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The Ultimate Relay, Switch, Sensor, and Diodes Guide


Electrical problems can be terribly difficult to diagnose properly. And to add to your level of frustration, both electrical and fuel-related problems can manifest themselves in the same ways: hard starting, mis-firing, poor performance, back-firing, etc.

Although the electrical systems on XJ bikes are fairly durable, there are a number of known, common problem areas on these bikes, which are compounded by the fact that these bikes are 25+ years old.

The fusebox is the most critical area: the stock one may have been adequate in 1981, but it's now old, outdated, and ready for the dust-bin of history. We carry replacement ATC-style fuseboxes and in-line fuse holders which allow you to easily upgrade your original.

The generator brushes wear down over time, change their electrical characteristics as they age, and need periodic replacement. They are available as complete brushes with holder assemblies, or brushes only. By the way, in a technical sense, your bike is really equipped with an Alternator, not a Generator (as Yamaha calls it), since the output of that electrical-generating device is an alternating (AC) electrical current, which is then rectified into a direct (DC) current via---you guessed it---the rectifier section of your Regulator box......

Anyway: finally, in a general electrical system sense, the wiring harness on your bike is getting old---and like most vehicle wiring harnesses from this era, they aren't (and never were) the most robust things ever made. Corrosion, weak connectors, and other assorted issues will cause you all sorts of headaches and the agony of electrical troubleshooting nightmares if not addressed and remedied.

An exceptional write-up on the electrical system on XJ-series bikes---the good, the bad, and the ugly---can be found at:


I highly recommend that you visit that site and PRINT OUT the FAQ (you never know when a web page might disappear from the web), as it is the "Electrical Bible" for XJ owners!

And finally, if you want to become much more of an expert on your electrical system, we recommend this excellent site……although it was written by/for owners of the Yamaha Vision series of bikes, all of the basic information and some of the bike-specific information is also applicable to the XJ model bikes. Easy to understand, and easy to learn from, the ideas and concepts explained here can really help you become comfortable enough to perform many diagnostics and repairs to the electrical system on your bike.



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