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 quintet. Dear ATVC: I just picked up a Yamaha Raptor 660 and it’s the first Yamaha I’ve ever owned. I am really surprised to hear they ran 5-valve heads. Why not the standard 4? It seems like nothing but more complexity. Even though four valves is the commonly accepted norm (two intake and two […] More »

Don’t chance it. Dear ATVC: So recently I purchased a 2010 Yamaha Raptor 250 for very cheap knowing it had problems. The previous owner said it had a tick when running. Upon further inspection I found a hole on the top of my cylinder head that looks like it was JD Welded. Do I have […] More »

Meet the Live Valve Editions. Honda unveiled two new Talon sport side-by-side models on the eve of Team Honda Talon Factory Racing’s competition debut at King of the Hammers—the 2021 Talon 1000R FOX Live Valve and Talon 1000X FOX Live Valve. Important additions to the rapidly growing Talon family, the FOX Live Valve two-seat models […] More »

Why is there gas going into my pipe? Dear ATVC: After just rebuilding the top end of my 87 Suzuki LT250R, I put it all back together and now when I kick it a few times the exhaust fills up with fuel. I’ve checked over the whole carb and it’s working fine. I’m unsure of […] More »

Dear ATVC: I was wondering why reed valve petals aren’t made of something more durable, like thin metal. This is the second time I’ve had to replace them on my 89 LTR250 in five years. You’re logic is sound but you’re thinking is taking you in the wrong direction. Early reed valves were indeed equipped […] More »

Dear ATVC: I have a few questions about shock springs. First why when a shock blows does the ATV ride bouncier? Secondly, I had my shocks serviced after blowing the rear and notice the outer spring has more coils than it did stock. Do more coils on a shock spring make it stronger? For starters, […] More »