In an effort to help others out there that share the same passion for the XS650 as we do here at ST Customs we have created this helpful tips section to provide information regarding upgrades and maintenance of your prized machine



In an effort to help others out there that share the same passion for the XS650 as we do here at ST Customs, we have created these helpful tips section to provide information regarding upgrades and maintenance of your prized machine.

Whether you are doing a full top to bottom custom build or just maintaining your machine as it is, this information should be quite helpful to you.



The headache from hell

Most donor bikes are in some form or another, a neglected machine that has spent the past several years languishing in someone’s barn or worse yet in the back yard under a dripping tree. This sort of treatment adds to the notorious function ability of the stock wiring harness on the XS650, which was never really good…even when they were new. The wiring system has always been the Achilles’ heel of the XS bikes. Some have been hacked apart and cobbled back together by merchants of electrical tape and wire nuts. They utilized older glass tube fuses, which are getting harder and harder to find at the local auto parts store so a swap out to the more modern blade type fuses is a great aid.

We like to keep things neat and tidy so it is our practice to completely do away with the stock wiring harness and build a new much simplified system from scratch. Now we take the neat and tidy to a next level by having the main harness pass through the frame itself and utilize small project boxes at each end of the bike to keep the entire final wiring connections all in one place and out of the weather.

On many of our bikes we utilize a modified stock battery box that houses a newer type (and much smaller and lighter) Li-Ion battery. This also serves as a mounting point for the regulator/rectifier and still maintains the stock mount for the starter solenoid for those who choose to start their bike via a button. Some folks use batteries and some folks don’t…that’s a personal choice. On our bikes we always provide both electric and kick-starting capabilities in case a given customer may want to hit the button as opposed to kicking it over. I’m an older guy and my back ain’t as young as it used to be so that starter button comes in plenty handy for me.

Since all of the stock add-ons are removed from the wiring system many of the original mounting points on the battery box are repurposed for other uses. The headlight reserve lighting unit mounts, for example are utilized as the mounting points for the electrical box containing all the wiring connections on the rear of the bike. Again, this helps in keeping things neat and tidy. We also add a couple mounts to the battery box for the fuse block we use and its placement allows it to be out of the way yet easily accessible when needed.

The stock wiring harness contains over a hundred wires and they change color and back-track through itself so this can be a very daunting thing for most people to approach. By looking at the entire wiring system in a more simplified way makes it much easier to understand what does what. The overall premise is quite simple…things that need power need to have a positive lead (power) and a negative lead (ground) it is, after all a DC system we’re dealing with here. So set aside color and look at function instead and things become much clearer and easier to comprehend.

The examples we show are the way we do our wiring. You do not have to do it this way at all these are all just suggestions that we have found to be both easy to install and reliable going down the road.

- OIL -

The fluid of life for an engine

The oil system on these bikes is a good system and although many do add oil coolers and high-flow oil pumps it has been our experience that the stock system works just fine. The problems arise when that oil is not kept fresh and clean. The XS650 should get an oil change at least every 3000 miles (or sooner depending on your riding style) it uses 2500cc’s (two and a half quarts) of 20/50 weight oil specifically designed for 4 stroke motorcycle engines…which means NO you can not use the cheapo oil from the automotive isle at the supermarket. The motor has two oil filters one located behind the round cover on the right-side engine cover, and the other (the sump oil filter) is located on the bottom of the motor behind the 6-bolt cover plate. This cover plate also has one of the two oil drain plugs on the motor. These oil drain plugs are 23mm in size.

As a general rule the oil filter should be changed every other oil change and the sump oil filter should be changed annually.

Many modified bikes no longer have the center stand on the frame and getting the bike to stand up straight during an oil change can be a challenge. With the bike leaned to the left (resting on the side stand) much of the old oil is trapped on the left side of the motor when trying to drain the old oil out so fresh oil can go in. Blocks can be used to prop the bike up straight or straps can be utilized on the handle bars hung from the rafters in a garage or even tossed over the limb of a tree. The important thing is to get the bike sitting straight and level so all the old oil can get out.

Most all motorcycle lift jacks do not allow easy access to the oil drain plugs while supporting the bike so finding an alternative method of supporting the bike during an oil change is invaluable.

«-A helpful tip for oil changes is that your basic everyday 2-liter soda bottle has the same thread pattern as the oil inlet opening and is a great oil fill funnel. You screw it into the oil filler opening and it provides a large downspout for pouring in the oil. Once done just unscrew it and put the dip stick back in there.


The Spark of Life

These bikes used (over the course of their production run) two types if ignition systems. From 1970 to 1979 they used a points-based ignition system and in 1980 they changed to a CDI system.

On all of our bikes we use an electronic ignition system made by Pamco coupled to a new PMA charging system and this is a vast improvement over the older stock system.

The 1980 and beyond bikes need to have an advance rod, and bushings added to the cam so that the electronic ignition system can be utilized on those later motors.

The original stock systems have a very weak spark even when they’re working top-notch the spark is weak. With the newer electronic systems, the spark is greatly enhanced and thereby better combustion is achieved and better overall performance is obtained.

There are new CDI systems available nowadays as well so that can be an available alternative as well. These systems have been rigorously tested and they work great and are very reliable.

These new CDI systems are sold by Hughes Hand Built out of Ashville, North Carolina.



Give me the juice

The stock charging system on the XS650 was never the greatest of systems and being an alternator/stator set-up, it needs 12 volts just to work right. With a PMA system the needed electricity is created by the unit spinning around as the motor runs so it gives you the option of running your bike without a battery if you choose to do so. You will have to have a high-capacity capacitor so the excess juice has somewhere to go.

We primarily use the XS-Charge PMA system sold by Mike’s XS but Hughes Hand Built sells a solid system as well.