The YFZ is a great quad, but like every other quad, it has its problems. Luckily for us, Yamaha is good enough to admit them and create fixes for them. One of those problems on early-release models of the YFZ is a battery discharging problem.

The YFZ charging system is made to supply a maximum charging rate with the headlights switched to the ON position, at low to medium engine rpms. In some cases, including low speed with cooling fan running frequently, or continuous high RPM riding (like a race) you may need to have the headlights in the ON position to keep a fully charged battery. When racers remove the headlights to get rid of weight or for whatever reason, they might be causing the battery to discharge itself. (If your lights are still mounted, leave them on all the time.)

In order to fix this problem, Yamaha has created a Resistor Kit. The kit includes a higher temperature Thermo Fan Switch for the radiator to minimize current draw, and a ceramic resistor which takes the place of the headlights to maximize the charging rate. It is a very easy fix, for what might be a sucky end to your day if your battery discharges during a race.

The first step is to install the new thermoswitch. It is located on the right side of the radiator. Make sure to put a drip pan underneath to catch the small bit of radiator fluid that will come out.

The next thing you have to do is remove your regulator rectifier. That's the funny-shaped thing with ribs on it just under the front nose piece of the quad. The kit comes with two mounting brackets that the ceramic resistor has to be placed in.

It is a very tight fit, but it does fit. The mounting bracket lets it sit just below the regulator rectifier and is held on with the supplies bolts.

From there its just a few simple wires to plug into the main harness and sub harness.

This was a very easy install, that anybody could do. Not everyone will experience this battery discharging problem, but if you are a racer and don't have your lights installed there is a very good chance of it happening. So why take the chance when all you have to do is spend 15 minutes and install this?

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