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BurmashaveAt some time, you will want to get acquainted with a multimeter (MM) if you are restoring an SOHC/4 (or working on any vehicle for that matter). This FAQ should give you a basic introduction to purchasing and using a multimeter.
What Is a Multimeter?If you're not quite sure what a multimeter is, Wikipedia has an entry for Multimeter explaining what
Multimeters do and what features they offer.
Selecting a MultimeterYou can find a good multimeter for under $20. Multimeters come in two varieties -- analog or digital. Most MM's are digital, and most users find digital MM's easier to use, although analog meters are entirely sufficient for our purposes. You can find multimeters in electronics shops or home improvement stores. One feature provided by more expensive models is the ability to test amperage in ranges beyond milliamps. A multimeter with a higher amperage range can be useful; however, testing on an SOHC/4 can be done without this feature.
How Do I Use a MultimeterThere are some good (very brief) tutorials on the web:
Electronics ClubThe helpful folks at the Electronics Club provide a clear guide to using either a digital or analog MM for basic measurements.
U of Michigan Interactive Guide to MM UseCheck this out: it's an interactive MM demo! The U of Michigan has an interactive Flash application that teaches you how to use a multimeter by allowing you to connect leads and perform tests. It's a fun way to get acquainted with a multimeter without leaving your chair.
Basic Electrical Theory for Boaters: Multimeter - The Invaluable ToolBoatSafe.com has a very good guide that includes hands-on examples and pictures for testing voltage, amperage and resistance. The BoatSafe guide meshes with their
Electricity 101 for Boaters, which is a brief introduction to electrical theory.
What Are Volts, Amps., etc?For those so inclined, there are also a few guides that quickly explain the theory behind the measurements. A brief understanding of electrical concepts often helps when troubleshooting components more complex than a bulb or switch.
Electricity 101 for BoatersAs mentioned above, BoatSafe.com has a brief guide to electrical theory. Their guide uses the Hydraulic Analogy that is often made between basic electrical principles and the movement of water through pipes.
4HV.org: Basic Electrical Theory4HV.org has a very clear and concise guide to electrical theory.
How Should I Troubleshoot? (see also Jonesy's Wiring Guide and Bodi's Electrical Fault Finding in this FAQ)Troubleshooting electronics may seem like voodoo at first; however, it is something that can be learned the same way mechanical troubleshooting is picked up. I am by no means an electronics expert; however, here are some tips that may be useful:
1) Be patient and as methodical as possible.
Note TwoTired's technique for troubleshooting a set of coils. Flailing will not likely save you time, nor will it provide good information if you ultimately need to post a question.
2) Check the FAQ and search the archives for specific troubleshooting procedures. Important circuits, such as the charging system, have been extensively covered, while other endemic SOHC/4 problems, such as melting fuseboxes, have been answered numerous times. When searching, look especially for posts by TwoTired, HondaMan and other experts.
3) I had a prof in business school who would literally yell at us, "Work the numbers! Work 'em backwards!" The same applies to electronics troubleshooting. It often helps to start with the component(s) that are not working and work the problem backwards.
4) If the symptoms involve only a single component, pull it and test it or replace it with a working part. If that fails to provide a solution, or if the problem involves multiple parts, get the wiring schematics for your model.
5) It is very difficult to do serious troubleshooting without a wiring diagram. If you are intimidated by wiring diagrams, start with this
Simplified Wiring Diagram from hondachopper.com. Next, I always find these
Interactive Wiring Diagrams to be helpful. The year in these diagrams may not match your bike; however, the ability to show and hide circuits makes it easier for me to visualize the problem. You should refer to the specific wiring diagram for your bike when doing the actual electrical work on it.
6) Now that you have an understanding of the circuit involved, work it backward. Start with the component you most suspect and work your way, as much as possible, around the circuit. Use the ohmmeter to check switches, wires and connectors because these are likely points of failure on old bikes. Worn wires often break connection or wear to the point that they short to ground.
Electrics may seem like voodoo at first; however, failures are discrete and quantifiable. Plus, when something does not work, there is a specific chain (circuit) that can be mapped from the positive to negative battery terminal. Good Luck!