has the tendency spin, drop the bike into gear to prevent this.

With all of these fasteners completely loosened, lift out each bolt, washer and clutch spring and set them aside some place where they’ll stay clean. Measure the free length of the clutch springs and compare that to the to specification for minimum free length listed in your service manual. If the clutch springs have sagged (insufficient minimum free length), they’ll need to be replaced.

With pressure plate retaining fasteners removed, the pressure, friction and driven plates may now be lifted out of the clutch basket. Remove the pressure plate first and set it aside with the clutch springs, someplace where it won’t get dirty. When removing the pressure plate, be careful with the clutch actuation rod. Oftentimes there is a flat needle bearing, spacer, or even a simple ball bearing, that can drop out and become lost. Be sure to pay attention to the order in which these parts go back together. Be advised that for a basic clutch plate replacement, removal of the clutch actuation rod probably isn’t necessary. However, while you’ve got things apart it’s not a bad idea to check the rod for wear or bending, especially if clutch action has been faulty. Just be sure not to lose any of these small parts or forget how they came apart.

Now it’s time to lift out the friction and driven plates. Friction plates sometimes have the tendency to stick together, or even stick to the clutch basket face. A screwdriver or other prying tool can be carefully used to break the slight stiction holding them together. Be careful not to score clutch basket or clutch plate faces and stop immediately if they don’t come readily apart—something must be wrong if that’s the case, and you’ll need to seek higher guidance.

With all of the clutch plates removed, inspect the clutch basket, looking for grooves worn into the basket fingers or scoring on the face. Grooving adversely impacts clutch actuation effort and smoothness. If the clutch basket fingers are grooved more than, say, 1/32nd of an inch or so, they’ll need attention. In extreme cases, the only option is replacing the clutch basket. However, if the grooving is less serious, they can be smoothed out using a hand file. Bear in mind though, this creates more slop in the clutch actuation, so that next time the grooving is likely to be considerably worse. Essentially, its a temporary fix that buys you some additional riding time.

Note that the clutch basket rides on one or two thin needle bearings. If you’re forced to replace the clutch basket, its prudent to change this needle bearing as well. With all that out of the way, we can begin to reassemble things. If you’re just replacing the friction plates, separate out the old friction plates from the driven plates.

To replace the clutch, restack the new plates inside the clutch basket alternating friction plate/driven plate. A friction plate always goes in first, and as such all clutch assemblies always have one more fiber plate than metal plate. Be sure that a fiber plate is the last plate that goes in on the top of the stack as well. Do not stack the plates together dry—coat all of them with transmission oil before you stack them together, or you’ll burn the clutch up the first time you ride the bike.

If your bike is equipped with aluminum driven plates, its highly recommended that they be replaced, or at least checked during the replacement process. Again, your service manual will have a thickness specification for both friction and driven plates. If you’re using your scoot for off-road racing or trail riding, we’d highly recommend you consider replacing aluminum driven plates with aftermarket steel ones. This switch offers three potential benefits to the typical off-road set: Better driven plate longevity (read: forever), less fouling of transmission oil, and greater flywheel effect.

Continue the reassembly process by dropping in the pressure plate. Check your service manual, since some bikes require marks on the pressure plate and clutch basket to be lined up on reassembly. Begin to tighten it down by replacing the clutch springs and their fasteners. Be sure to start these bolts by hand to avoid cross threading them and hosing the clutch hub. Tighten them down evenly, alternating bolts in a cross wise manner. These bolts don’t get torqued very much, so be sure not to manhandle or over-tighten them. There’s a torque spec in your owner’s manual—use it.

Button things up by replacing the clutch cover or side cover, ideally with fresh gaskets. If you drained your oil, be sure to replace it with the proper amount of fresh transmission lubricant. We use Golden Spectro SAE 80w motorcycle gear lubricant in our two stroke gear boxes. In a four-stroke engine, remember to use a 15w40 or better motor oil rather than gear lubricant.

Filed Under: Troubleshooting Guides Tagged With: , ,

Motorcycle Charging System Testing and Troubleshooting Online Manual

November 5, 2007 by 1 Comment

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Our charging system manual unravels the mystery behind your charging system in plain English. You’ll never need to visit a repair shop again and you’ll never have to blindly throw parts at your charging system. This online charging system manual will show you how to pinpoint problems and solve them efficiently.

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Filed Under: Troubleshooting Guides Tagged With: , , , , , , , , , , ,

Four-Stroke Motorcycle Troubleshooting Guide

August 7, 2007 by Leave a Comment

While this is not a complete guide of every possible cause for each problem listed, it will help assist mechanics in troubleshooting some of the most common difficulties they will face. Also check out the spark plug troubleshooting guide from the good folks at NGK.

Engine Doesn’t Start, Starting Difficulty:

Starter motor not rotating:
Starter lockout or neutral switch trouble
Starter motor trouble
Battery voltage low
Relays not contacting or operating
Starter button not contacting
Wiring open or shorted
Ignition switch trouble
Engine stop switch trouble
Main fuse blown

Starter motor rotating but engine doesn’t turn over:
Starter motor clutch trouble

Engine won’t turn over:
Valve seizure
Rocker arm seizure
Cylinder, piston seizure
Crankshaft seizure
Connecting rod small end seizure
Connecting rod big end seizure
Transmission gear or bearing seizure
Camshaft seizure

No fuel flow:
Fuel tap vacuum hose clogged
Fuel tank air vent obstructed
Fuel tap clogged
Fuel line clogged
Float valve clogged

Engine flooded:
Fuel level in carburetor float bowl too high
Float valve worn or stuck open
Starting technique faulty
(When flooded, crank the engine with the throttle fully open to allow more air to reach the engine.)

No spark; spark weak:
Battery voltage low
Spark plug dirty, broken, or maladjusted
Spark plug cap or high tension wiring trouble
Spark plug cap not in good contact
Spark plug incorrect
IC igniter trouble
Neutral, starter lockout, or side stand switch trouble
Pickup coil trouble
Ignition coil trouble
Ignition or engine stop switch shorted
Wiring shorted or open
Main fuse blown

Compression Low:
Spark plug loose
Cylinder head not sufficiently tightened down
No valve clearance
Cylinder, piston worn
Piston ring bad (worn, weak broken, or sticking)
Piston ring/land clearance excessive
Cylinder head gasket damaged
Cylinder head warped
Valve spring broken or weak
Valve not seating properly (valve bent, worn, or carbon accumulation on the seating surface)

Poor Running at Low Speed:

Spark weak:
Battery voltage low
Spark plug dirty, broken, or maladjusted
Spark plug cap or high tension wiring trouble
Spark Plug cap shorted or not in good contact
Spark plug incorrect
IC igniter trouble
Pickup coil trouble
Ignition coil trouble

Fuel/air mixture incorrect:
Pilot screw maladjusted
Pilot jet, or air passage clogged
Air bleed pipe bleed holes clogged
Pilot passage clogged
Air cleaner clogged, poorly sealed, or missing
Starter plunger stuck open
Fuel level in carburetor float bowl too high or too low
Fuel tank air vent obstructed
Carburetor holder loose
Air cleaner duct loose

Compression low:
Spark plug loose
Cylinder head not sufficiently tightened down
No valve clearance
Cylinder, piston worn
Piston ring bad (worn, weak, broken, or sticking)
Piston ring/land clearance excessive
Cylinder head warped
Cylinder head gasket damaged
Valve spring broken or weak
Valve not seating properly (valve bent, worn, or carbon accumulation on the seating surface)

Other:
IC igniter trouble
Carburetors not synchronizing
Vacuum piston doesn’t slide smoothly
Engine oil viscosity too high
Drive train trouble
Brake dragging

Poor Running or No Power at High Speed:

Firing incorrect:
Spark plug dirty, broken, or maladjusted
Spark plug cap shorted or not in good contact
Spark plug incorrect
IC igniter trouble
Pickup coil trouble
Ignition coil trouble

Fuel/air mixture incorrect:
Starter plunger stuck open
Main jet clogged or wrong size
Jet needle or needle jet worn
Air jet clogged
Fuel level in carburetor float bowl too high or too low
Bleed holes of air bleed pipe or needle jet clogged
Air cleaner clogged, poorly sealed, or missing
Air cleaner duct poorly sealed
Water of foreign matter in fuel
Carburetor holder loose
Fuel tank air vent obstructed
Fuel tap clogged
Fuel line clogged

Compression low:
Spark plug loose
Cylinder head not.sufficiently tightened down
No valve clearance
Cylinder, piston worn
Piston ring bad (worn, weak, broken, or sticking)
Piston ring/land clearance excessive
Cylinder head gasket damaged
Cylinder head warped
Valve spring broken or weak
Valve not seating properly (valve bent, worn, or carbon accumulation on the seating surface.)

Knocking:
Carbon built up in combustion chamber
Fuel poor quality or incorrect
Spark plug incorrect
IC igniter trouble

Miscellaneous:
Throttle valve won’t fully open
Vacuum piston doesn’t slide smoothly
Brake dragging
Clutch slipping
Overheating
Engine oil level too high
Engine oil viscosity too high
Drive train trouble

Overheating:

Firing incorrect:
Spark plug dirty, broken, or maladjusted
Spark plug incorrect
IC igniter trouble

Fuel/air mixture incorrect:
Main jet clogged or wrong size
Fuel level in carburetor float bowl too low
Carburetor holder loose
Air cleaner poorly sealed, or missing
Air cleaner duct poorly sealed
Air cleaner clogged

Compression high:
Carbon built up in combustion chamber

Engine load faulty:
Clutch slipping
Engine oiHevel too high
Engine oil viscosity too high
Drive train trouble
Brake dragging

Lubrication inadequate:
Engine oil level too low
Engine oil poor quality or incorrect

Coolant incorrect:
Coolant level too low
Coolant deteriorated

Cooling system component incorrect:
Radiator clogged
Thermostat trouble
Radiator cap trouble
Thermostatic fan switch trouble
Fan relay trouble
Fan motor broken
Fan blade damaged
Water pump not turning
Water pump impeller damaged

Over Cooling:

Cooling system component incorrect:
Thermostatic fan switch trouble
Thermostat trouble

Clutch Operation Faulty:

Clutch slipping:
Friction plate worn or warped
Steel plate worn or warped
Clutch spring broken or weak
Clutch release mechanism trouble
Clutch hub or housing unevenly worn

Clutch not disengaging properly:
Clutch plate warped or too rough
Clutch spring tension uneven
Engine oil deteriorated
Engine oil viscosity too high
Engine oil level too high
Clutch housing frozen on drive shaft
Clutch release mechanism trouble

Gear Shifting Faulty:

Doesn’t go into gear; shift pedal doesn’t return:
Clutch not disengaging
Shift fork bent or seized
Gear stuck on the shaft
Shift return spring weak or broken
Shift return spring pin loose
Pawl spring broken
Shift mechanism arm broken

Jumps out of gear:
Shift fork worn
Gear groove worn
Gear dogs and/or dog holes worn
Shift drum groove worn
Neutral positioning pin spring weak or broken
Shift fork pin worn
Drive shaft, output shaft, and/or gear splines worn

Overshifts:
Neutral positioning pin spring weak or broken
Pawl spring broken

Abnormal Engine Noise:

Knocking:
IC igniter trouble
Carbon built up in combustion chamber
Fuel poor quality or incorrect
Spark plug incorrect

Overheating Piston slap:
Cylinder/piston clearance excessive
Cylinder, piston worn
Connecting rod bent
Piston pin, piston holes worn

Valve noise:
Valve clearance incorrect
Valve spring broken or weak
Camshaft bearing worn

Other noise:
Connecting rod small end clearance excessive
Connecting rod big end clearance excessive
Piston ring worn, broken or stuck
Piston seizure, damage
Cylinder head gasket leaking
Exhaust pipe leaking at cylinder head connection
Cran kshaft runout excessive
Engine mounts loose
Crankshaft bearing worn
Camshaft chain tensioner trouble
Camshaft chain, sprocket, guide worn

Abnormal Drive Train Noise:

Clutch noise:
Weak or damaged damper
Clutch housing/friction plate clearance excessive
Clutch housing gear worn

Transmission noise:
Bearings worn
Transmission gears worn or chipped
Metal chips jammed in gear teeth
Engine oil insufficient

Drive chain noise:
Drive chain adjusted improperly
Chain worn
Rear and/or engine sprocket worn
Chain lubrication insufficient
Rear wheel misaligned

Abnormal Frame Noise:

Front fork noise:
Oil insufficient or too thin
Spring weak or broken

Rear shock absorber noise:
Shock absorber damaged

Disc brake noise:
Pad installed incorrectly
Pad surface glazed
Disc warped
Caliper trouble

Other noise:
Bracket, nut, bolt, etc. not properly mounted or
tightened

Oil Pressure Warning Light Goes On:

Engine oil pump damaged
Engine oil screen clogged
Engine oil level too low
Engine oil viscosity too low
Camshaft bearings worn
Crankshaft bearings worn
Oil pressure switch damaged
Wiring damaged
Relief valve stuck open
O-ring at the oil pipe in the crankcase damaged

Exhaust Smokes Excessively:

White smoke:
Piston oil ring worn
Cylinder worn
Valve oil seal damaged
Valve guide worn
Engine oil level too high

Black smoke:
Air cleaner clogged
Main jet too large or fallen off
Starter plunger stuck open
Fuel level in carburetor float bowl too high

Brown smoke:
Main jet too small
Fuel level in carburetor float bowl too low
Air cleaner duct loose
Air cleaner poorly sealed or missing

Handling and/or Stability Unsatisfactory:

Handlebar hard to turn:
Steering stem locknut too tight
Bearing damaged
Steering bearing lubrication inadequate
Steering stem bent
Tire air pressure too low

Handlebar shakes or excessively vibrates:
Tire worn
Swing arm pivot bearing worn
Rim warped, or not balanced
Wheel bearing worn
Handlebar mounting bolts loose
Steering stem head bolt loose

Handlebar pulls to one side:
Frame bent
Wheel misalignment
Swing arm bent or twisted
Steering maladjusted
Front fork bent
Right/left fork legs oil level unbalanced

Shock absorption unsatisfactory:
(Too hard)
Front fork oil excessive
Front fork oil viscosity too high
Tire air pressure too high
Front fork bent

(Too soft)
Front fork oil insufficient and/or leaking
Front fork oil viscosity too low
Front fork, rear shock absorber spring weak
Rear shock absorber oil leaking

Brake Doesn’t Hold:

Air in the brake line
Pad or disc worn
Brake fluid leak
Disc warped
Contaminated pad
Brake fluid deteriorated
Primary or secondary cup damaged
Master cylinder scratched inside

Battery Discharged:

Battery faulty (e.g., plates sulphated, shorted through sedimentation, electrolyte level too low)
Battery leads making poor contact
Load excessive (e.g., bulb of excessive wattage)
Ignition switch trouble
Alternator trouble
Wiring faulty
Regulator/Rectifier trouble

Battery Overcharged:

Regulator/Rectifier trouble

Filed Under: Troubleshooting Guides