JT Sprockets Steel Rear Sprocket Review: CRF300L Rally Gearing

The author of this review was looking forward to writing about the JT Sprockets steel rear sprocket for the CRF300L Rally. The stock sprocket was replaced with a 42-tooth steel sprocket, which changed the bike’s character.

The author wanted to wait until all power mods were completed before adding the gear ratio changes. The installation was simple, but the author made a mistake by trying to turn the hex socket bolt instead of the backing nut, which rounded out one of the soft OEM bolt heads.

The sprocket fit exactly as an OEM replacement should, and the stock chain still fits, though it requires the rear wheel to be adjusted far forward. The author found that the 42-tooth sprocket made the CRF300L Rally’s power much easier to use, especially at highway speeds.

The engine feels more responsive because it is closer to its horsepower peak, giving it enough reserve to handle changing road conditions. The tradeoff is a reduction in top speed, but the bike maintains highway speeds with greater confidence and requires fewer downshifts on grades or into headwinds.

The author is glad to accept this compromise because it makes the CRF300L Rally perform better at the speeds they ride. The 42-tooth sprocket also affects the speedometer’s accuracy, which is about 9% over actual speed.

The author is not going to put the 13-tooth JT Sprockets countershaft sprocket on the bike with the 42-tooth rear sprocket, but will try the 13-tooth countershaft sprocket with the 40-tooth stock sprocket next time they change the rear tire. The 13/40 combo drops the gearing by 2.6% compared to this 14/42 pairing, and the author is curious how that will feel on- and off-road.

The JT Sprockets 42-tooth steel rear sprocket turned out to be the icing on the CRF300L Rally Project Bike’s engine modifications cake for just $31 MSRP. It doesn’t transform the engine or create horsepower that wasn’t there, but it fundamentally changes how accessible that power feels.

Whether cruising on flatland freeway, climbing mountain grades, whipping through the twisties, or crawling through rocky trails, the Rally is simply easier and more enjoyable to ride. Sometimes the best performance upgrade isn’t adding power; it’s making better use of the power you already have.