How much larger engine will fit your Doodlebug minibikeThe stock 2.5 HP is just plain weak. Thanks?

Most Doodlebugs come with a 6.5 horsepower internal combustion engine. If you are looking at going bigger, you can swap out the existing engine with up to a 10 horsepower. Any larger, and you risk damaging the minibike. Beyond the engine, you would likely also need to upgrade your carburetor, and clutch.