Tech Tips

Testing Salvage Components Using a Multi-Meter

Written by  December 31, 2005

When it comes to the junkyard wars of buying used motorcycle parts, do you really know if these are as good as the counterman tells you? Electrical components from the dealer arena most assuredly will leave you speechless when you have the price given to you. Your best bet is going salvage. If you have ever been to a motorcycle salvage yard, you know that each and every bike there has a story. Some have serviced their original owners quite well, and others may not have been so fortunate.

I believe that saving money today is on everyone’s New Year’s resolution list, and quite frankly, it is a smart way to go. In the new parts business not many dealerships will take a return on any electrical component these days. This is why the salvage yards have so many different types of components, but do they work? This is where I must insist on having a good service manual with the electrical schematics and tolerances. I keep pointing back to electrical more and more mainly because bikes today are fuel injected and have 2, 4, and even 8 spark plugs with coils and ignition wires that will go bad in due time.

Budget constraints and extremely high prices are why I will never turn down a good used part over a new one. The price of some ignition boxes will blow you away. I recently installed a new CDI or capacitive discharge ignition box on a late model Kawasaki 600, and it was over $500 retail (ouch!). Calling around to the salvage yards can be worthwhile and save lots of money and time.

Careful diagnosis is the key when isolating the cause of the failed component. This will be the job of your multi-meter. They come in all shapes sizes and prices and are a necessary tool to diagnose electrical issues. Not only do they break down ohms, AC and DC volts, and amperage, they will also make troubleshooting that much easier. So if you do not have a multi-meter, they have really come down in price. Buy according to your budget. Some meters are exclusive to automobiles. They may be too technical for your application. Please purchase the correct meter for the job.

One of the first things is to make sure you have a new battery in the multi-meter. If the battery is weak the readings will be off and will give you false tolerances. You can also test stationary alternators with a continuity test to ground. This can be done by testing the alternator at the connector for each leg and then to ground. This is explained in depth in your service manual.

When it comes to regulators, rectifiers or combined, these do a specific job. Don’t be confused. The regulator keeps the voltage constant, and the rectifier side changes alternating current or AC from the alternator to direct current or DC. So, as you can see, these are very important parts and may be very expensive if misdiagnosed. Most salvage yards rarely check the used electrical components before they sell them as they deal with such a volume of wrecked bikes and blown engines. The last thing they want to sell you is a bad part, so taking a chance and having your multi-meter at your side might save you quite a bit of money and especially time. Over time, even something as simple as an ignition coil can go bad. This is where the ohms part of the meter is helpful. It can not only tell you how much primary resistance is present but it will also tell you how much secondary resistance you have at the spark plug cap. They sell different electrical testing equipment for coils, and the list goes on.

The multi-meter, if used correctly, can be just as effective and will be a tool that can be used for multiple items. Testing battery voltage is a test that I have mentioned before and will give a reading that identifies the actual charging status of your motorcycle. Normally these components are plentiful at salvage yards and can be tested with the parts removed from the bike. Control boxes, bulbs and even points can be tested with multi-meters and tested accurately. So do not be discouraged on testing components from a used source.
I have been to several yards and when I asked if I could test a certain component they never gave me any problems about that. Most likely they will test it for you.

Saving time as well as money is the best way to really know the bike you have. Keeping your bike running and in top notch condition is not only the smart thing to do but the safe thing.

I want to wish each and everyone the safest and happiest of this New Year.

B-safe out there

By Dave Miller