Putting A Larger Aftermarket YZ-F Tank On An FX


This article was originally featured in the August 2017 print edition of Dirt Rider

The Yamaha FX line is built specifically for the off-road market, but due to the need for a battery to power a starter and a cooling fan, the aftermarket FX tanks are smaller than the aftermarket YZ-F models by nearly half a gallon. That capacity deficit can mean the difference in an extra lap at a GNCC race—or more time on the trail before needing to return to the truck.

The mechanics at AmPro Yamaha—Corey MacDonald and Lucas Statom—figured out how to solve the problem by using a smaller battery. The cool part is they managed to do it without eliminating anything on the bike, though on more recent adaptations MacDonald has trimmed down the wiring loom considerably. For instance, since the team doesn’t use the cooling fan, the fan relay system with fuses and relevant wiring is removed from the wiring loom. MacDonald even found a way to eliminate the tip-over switch on their racebikes, thus eliminating even more wiring.

According to Lucas, the big secret to making everything fit is to replace the rather large stock battery (4 inches thick) with a much thinner (1.5 inches) Antigravity SC-1 battery and then carving out a notch underneath the seat to accommodate the new battery. Lucas next puts a metal plate in the notched-out area so the rider can’t feel it and then coats it all with Yamabond. In addition to the fuel-capacity gain, there is a huge weight savings and an increase in cranking amps. The YZ-F aftermarket fuel tank is made by IMS, and the cool part is that all the added fuel is down low and rearward.

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