The SmartCarb is a precision air-and fuel-metering instrument designed to push the limits of mechanical fuel atomization. A proprietary Venturi concentrates and accelerates airflow for better fuel atomization. This high-velocity airflow is focused directly at the metering rod, providing better fuel atomization for a more complete combustion burn, a power increase and better fuel economy.

There are only two adjustments, and both can be made externally by hand. The SmartCarb is designed to automatically compensate for ambient air-density factors—including elevation, temperature and humidity—by combining the air-density-sensing capabilities of the metering rod with internal venting of the float bowl to the airbox. These two patented systems work together to create a sealed system that provides consistent air/fuel ratios, regardless of changing conditions throughout the day. No more jets.


We installed the Smartcarb on our long tern 2020 Beta 300RR. Installation looked a bit intimidating due to the oil injection, as the 36mm SmartCarb they sent us comes with its own wiring harness for the TPS with a fuse and 12-to-5-volt converter built in, but the instructions were very good. It’s actually a very simple process. Remove the stock carb. Remove the tank. Loosen both air boots. Disconnect your oil-injection line, and loosen the subframe to swing it up out of your way. The Smart Carb uses the stock throttle cable, so all you do is thread that into the new throttle cap and hook up the cable to the new slide on the SmartCarb.

The carb fits in very easily, and there were no fitment issues. The SmartCarb has two plugs on it. One plugs into the stock TPS plug; the other plugs into the new harness. A check-engine light  could come on upon startup because you have introduced a new TPS, and the ECU needs to learn the new voltage parameters. If the light stays on, SmartCarb claims a few engine starts and stops will clear the light. If it persists, they recommend unplugging the ECU for 30 seconds to reset it.


Starting the first time required no choke, and it idled perfect. Once warmed up, it felt a touch lean (tinny), so we adjusted the metering rod in the richer direction. To do this, you shut the bike “off,” hold the throttle open to bring the slide up to the throttle cap and adjust the gold clicker knob on top of the carb. The gold knob engages into the metering rod. Clicking it to the right richens the circuit, left leans out the circuit. Once we felt the desired throttle response, we hit the trail.

The SmartCarb-equipped Beta hit way harder than it did with the standard Keihin carb. It was revvy and altered the smooth bottom flow into a motocross-type powerband and the machine ran much hotter. On our hard-enduro loop, we were using first gear more (didn’t need it with the Keihin), and it boiled over several times (which it had never done prior).

After chatting with the techs, they felt that it was too lean and needed a richer needle. Because our riding is technical with a lot of short-shifting, the new needle would address the negatives we had felt. Once we installed the new needle, we regained the lost bottom power and the machine ran cooler. It still pulls harder and longer than stock, and it felt like the new needle energized the roll-on appeal of the Beta. We also got dramatically improved fuel economy (in our testing about 20–25 percent),which was a huge boon. Overall, it was a big win in the performance category across the board.

While the standard Keihin worked well at altitude, the SmartCarb is superb. Elevation and temperature changes had almost no effect on the carb, as if this were a bolt-on EFI!

The SmartCarb is a great mod for the two-stroke owner (at least on our Beta 300RR) looking for a tunable power increase, better fuel economy, and fewer jetting hassles with elevation and temperature changes.

PRICE: $699–$774


On the Beta, there’s an oil injection system. This doesn’t interfere with the Smartcarb, but care should be taken during installation.
The gold knob on top engages into the metering rod. Clicking it to the right richens the circuit, left leans out the circuit.
Installation looks intimidating due to the oil injection and the wiring harness for the TPS, but the instructions were very good.


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