The science behind the process. When it comes to a four-stroke engine, there is a very simple process taking place every single time your piston rockets up and down its cylinder bore – your intake and exhaust valves open and close once per every two crank revolutions. That means your piston goes up twice and […] More »

The mysterious stack. Dear ATVC: I’m looking at a carburated Z400 that the ad states is equipped with velocity stacks. What is that and what does it do? That’s a solid question. You don’t hear a whole lot about them these days and it gets even more confusing because they are often called things like […] More »

This is a drive belt but the machine is not belt driven. Dear ATVC: I’m sorry if this is a stupid question but I don’t know much about mechanics and I’m afraid to post it on a public forum for fear of getting lambasted by those who do. When an ATV has a belt transmission, […] More »

Because even the mere risk of stalling sucks. Dear ATVC: Do manual transmission quads that you can shift without engaging a clutch use a centrifugal clutch to accomplish this? I believe you can stop these quads in gear without killing the engine. Can these quads be left in high gear and accelerate from a standstill? […] More »