Electrical

When testing continuity of a circuit, always make sure that the circuit has been isolated from any form of electricity. POSSIBLE IRREPARABLE DAMAGE TO YOUR METER MAY OCCUR if you do not follow this advice.

Specifications

IGNITION/CHARGING SYSTEM
Spark Plug Type NGK BP7HS
Spark Plug Gap 0.024-0.028 in.
Spark Plug Cap Resistance 4.5k-6k ohms
Ignition Coil Resistance primary secondary 0.5-1.0 ohm orange to ground 4500-7000 ohms high tension – plug cap removed – to ground
Trigger Coil peak voltage resistance 2.4-3.6V (white/red to black) 93.6-140.4 ohms (white/red to black)
Source Coil peak voltage resistance 148-222v (black/red to black) 442.6-668.4 ohms (black/red to black)
CDI/Ignition Coil peak voltage 129.6-194.4V (orange to black)
AC Output peak voltage resistance peak voltage resistance 6.2-9.2V yellow/red to black 0.5-0.7 ohm yellow/red to black 7.4-11.2V white to black 0.5-0.7 ohm white to black
Choke Circuit peak voltage 5.9-8.9V yellow/red to black

Trouble Shooting

No or little Electrical output Battery is discharged Charge or replace battery
Loose or broken connection Tighten or repair wire
Fuse is blown Replace fuse
Regulator rectifier bad Replace regulator rectifier
Stator is bad Replace stator
Starter will not turn Battery is dead Charge battery
Tether has been pulled out Replace tether
Brake lever is not pulled in Pull lever
Brake lever is pulled Brake safety switch needs to be checked/replaced
Ignition switch is on still will not start Check switch for continuity replace if bad
Ignition switch tested good still will not start Check the push button starter switch for current.
Fuse is bad Replace
Starter is bad Check and repair or replace
Starter relay Check and repair or replace
Starter turns, unit still will not start. Choke

Testing Electrical Components

All of the electrical tests should be made using a good quality multi-meter. Please note that many factors can change the readings of a meter; temperature, the condition of the meter leads, the condition of the batteries in the meter are just a few items that can change the readings. When troubleshooting a specific component, always verify that the fuse is good, that the bulb is good, that the connections are clean and tight, that the battery is fully charged, and that all appropriate switches are activated.

Testing the Trigger Coil

Disconnect the triple-plug connector on the left side of the engine.

Voltage

  1. Set the meter to the A.C. Voltage position.
  2. Connect the red tester lead to the white/red wire; then connect the black tester lead to the black wire.
  3. Crank the engine over using the electric starter. The meter should read 2.4-3.6 volts.

Resistance

  1. Set the meter to the OHMS position.
  2. Connect the red tester lead to the white/red wire; then connect the black tester lead to the black wire.
  3. The meter should read 93.6-140.4 ohms.

Testing the Source Coil

Disconnect the triple-plug connector on the left side of the engine.

Voltage

  1. Set the meter selector to the A.C. Voltage position.
  2. Connect the red tester lead to the black/red wire; then connect the black tester lead to the black wire.
  3. Crank the engine over using the electric starter. The meter should read 14.8-22.2 volts.

Resistance

  1. Set the meter selector to the OHMS position.
  2. Connect the red tester lead to the black/red wire; then connect the black tester lead to the black wire.
  3. The meter should read 442.6-668.4 ohms.

Testing the C.D.I, and Ignition Coil

Disconnect the wires at the coil

Voltage

  1. Set the meter selector to the D.C. Voltage position.
  2. Connect the red tester lead to the orange wire; then connect the black tester lead to the black wire.
  3. Crank the engine over using the electric starter. The meter should read 129.6-194.4 volts.

AC Output

Disconnect the triple-plug connector on the left side of wire the engine.

Voltage

  1. Set the meter selector to the A.C. Voltage position.
  2. Connect the red tester lead to the yellow/red wire; then connect the black tester lead to the black
  3. Crank the engine over using the electric starter. The meter should read 6.2-9.2 volts.

Resistance

  1. Set the meter selector to the OHMS position.
  2. Connect the red tester lead to the yellow/red wire; then connect the black tester lead to the black wire.
  3. The meter should read 0.5-0.7 ohm.

Voltage

  1. Set the meter selector to the D.C. Voltage position.
  2. Connect the red tester lead to the white wire; then connect the black tester lead to the black wire.
  3. Crank the engine over using the electric starter. The meter should read 7.4-11.2 volts.

Resistance

  1. Set the meter selector to the OHMS position.
  2. Connect the red tester lead to the white wire; then connect the black tester lead to the black wire.
  3. The meter should read 0.5-0.7 ohm.

Magneto Assembly

Removing the Magneto Assembly

  1. Disconnect the battery
  2. Remove the flywheel from the engine. Always use the proper puller for the job. CAUTION: do not use a hammer to remove the flywheel; the crankshaft and other internal components will be damaged!
  3. Remove the stator and timing sensor from the stator plate.

Installing the Magneto Assembly

  1. Install the timing sensor and stator onto the stator plate. Apply red Loctite #271 to the Phillips-head cap screws. Tighten securely.
  2. Install the flywheel. Torque the flywheel nut to 20 foot pounds Choke Circuit

Choke Circuit

Disconnect the black double-plug connector on the left side on the engine.

Voltage

  1. Set the meter selector to the D.C. Voltage position.
  2. Connect the red tester lead to the yellow/red wire; then connect the black tester lead to the black wire.
  3. Crank the engine over using the electric starter. The meter should read 5.9-8.9 volts.

Battery

Safety Note: Battery electrolyte contains sulfuric acid, which can cause severe burns. Avoid contact with skin, eyes, or clothing. If you come into contact with sulfuric acid, flush the area with water and if needed seek medical attention. Proper maintenance of a battery will help ensure the battery will last its rated lifetime. Keeping the battery fully charged, especially during extended periods of non use will help the battery last longer (charge every 30 days). Clean and tight terminals will also help its longevity. Before installing a new battery, fill it with electrolyte and let stand for 20 minutes before installing the caps, and then charge the battery following the battery manufactures instructions. Do not use quick charge unless it is urgent. The battery needs to be taken out of the vehicle while charging. Do not unplug electrical components from the wire harness while the ATV is running. This could cause a spark or a voltage spike and damage other components such as the bridge rectifier, ignition module, light bulbs…etc. Turn the main switch to OFF before the beginning any repair. When checking the Voltage, Ohms, or Amps, use the proper electrical meter, preferably a multi-meter. Make sure to be familiar with proper use of your meter; performing an amp draw test while the meter leads are hooked up wrong can result in damage to your meter and the electrical system.

CHARGING: The battery manufacturers charging instructions take precedence and need to be followed before following through with this procedure.

  1. Remove the battery from the ATV. Remove the negative cable first; then remove the positive cable. Do not charge the battery while it is in the ATV and the cables connected
  2. Trickle-charge the battery at 1.4 amps for 8-10 hours.
  3. Place the battery into position in the ATV and secure.
  4. Connect cables to the proper terminals: positive cable to the positive terminal (+) and negative cable to the negative terminal (-). Connect the negative cable last.

Testing Voltage

  1. Remove the seat; then disconnect the negative and positive battery terminals.
  2. Connect the red tester lead to the positive battery, the black lead to the negative post.
  3. The meter must show 12.8 volts or more.
  4. Reconnect the positive and negative terminals.

Brake Light Switch

The switch connector is the two individual single connectors located under the left-front fender.

NOTE: The ignition switch must be in the ON position. Voltage

Wiring Harness Connector

  1. Set the meter selector to the D.C. Voltage position; then turn the ignition switch to the ON position.
  2. Connect the red tester lead to the green/white wire; then connect the black tester lead to ground.
  3. The meter should show battery voltage. If battery voltage is not present, troubleshoot the battery, fuse, switch, or the main wiring harness. If the meter shows battery voltage, the main wiring harness is good; test the switch and other components of the switch, the connector, and the switch wiring harness for resistance.

Resistance, Brake Light Switch Connector

NOTE: The brake lever must be compressed for this test. Also, the ignition switch must be in the OFF position.

  1. Set the meter selector to the OHMS position.
  2. Connect the red tester lead to the black wire; then connect the black tester lead to the green/yellow wire.
  3. When the lever is compressed, the meter should read less than 1 ohm.
    NOTE: If the meter shows more than 1 ohm of resistance, troubleshoot or replace the switch/component, the connector, or the switch.

Fuse

  1. Set the meter selector to the OHMS position.
  2. Connect the red tester lead to one spade end of the fuse; then connect the black tester lead to the other spade end.
  3. The meter should read less than 1 ohm resistance. If the meter reads open, replace the fuse. Make sure to use the proper size fuse when replacing.

Ignition Coil

The ignition coil is attached to the upper frame behind the left-side of the front fender panel. The coil can be accessed inside the front-left fender well. Primary Winding Resistance

  1. Disconnect the orange wire from the coil.
  2. Connect the red tester lead to the orange wire (with the wire removed); then connect the black tester lead to ground.
  3. The meter should read 0.5-1.0 ohm.

NOTE: If the meter does not show as specified, replace ignition coil. Secondary Winding Resistance

  1. Connect the red tester lead to the high tension lead (plug cap removed); then connect the black tester lead to ground.
    NOTE: if you do not remove the spark plug cap, your readings will be off.
  2. The meter should read 4500-7000 ohms.
    NOTE: If the meter does not show as specified, replace ignition coil.

Spark Plug Cap Resistance

  1. Connect the red tester lead to one end of the cap; then connect the black tester lead to the other end of the cap.
  2. The meter should read 4.5k-6k ohms.
    NOTE: If the meter does not show as specified, replace the spark plug cap.

Ignition Switch

The connector is accessible below the front fender panel in the front-right fender well Voltage

  1. Set the meter selector to the D.C. Voltage position.
  2. Connect the red meter lead to the red wire; then connect the black meter lead to ground.
  3. Meter must show battery voltage.

NOTE: If the meter shows no battery voltage, troubleshoot the battery or the main wiring harness. Resistance

NOTE: Perform this test on the lower side of the connector. Always disconnect the battery when performing resistance tests to avoid damaging the multimeter

NOTE: Perform this test on the upper side of the connector.

  1. Turn the ignition switch to the ON position
  2. Set the meter selector to the OHMS position.
  3. Connect the red tester lead to the red wire; then connect the black tester lead to the orange wire.
  4. The meter should read less than 1 ohm.
  5. Connect the red tester lead to the red wire; then connect the black tester lead to the gray wire.
  6. The meter should read less than 1 ohm.
  7. With the switch in the OFF position, connect the red tester lead to the red wire and the black tester lead to each of the remaining wires (orange and gray). The meter must show an open circuit on both wires.
    NOTE: If the meter shows more than 1 ohm of resistance, troubleshoot or replace the switch/component, the connector, or the switch wiring harness.

Handlebar Control Switches

The connector is the red one in front of the steering post. The connector is accessible in the front-left fender well.

NOTE: These tests should be made on the top side of the connector.

Starter Button Resistance

  1. Set the meter selector to the Diode position
    NOTE: if your meter does not have a diode tester you can use the standard ohm setting but you must pay attention to which end you have the positive tester lead hooked to. If you do not get the desired reading change the leads around.
  2. Connect the red tester lead to the orange/white wire; then connect the black tester lead to the yellow/green wire.
  3. With the starter button depressed, the meter should read 0.5-0.7 ohm.
  4. With the starter button released, the meter must show an open circuit.
  5. Connect the red tester lead to the yellow/green wire; then connect the black tester lead to the orange/white wire
  6. With the starter button depressed, the meter must show an open circuit.
    NOTE: If the meter does not show as specified, replace the switch/component, connector, or switch harness.

Operator Presence Switch Resistance

  1. Set the meter selector to the OHMS position.
  2. Connect the red tester lead to the orange wire; then connect the black tester lead to the orange/white.
  3. With the switch in the OFF position, the meter must show an open circuit.
  4. With the switch in the RUN position, the meter must show less than 1 ohm.
    NOTE: If the meter shows more than 1 ohm of resistance, troubleshoot or replace the switch/component, the connector, or the switch wiring harness.

Starter Motor

Removing and Disassembly

  1. Disconnect the battery.
    *** Always disconnect the negative battery cable from the battery first; then disconnect the positive cable.
  2. Remove the starter motor from the engine.
  3. Remove the nut securing the positive cable to the starter; then remove the cable from the starter. Account for the o-ring that goes on the end of the starter.
  4. Remove the two cap screws securing the main housing to the end housing; then remove the main housing. Account for two washers that go onto the bolts and the o-ring that goes between the main housing and the end cap.
  5. Remove the two brushes and armature from the end housing.

Inspection

  1. Check the armature windings for damage.
  2. Check the brushes for wear. NOTE if the starter needs to be serviced, unless it is minor like the brushes, replace the starter as an assembly

Assembling and Installing

  1. Install the armature and brushes into the end housing.
  2. Install the o-ring and main housing over the end housing and secure with two cap screws coated with red Loctite #271. Tighten the cap screws securely.
  3. Install the starter motor

Voltage Regulator Rectifier

The regulator is located near the battery. Its function is to change AC current to DC current then reduces the voltage from 28 volts AC (or higher) to 12.8 to 13.5 volts DC.

  1. Set the meter selector to the DC Voltage position.
  2. Test between the black and white wires.
  3. With the engine running at a constant 5000 RPM, the meter should read 12-14 volts.

If the voltage is too low or too high, replace the regulator.

Ignition Timing

The ignition timing cannot be adjusted; however, items like the flywheel key, flywheel, and stator can affect the timing of the engine.

2 Responses

  1. Dave Skidmore
    Dave Skidmore at |

    Yamaha Jog R 50cc 2003 problem with indicators when engine is ticking over normally indicators flash when throttle is pulled back the power in indicators drop until no indicators flashing (no indicator light on high revs) but the headlamps go righter. I have changed the starter relay and also changed the regulator but this has not resolved the problem. The starting motor does not work. Can anyone give me a solution to this problem.

  2. don lamprey
    don lamprey at |

    hi , when first buy this used adly moped it had no head light working . no bulb in it .
    every thing else work fine . latly i hear a pop noise i keep thinking it my tired blown but that not the case . ijust drive today and use blinkers and a sound like horntring to wokrbut no good then a loud bang up front happen .
    i had bought a bulb for it headlight one and noticed a drop in light then when drive or rpm up it get bright. the bulb last a day and blew .
    is this possable voltage regulator ? is that what you call the voltage rectifier . or is that two things ? i am feeling i am blowing something every time i use something . i now cant start moped with starter or use blinkers. tail out blown head light blown horn no good . it still runs when i kick start it though and does seem to not be slugish . any advice be helpful so as to buy what i need to fix problem .
    i will use what trouble shooting you have on this web site but i dont have any tester . ill just look with eyes and check fuse and the area where i heard a loud bang or pop niose from up front left side of moped about where head light assmby is . i may very well have to replace many items once i fix this problem . how ever it important for me to know this before buying any electronic parts that may very well just blow again .
    my feelings tell me it was puttin gout too much volts to things and now is blowing every thing . even dash board lights when iuse switches like to high beeam and low beam and the backgorund dash lights are not working . gas gauge does not read by just turning key but when i kick start it and drive it the gauge slowly shows how much gas i have in it .
    scooter all i have to get around . should i just buy another or is it better to fix ? i pay 300 for it . it been good to me .
    yours truly don lamprey adly silver fox 50

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Contacts

Store Address:
AJ USA, Inc. 129 Bethea Rd
Suite 405

Fayetteville, GA 30214

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Phones:
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