If you're looking to squeeze every bit of torque out of your machine, a raptor 700r big bore kit is probably sitting right at the top of your wishlist. It's one of those modifications that completely changes the personality of the quad. The Raptor 700R is already a beast from the factory, but there's something about that extra displacement that makes the bike feel like it's finally breathing the way it was meant to. It's the classic "no replacement for displacement" mentality, and for most riders, it's the best way to get that "rip your arms out of their sockets" power.
Choosing to go the big bore route isn't just about bragging rights at the dunes, though that's certainly a perk. It's about changing how the power is delivered. When you increase the bore, you aren't just looking for a higher top speed on a flat road; you're looking for that raw, grunting torque that helps you pull through deep sand or lug up a steep, rocky trail without constantly dancing on the gear shifter.
What Exactly Does a Big Bore Kit Do?
In the simplest terms, you're making the hole in the engine bigger. By increasing the diameter of the cylinder, you allow for a larger piston. This extra volume means the engine can pull in more air and fuel during the intake stroke. More air and fuel equals a bigger explosion, and a bigger explosion translates to more force pushing that piston down.
Most people looking for a raptor 700r big bore kit end up looking at the 105mm options. The stock bore on a Raptor is 102mm. Jumping up those extra few millimeters might not sound like much on paper, but in the world of single-cylinder engines, it's a massive jump. It takes the engine from the stock 686cc up to around 734cc. You'll feel that difference the very first time you thumb the throttle.
What's cool about these kits is that they generally provide a "fat" power curve. Instead of just getting a little peak power at the very top of the RPM range, you get more power everywhere. It makes the Raptor much more forgiving to ride because you have so much more grunt available right off the bottom.
Choosing the Right Kit for Your Riding Style
Not all kits are created equal, and your choice depends on what you're actually doing with the bike. Are you a weekend warrior hitting the trails, or are you trying to build a dedicated hill climber?
For most guys, a "bolt-on" style kit is the way to go. These usually come with a new cylinder (the "jug"), a high-quality piston, rings, and the necessary gaskets. The beauty of these kits is that they are designed to work with your stock crank. You don't have to split the cases or get into the really heavy bottom-end work unless you're planning on going even bigger with a stroker crank.
Then you have to think about compression. A lot of raptor 700r big bore kit options offer different compression ratios. If you want to keep things simple and keep running 91 or 93 octane pump gas, you'll want to stay around the 11:1 or 11.5:1 range. If you're okay with buying expensive race fuel or mixing in some octane booster, you can bump that up to 12.5:1 or higher. High compression gives you an even snappier throttle response, but it definitely adds a bit of a headache when it comes to finding fuel at a remote gas station.
The "While You're In There" Factor
One thing I always tell people is that you shouldn't just slap a big bore kit on and call it a day. The engine is a system. If you're putting in a bigger piston to create more power, you need to make sure the rest of the engine can keep up.
Fueling and Tuning
This is the big one. If you install a raptor 700r big bore kit and don't adjust your fueling, you're going to have a very bad time. The bigger engine is going to want more fuel. If you run it lean, you'll melt that expensive new piston faster than you can say "engine rebuild." You'll need a good EFI controller—something like a Power Commander or a Vortex ECU—and ideally, some time on a dyno to get the mapping right.
Airflow
The Raptor 700R already has a pretty decent intake, but once you go big bore, you really want to let it breathe. A high-flow air filter and an aftermarket exhaust are almost mandatory to see the real gains from the kit. If the engine can't get the air in or the exhaust out, that bigger piston is basically just working against a vacuum.
Camshafts and Valvetrain
If you've already got the top end apart, it's the perfect time to drop in a Stage 2 or Stage 3 cam. A bigger bore loves a cam that can hold the valves open a little longer. It's one of those things where the total is greater than the sum of the parts. A big bore with a stock cam is good, but a big bore with a matched cam is incredible.
Is It Reliable?
This is usually the first question everyone asks. "Is my Raptor going to blow up if I put a big bore on it?" The short answer is: not if you do it right.
The Raptor 700R engine is notoriously overbuilt. It's a tank. As long as you use a high-quality raptor 700r big bore kit from a reputable brand and you're diligent about your maintenance, it'll last a long time.
The main enemies of a big bore engine are heat and poor tuning. Bigger explosions generate more heat. You might want to look into an upgraded radiator or at least a high-performance coolant. And, as mentioned before, making sure your air-fuel ratio is spot on is the best insurance policy you can buy. Don't cheap out on the tuning.
The Installation Process: A Reality Check
Installing a raptor 700r big bore kit isn't exactly a five-minute job, but for someone who's comfortable with a wrench, it's totally doable in a weekend. You don't have to pull the whole engine out of the frame, which is a huge plus. You can do the top end with the motor still bolted in.
However, you have to be clean. Dirt is the enemy of an open engine. You'll want a good torque wrench, a service manual, and plenty of rags. One tip: be extremely careful with the circlips on the piston. There is nothing more heart-wrenching than hearing a ping and realizing a tiny metal clip just fell down into your crankcase.
If you aren't comfortable timing an overhead cam engine, there's no shame in taking the cylinder and head to a shop. But for those who like to get their hands dirty, there's a real sense of pride in hearing that big-bore thump for the first time knowing you built it yourself.
Final Thoughts on Going Big
At the end of the day, a raptor 700r big bore kit is one of the most rewarding upgrades you can do. It takes a bike that is already fun and turns it into a monster. It's about that feeling of pulling a wheelie in third gear without even trying, or being the guy who makes it to the top of the "test hill" while everyone else is getting stuck halfway up.
It's not just about the numbers on a spec sheet. It's about how the bike feels under you. That extra displacement gives the Raptor a soul that feels even more "uncorked" and ready to play. If you've got the itch for more power and you've already done the basic pipe and filter mods, the big bore kit is the logical next step. Just remember to tune it right, keep it cool, and hold on tight—because it's going to be a completely different ride.