Making an SV650 "Conversion" wiring harness. Article by Tom Monroe

If you are converting your SV650 to an SV650S, one of the tasks you must complete is to prepare a conversion wiring harness.

Unfortunately the connectors on the main wiring harness on the SV650 and SV650S are not the same (fortunately for us, the wire colors are basically the same). If you follow the process I document below, you will wind up with a conversion harness that can be plugged into the main wiring harness of the SV650, and allow it to bridge to the connectors on the SV650S.

First off, lets take a look at wires in the parts manuals of both bikes.

SV650 Main Wiring

SV650S Main Wiring Harness

Click each picture for a larger version.

The main functional difference is that on the SV650, there is a single main wiring harness. The instrument cluser (warning lights, turn signals, etc) plug directly into the main wiring harness. On the SV650S, there is a secondary wiring harness ("wiring harness 2" Suzuki Part Number, 36620-19F10). This secondary wiring harness plugs into the primary wiring harness on one end, and into the SV650S  instrument cluster on the other.

The best solution I believe is to cut the connectors (and about 12" of wiring) off of the instrument cluster of the SV650, and the purchase from Suzuki the secondary wiring harness, and splice the two together. The advantage to this approach is that the modifications to the bike are minimized (no cutting of the main wiring harness). The disadvantage is that the SV650 instrument cluster wiring harness, and the secondary SV650 wiring harness that you purchase from Suzuki are sacrificed. If you at some point wanted to return your bike to its pre-modified state, you would need to purchase a replacement SV650 instrument cluster (of course the odometer will be inaccurate once you swap instrument clusters... this may affect the bike if you sell it later).

Basically, you'll cut the wiring harness off of the instrument cluster right at the instruments... which leaves about 14" of cable. Then you'll take the secondary wiring harness that you purchased from Suzuki, and cut off the end that plugs into "Wiring Harness 1". Finally, carefully splice each wire to the corresponding color wire on the other side of your conversion harness. I cut small sections of heat shrink tubing, and used them to seal the soldiered wires together. After you've connected the wires with the same colors, you'll be left with 3 or 4 wires that do not have exact matches. The wires that remain should be fairly straightforward, and should work if you choose the closest match (I seem to remember Orange to Orange with Black Stripe, for example). Of course, once you've made your adapter harness, you'll need to route it carefully so that your wires don't chafe or bind when the steering head is moved.

Remaining concerns:

My bike has been running in this configuration for more than 2500 miles so far, I've never had any problems. I do have a couple of remaining concerns:

First, there is no parking light on the SV650, so the "third eye" light on the SV650S does not illuminate. I may tap into the parking light on the back of the bike at some time, just in the interest of consistency.

Second, I haven't seen any indications of overloading, however the SV650 has only one headlamp, whereas the SV650S has two. Its possible that I'm overloading the headlight circuit by running both lights. At some point in the future, I may run a seperate, fused line from the battery, and use the headlight power to trigger some type of solid state relay. This would reduce the load on the headlight circuit far below even that of the single SV650 headlight. So far it has not been any type of a problem, even on long rides. I have even done spot checks of the wiring harness, and I don't see any indications of overheating, so I may let this go for a while before I address it.