BUBF Trouble Shooting Guide

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The objective of this trouble shooting guide is to help you get your bike running if it fails away from assistance.  This is a short guide listing things to try/check to get you to your next stop and service/help.  Some of the suggestions require a copy of the bike's wiring diagram and a multi-meter (DC volts and ohms).  I'd be glad to get you a 1996 BUBF wiring diagram.  Just request one through the VROC news group.  And a basic, low cost DC volts and ohm multimeter can be purchased for around $10.00 at companies like Harbor Freight.  This TSG, the wiring diagram, and a small multi-meter will easily fit in one corner of a tank or saddle bag.  

 

BLUE text in this BUBF Troubleshooting Guide expands on a topic or is a link to more information.

Underlined text is usually a link top more information

 

 Engine Doesn't Start, Starting Difficulty

 

Starter motor not rotating

Battery voltage low (always make sure that the POSitive and NEGative terminal connections are clean and tight)

If you hear a "clicking sound" when you press the starter switch, this usually indicates the battery voltage to the relay is low (less than 12.0 VDC on a voltmeter).  Low voltage can close the relay switch, but without enough voltage to keep the relay switch closed, the relay latch creates a clicking sound as it cycles between closed and open .

 

If you don't hear the relay clicking, but the headlight, running lights, and tail light are dimly lit, it's likely the battery voltage has been drawn very low because the battery cannot take a charge, a charge cannot get to the battery due to a poor connection, or the charging system is not working correctly.  

Also, if the lights come on when you turn the ignition on, and then go out when you press the starter switch without the engine turning over, it's very likely the battery has a shorted cell.  If possible, re-charge the battery to 12.6VDC and then try starting the bike.  If the same problem occurs, have the battery load tested to eliminate a shorted battery cell.

 

If the only problem is a uncharged battery and the battery is otherwise OK, a BUBF can be push started.  If you don't have a long downhill run, you'll need at least one person to push while you operate the bike.  Put the bike in neutral.  Adjust the carb enricher just as you normally would to start you bike.  Turn ON the ignition.  Get the bike moving as fast as possible.  With the bike in motion you will be able to override the shifter lock out and shift the transmission into second.  If you are being pushed, signal you are in second and slowly release the clutch (you can start the bike in 1st gear, but the abrupt low torque kick-back can be a surprise to you and make it harder to push the bike).  The bike's momentum and continued pushing should get the engine running as long as the problem is directly related to the battery not holding a charge.  Keep the rpms high enough to spin the stator fast enough to generate sufficient current to keep the bike running. 

Starter lockout or neutral switch trouble (CLICK here for a primer on these switches including testing)

The starter lockout switch is located in front of the clutch lever and is connected to the lever assembly by a three-wire clip-locked (brown) electrical connector.  The starter lock-out switch can become loose.  If loose, disconnect, clean and reconnect.  

The neutral switch (located on the left side of the engine behind the left side engine cover on the lower portion of the front bevel gear case) is a sealed switch.  The exterior should be clean, the wire connection clean and tight, and the wire in tact.  

Starter motor trouble

Check that the starter cable is clean and properly connected.  The starter motor grounds directly to the engine block.  Check that the contact area is clean.  A work around a bad starter motor is to push start your bike. 

 Relays not contacting or not operating

There are two (2) starter circuit relays.  One is located at the top-right-rear of the battery (near the red plastic cover),  The other is in the Junction Box (fuse box).  You will need either a 12 volt test light or volt meter to test either relay (with the one on the battery the easiest to get to).  You want to test the wire that triggers/sets the relay latch.

 Starter button not contacting  Check, clean, and test.  If the button fails testing, replace immediately.

 Wiring open or shorted

  Ignition switch trouble

There are several wires attached to the ignition switch.  Check that the solder points are all in tact.  Check continuity of the circuits entering and leaving the ignition switch.  You will need a wiring diagram.

  Engine stop switch trouble  Check, clean, and test with multimeter ohm tester.

  Fuse blown

There are two (2) starter related fuses to check.  One fuse is in the Junction (fuse) Box under the rider seat.  The other fuse is a 30 amp fuse located under the riders seat next to the starter relay at the upper right rear of the battery.

Starter motor rotating but engine doesn't turn over

Starter motor clutch trouble

This problem is beyond the scope of this trouble shooting guide and needs to be addressed by a qualified mechanic)

Engine won't turnover

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

Balancer bearing seizure (All nine (9) of the seizure problems listed above are beyond the scope of this trouble shooting guide/ and need to be addressed by a qualified mechanic)

No fuel Flow:  

 Fuel tank air vent obstructed (or pinched closed)

 Fuel tap clogged

 Fuel line clogged (or pinched closed)

 Float valve clogged

 Fuel pump trouble

Test by carefully opening each carb bowl's Allen drain screw to make sure that there is fuel in each carburetor bowl.  If there is no fuel in the bowls, the fuel pump mechanism may be stuck.  Tap the fuel pump gently with a screw driver handle a few times to see if this frees up the pump mechanism.

Engine flooded:

Starting technique faulty

Engine cold -pull out the enricher knob and press start switch without twisting throttle.

Engine warmed up or hot - press start switch and twist throttle a bit if engine does not catch/start quickly.

When flooded, crank engine with  the throttle fully open to allow more air to reach the engine)

Fuel level in carburetor float bowl too high (link check float level)

Float valve worn or stuck open

No spark; spark weak: (link to BUBF battery testing)

Battery voltage low (Click to see comments in Starter motor not rotating above)  

A low voltage battery can turn the starter motor, but not have enough current to simultaneously create a strong spark to start the engine.

Spark plug dirty, broken, or maladjusted

Spark plug cap or high tension wiring trouble

Spark plug cap not in good contact

Spark plug incorrect #7 NGK spark plugs consistently perform best in a BUBF.

IC igniter trouble  Remove IC igniter and bench test, if possible.  Procedure in service manual.

Neutral, starter lockout, or side stand switch trouble (CLICK here for info on checking and testing these switches)

Pickup coil trouble

Ignition coil trouble

Test the spark quality with extra spark plug inserted in the spark plug cap and held against engine.

Ignition or engine stop switch shorted  Checking and testing either switch requires a multi-meter and wiring diagram.

Wiring open or shorted

Fuse Blown Check fuses in junction box under rider seat.  Decal on inside of JB cover identifies fuse application.

Compression Low:

Spark plug loose.  Check and torque to spec (12.5 ft-lbs or equivalent 150 inch-lbs.

 

(The ten (10) problems listed below in this section are major repairs that typically require engine removal and are beyond the scope of this trouble shooting guide)

Cylinder head not sufficiently tightened down. 

Cylinder, piston worn

Piston ring bad (worn, weak or broken, or sticking)

Piston ring/groove clearance excessive

Cylinder head gasket damage

Cylinder head warped

Valve spring broken or weak

Valve not seating properly (valve bent, worn, or carbon accumulation on the seating surface)

Hydraulic lash adjuster damaged (worn, seizure, or spring broken)

Hydraulic lash adjuster oil passage clogged

 

 

Poor Running at Low Speed:

 

Spark Weak

Battery voltage low (Click to see comments in Starter motor not rotating above)

Spark plug dirty, broken, or maladjusted Clean, replace, or re-gap.

Spark plug cap or high tension wiring trouble

Spark plug cap not in good contact 

Spark plug incorrect  #7 NGK spark plugs consistently perform best in a BUBF.

IC igniter trouble Remove from bike and bench test as directed by KAW service manual.

Pickup coil trouble Check per KAW service manual procedure

Ignition coil trouble  Test the spark with extra spark plug in spark plug wire held against running engine.

Fuel/air mixture incorrect

Pilot screw maladjusted

Pilot jet, or air passage clogged

Needle jet (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 or surge tank duct loose

Fuel pump trouble

Backfiring when deceleration

Vacuum switch valve broken

Air suction valve trouble

Idle air-fuel mixture too lean.  Turn out pilot screws 1/2 turn or more to richen mix.  Test ride bike after each turn out.

Other:

IC igniter trouble  Remove from bike and bench test as directed by KAW service manual.

Carburetors not synchronizing  Check sync with manometer or pair of pressure gauges.

Carburetor vacuum piston doesn't slide smoothly

Engine oil viscosity too high

Drive train trouble

Final gear case oil viscosity too high  Drain and add proper viscosity/type per user manual

Brake dragging

Air suction valve trouble

Vacuum switch valve trouble

Side (kick) stand switch

A faulty switch can intermittently ground out the igniter circuit stopping the engine even if the side stand is up.  Test and replace.

       Contaminated fuel  

Drain tank and refill with known good and clean fuel.  Pour a half bottle of “Dry gas” into full tank to remove water contaminates. Add a ½ bottle of Berrymans B-12 Liquid Carb cleaner to a full tank of gas to clean the jets and fuel passages.

 

 

Poor Running or No Power at High Speed: (good link for generally trouble shooting poor performance http://jr_allas.tripod.com/documents/running_poorly.htm)

 

Firing incorrect:

Spark Plug Dirty  Remove and clean with wire brush and re-gap.

Spark plug cap shorted or not in good contact Do ohm check.  If greater than 5k ohms (or infinite) reading, replace

Spark plug incorrect  #7 NGK best for BUBF's.

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 clogged

Air cleaner clogged, poorly seated, or missing

Air cleaner or surge tank duct poorly seated

Water or foreign matter in fuel

 Fuel tap clogged

Fuel line clogged

Fuel pump trouble

Knocking

Carbon built up in combustion chamber  Use Seafoam or other carbon removal product added to fuel tank.

Fuel poor quality or incorrect  Drain tank and fill with known clean fuel.  87 octane best for BUBF's.

Spark plug incorrect  #7 NGK best all around spark plug to use, or just to test with.

IC igniter trouble  Remove from bike and bench test as directed by KAW service manual.

Backfiring when deceleration:

Vacuum switch valve broken

Air suction valve trouble

Miscellaneous

Throttle valve won't fully open  Butterfly valve on carb obstructed or broken

Carburetor vacuum piston doesn't slide smoothly.  Clean and check operation

Brake dragging.  Check piston travel.  It should retract 1-2 MM when brake lever released.

Clutch slipping.  Most obvious at highway speed by accelerating.  IF engine rpms increase but bike "lags" behind, check clutch spring and other components

Overheating.  Wrong fuel mix, spark plugs, fuel, etc.

Engine oil level too high.  Check with bike in upright position.  Drain if oil covers sight glass before or at upright position.

Engine oil viscosity too high.  Use oil as recommended in your user manual (usually 20W50 SF).

Air suction valve trouble  Failure or clogging of valve located on front/back side of cylinders.

Vacuum switch valve trouble Inline with air su7ction valve.  Can be disconnected, clogged, broken.

Balancer mechanism malfunctioning  Internal engine component.  Take bike to qualified wrench.  Beyond this trouble shooting guide

 

ADDITIONAL TOPICS AND  INFORMATION BELOW IS IN THE PROCESS OF BEING ADDED TO THIS TROUBLESHOOTING GUIDE ///////////////////////////////////

IV.              Battery does not charge

c.      With battery fully recharged, start bike and check for 13.5 to 15.0 volts at the battery terminals with a voltmeter at ~¼ throttle (about 1500 -1800 rpms).

                                                               i.      If charging voltage is less than 13.5 volts, bench test regulator/rectifier.  If reg/rec bad, replace.

                                                             ii.      If regulator/rectifier tests OK, check stator.   If stator tests bad, replace.

d.      Check and clean all wire connections from stator to reg/rec to starter button.  Remove dirt and corrosion, tighten loose connections, and repair burned or broken wires.  Apply electrical dielectric grease to all connections.

V.                 Headlight will not go on Check fuse and all wiring connections

VI.              Oil leaks Near bottom-left of engine Can be a worn shifter shaft seal.  Near top of engine can be worn/loose rocker case gasket (s)

VII.            Burning Oil Bad/worn cylinder rings

VIII.         Transmission

IX.       Clutch. Slip.  Spring worn; oil additives effecting plates

X.                 Tires Cupping can be casusd by bad or worn wheel bearings, and/or steering head bearings worn.

XI.              Handlebars  Excessive vibration can be caused by worn tire or worn steering head bearings.

XII.            Shifting.  Hard shifting can be caused by worn or bent shifter forks.  At high rpms, transmission can slip out of second into neutral.

XIII.          Ear Shave Running Poorly

1.  Hoses (6) reconnected incorrectly 

2. Vacuum ports not capped

3.  K&N or UniFlow air filters not seated correctly on carburetors

4.  Carburetors not seated and tight to intake manifolds

5.  140 main jets, and pilot jets (replace with #48's - 1 1/2, turns out,  or #45's - 2 1/2, turns out) not seated correctly, loose, or have fallen out.  NOTE: Stock pilot jets (#42's more than 4 full turns out) can cause poor running and engine stumbling at idle and low speeds)

6.  If diaphragms removed (carb tops opened), be sure it is seated correctly, and needle and spring installed correctly

7.  Exhaust fresh air intakes not marbled or coasters not tight or improperly sealed.

 

IX.  Electrical running lights, wiring.