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No Spark Troubleshooting 1984 Honda BIG RED 200ES

December 23, 2017

I recently worked on a 1984 Honda BIG RED 200ES that had no spark when I bought it. I wrote up this article to give an idea how I troubleshot and resolved this issue. I tried to provide a complete start to finish on this subject so it can be used as a resource to help troubleshoot and resolve a no spark condition on a 1984 200ES BIG RED.

 

I typically have a particular troubleshooting process I follow testing and evaluating components step by step. This has worked well in the past but in this case it is not always straight forward of pass/fail. That’s ok I like a challenge and increasing my experience so it will be easier to diagnose the next time.

 

Very basic CDI Ignition theory: In my experience knowing how the system is designed to work is a great help when troubleshooting. It lets you follow the process to know at what point the system is breaking down. The problem here is no spark but getting spark at the spark plug takes a series of events and there is some safety built in (kill switch) which can interrupt the system.

Ok the theory. Again I am going to keep this basic. The BIG REDS use an AC CDI system. This means that a battery is not required to generate a spark.

  • As the flywheel spins the alternator (mounted under the flywheel and does not spin) creates current.

  • The current is sent by a wire to the CDI box (Black box mounted on frame under gas tank). The CDI box stores the current until the spark is needed

  • The pulse generator (mounted in the rocker cover under the cover marked “CDI”) tells the CDI box when the spark is needed. It has a magnet on a rotor. The rotor is driven by the timing chain which is connected to the crankshaft/flywheel. So when the magnet on the rotor passes the stationary portion of the pulse generator it triggers the CDI box to discharges its stored current into the ignition coil.

  •  The ignition coil (mounted on frame under gas tank and has the lead to the spark plug connected to it) amplifies the current and puts it through the spark plug wire and into the spark plug creating a spark.

  • This cycle repeats itself as the engine rotates.

 

 

 

 

Background:  I bought this 1984 BIG RED 200ES used and not running. The person I bought this from told me that the motor lost spark and has been sitting for a while. I found two CDI boxes in the rear storage area of the ATC so I know somebody probably already attempted to troubleshoot this.

 

Troubleshooting: Before I start I get a few things ready. I pulled out the service manual, a digital multimeter, and a known good working spark plug. The service manual is important for the troubleshooting guide, wiring diagram, and the specs for testing some of the components. Next I make sure I have access to the components. In this case I removed the gas tank, recoil, timing inspection plug, pulse generator cover, and exposed the wiring in the headlight housing.

 

Here is the process I followed on this one after I verified that I had no spark at the spark plug:

  • I will do a quick overview to check the condition of the wiring and connections. I will also look for loose wires that are not connected. I will fix any wiring problems before I move on.

 

  • Check ignition (key) switch: Disconnected the red and yellow/red wires coming out of the ignition switch. Connected the multimeter and checked to see if I had continuity in the on position. Then checked for an open circuit in the off position. This checked out ok so I reconnected the wires and on to the next check.

 

  • Engine stop switch: This is the one located on the left side of the handlebar. Checked to see if I had continuity between the black and green wires coming from the switch with the switch in the “off” position. Checked for an open circuit in the “run” position. Switch checked out ok so I reconnected the wires and moved on.

 

  • Neutral/Reverse switches: The 1984 BIG RED was designed so that it cannot be started (electric start will not operate and no spark from ignition) unless the transmission is in neutral.

 

 

  • Alternator: This is located on the lower left side of the motor behind the recoil start. There is a black/red wire coming out of the engine case along with two yellow wires. With the multimeter set to resistance (ohms) Put the red test lead on the red/black wire and the black test on an electrical ground. The resistance should be 100 to 400 ohms according to the service manual. The resistance values were good so I moved on to the next test. Keeping the test leads connected switch the multimeter to read AC voltage. Use the electric start to turn the motor over and check the voltage. It should be at least 10 Volts AC. I take the spark plug out of the motor to allow the motor to crank over easier. Alternator tested out ok so moving on.

 

  • CDI box:  I will disconnect the CDI box and check the resistance per the service manual. This has been debated whether this is a “good” test method. I don’t know if it is or isn’t but I don’t have another method. It is always good to have a known working spare. The resistance values checked out so I am moving on.

 

 

 

 

 

  • Pulse generator:  For this I do a visual of the assembly and check that the advance assembly is working by manually turning it. Next I checked the rotor surface and the pulse generator surfaces. They needed to be cleaned and looked a little beat up (rotor and pulse generator surfaces). The wiring for the pickup where it entered the box looked a little frayed. I rotated the motor to the “F” mark on the flywheel to line up the rotor and pickup and checked the gap with some feeler gauges. The air gap should be .015” to .025”. The air gap was close to the max range of .025”. Next I checked the continuity of the pulse generator. I disconnected the two wires and hooked one test lead to the blue and yellow wire and the other to the green wire coming from the pulse generator. Continuity was good and resistance was about 27 ohms so I left the test leads on and switched the multimeter to read AC voltage. Use the electric start to turn the motor over and check the voltage. I read like .7 volts AC and so I moved on.