Skills | Two-Strokes to Four-Strokes

Sean Collier Breaks Down The Transition

Skills | Two-Strokes to Four-Strokes

Photo by Casey Davis

It is pretty obvious that the sport of motocross has evolved way past the two-stroke era, and racing at the highest professional levels will continue to be four-stroke motorcycles. This doesn’t change the fact that there are still two-strokes being raced and ridden globally, all the way down to the grassroots amateur level. The reality is most kids learn how to ride and race aboard 50cc, 60cc, 80cc, and 125cc two-stroke machines before jumping to the next competitive level bike, a 250cc four-stroke. There is certainly a transition period for anyone that must go back and forth between the styles of engine and their inherited handling characteristics.

While filming our video last year, aptly named Transworld Motocross Premix, we did a segment with a talented rider named Sean Collier who has gathered a cult following based on his ability to muscle around his KX500 with ease. Sean also sometimes lines up for select Lucas Oil Pro Motocross nationals for fun, competing at the highest level aboard a KX450, so transitioning back and forth from a two to four-stroke quite often is something the friendly Californian is very used to. Sean even raced both the 450 class and the 2015 FMF Two-Stroke National Challenge on the same day at the Glen Helen national a couple years back. It’s safe to say the guy knows a thing or two about transitioning back and fourth between the two different types of machines, and let us in on a few tips to consider when making the switch back and forth.

Power Delivery: Naturally moving to a four-stoke, the biggest thing you would notice first is the power delivery. The power is a lot more usable, you have a lot more traction out of the hole, and it also feels like it has a lot more power initially, especially when you are coming straight off a two stroke. Two-strokes don’t have as much hit, but the way it’s delivered can sometimes be more violent so controlling traction and the rear end can be more difficult on a two-stroke. The way the four-strokes deliver the power is like a tractor, lots of torque. You need to remember how to deliver the power on each type of bike.

Shifting Points: A two-stroke doesn’t have that torque that a four-stroke has, so it’s really critical to be shifting and stay in the right gear at the right time. If you go into a corner in too high of a gear on a four stroke you can be alright and the bike is going to still want to pull through it, with a little bit of clutch and a raise of the RPM’s. On a two-stroke if you go into a corner in too high of a gear it’s just gonna bog. You have to be in the right gear!

Engine Braking: Engine braking is the biggest difference. There’s really not any engine braking on a two-stroke, it’s minimal. You are going to be over taxing the brakes more on a two-stroke if you aren’t riding the bike properly. You have to learn to carry your momentum into a corner with a two-stroke, rather than race from point A to point B. With a four-stroke you can really utilize the engine breaking when entering a corner to help slow you down, and that is a lot different.

When Jumping: When you’re on a four-stroke, it is going to have that feeling where it wants to throw you over the front a little bit more, where with the two-stroke it’s a little bit more of a free feeling due to not having engine braking, and it’s not going to have that same inertia as the four-stroke. You definitely have to adjust your position on the bike accordingly and prepare for that.

Modern Technology: The first time I went to ride my 500, I brought it to my buddy’s track and it was in a little higher elevation. It literally wouldn’t even run, and I was so bummed. So on a two-stroke you have to get the bike dialed in and jetted properly, and I find that part pretty fun. When you get to a track on a four-stroke everything is self-adjusting, and that kind of took that away now without the carburetors. So if you are getting on a two stroke you may have to re-acclimate yourself to that quickly, getting the bike set up properly, especially if you are in elevation.

Don’t Forget The Premix: I was like twelve years old or so, and this is the first and only time I ever did this. I had about an eighth of a tank left, and my buddy had some random fuel laying around with no oil in it, and I just threw that in the bike. I ended up riding it for the rest of the day and went through that entire tank. When I got home and told pops what happened, he was obviously worried that I damaged the bike. Surprisingly after tearing it down there was minimal damage! So obviously that’s critical, make sure your gas is mixed up for the two-stroke or you’re screwed!

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