PROJECT KFX450: A bigger bore, pipe, and suspension rebuild

A bigger bore, pipe, and suspension rebuild

As Captain Kirk used to say, “Scotty, we need more power!.” Like Kirk, ATV performance riders are always looking to get extra horsepower for their rigs. Not to mention, added comfort, good looks, better handling and extra protection. We’ve even more picky than Kirk was.


To achieve these ends, we contacted a variety of aftermarket companies to help us in our goal of making our stone stock ’08 Kawasaki KFX450 a better all around rocketship. One of the first companies we contacted was Max Power, out of Madison, Wisconsin.
Like Captain Kirk’s Scotty, they are masters of extracting quantum leaps of power from ordinary engines. They carry bigger bore piston kits and a host of other power enhancers, such as aftermarket pipes, cams, and porting packages. With their help, you should be able to get the maximum amount of horsepower out of your standard spaceship ATV.
We had them install one of their KFX 470 Stealth engine kits on our KFX450 Kawasaki. This kit consists of a standard OEM cylinder, bored out to 468cc, and plated with their Apticote 2000 ceramic coating. They can do the rebuild for you, if you send them your stock OEM cylinder, but it will cost you an additional $300 plus shipping and handling. Your other option is to simply order their Stealth piston kit ($680) and do the install yourself. We had a Hot Cams Stage 3 cam ($360) also installed with our bigger bore engine kit, to get the max effect of the power increase with a higher revving camshaft.


Our next step was to bolt on a Jardine R2 complete exhaust system to our KFX 450. This consists of a stainless steel header pipe that runs to an aluminum exhaust canister. Total price of this kit is $525, and it comes with a built-in spark arrester, you can order a quiet core insert for a slight additional change. We also ordered up one of Jardine’s easy to use fuel injection card readers, which allowed us to fine tune the Jardine exhaust with the KFX’s fuel injection system. It retails for $229, is available directly from Jardine Products, and makes working on the fuel injection system on the Kawie simple.
Since we felt the KFX450’s stock suspension could use further improvement, but didn’t want to invest in a pricey set of new shocks, we had I-Shock perform a rebuild of our KFX’s stock  front shocks ($199). You will have to remove the stockers and send them to I-shock for the rebuild. But they offer a quick turnaround on their shock rebuilds, and in a matter of only a week, we had our shocks back to us and ready for action. It doesn’t hurt that they offer a  100 percent satisfaction guarantee with their rebuilds.
Another important consideration for us was to install a steering damper on our KFX 457, to improve the machine’s overall handling. We put one of GPR’s ATV steering stabilizers ($495) on our KFX to tame the excessive feedback going to the rider’s arms when riding over rough terrain.
We think this unit is one of the best ones on the market, and it has a built-in dial adjuster, mounted on the handlebar, that allows you to slow or speed up the steering damper effect on the handlebar,  even when riding. Nice.
A few more mods we added to our machine were a set of Pro Armor nerfs, ($309.95) with competition footpegs, and a huge Pro Armor bumper gracing the front end. We left our wheels and tires stock for now, but we plan on installing aftermarket replacements once we wear the stockers out.

Next, we rolled our machine out to one of our favorite test tracks. We immediately noticed the quicker hook -up and acceleration. We ran it against a stock KFX450 we had, and it literally would pull it by several quad lengths in our drag races. Once out on the track, the Stealth KFX470 kitted Kawie simply ate up the stocker.
The Max Power/470cc engine kit gives the KFX a harder hit all the way through the power spread. The bottom end is meatier, and transitions into a solid mid-range that continues to rev out on top with the help of the new cam. This is exactly the type of power that helps almost any rider, by providing a wider, more usable torque hit that lets you leave the machine in a higher gear and pull out of turns instead of having to downshift and over rev.
Our Jardine exhaust note was not offensive, and it works perfectly with the Max Power 470cc engine kit to make the KFX a much more enjoyable machine to ride. The power is good for trails or the track, and as long as you don’t sticker up your quad, like we did, you could get away with other riders thinking you were running a “semi-stocker” with a pipe. That’s the reason they call it a “Stealth” kit in the first place. Don’t ask, don’t tell.

The other area our KFX470 excelled in, especially over the stock KFX450, was in how much better our revalved and reworked I-Shock suspension performed. Since we had a stock shocked KFX450 to compare it to, we were extremely pleased with how our I-shock rebuilt suspension performed.
The overall feel of the I-Shock modified front shocks was night and day different from the stocker. The stocker  kicked and bounded through the whoops, while our 470 tracked straight and true. It also didn’t jar the rider in the worst of the bumps.
We give high marks to the GPR steering stabilizer, as it tamed the stock KFX’s excessive headshake, and its rough ride in the most severely whooped-out sections of trail and track.

Overall, we were extremely satisfied with the results of our modification package. Our Max Power KFX 470 rips all over a stock KFX 450. It also offers up a smoother, more plush ride than the stocker, in all manner of terrain conditions, thanks to the revalved shocks and GPR steering damper. That’s a combination that will be hard to beat. Now all you have to do is not let anyone know you’re riding a 470 instead of a 450. We’ll leave it to you to decide how to handle that particular issue.

Engine Performance:
Max Power KFX470 Big Bore kit    $630
Max Power installation kit    $300
Max Power Optional head porting    $450
Hot Cams Stage 3 cam    $360
Jardine RT5 exhaust full system: Aluminum/stainless    $525
Jardine fuel injection card    $229
Suspension/steering performance:
I-Shock (Hydrodynamics USA),
shock re-valve (fronts)    $199.95
GPR Stabilizer    Low mount steering Stabilizer    $525
Pro Armor nerfs    $309.95
Pro Armor Dominator front bumper    $134.95

Max Power Inc.
3001 Progress Rd.
Madison WI 53716
(608) 224-2524
Hot Cams Inc.
2751 Parkside Circle
Urbandale, IA 50322
(515) 402-8005
Jardine Performance Products
1180 Railroad Street
Corona, CA 92882
(951) 739-1623
I-Shock—HydroDynamics USA, Inc.
9303 Bond Ave. Suite C
El Cajon, CA 92021
(619) 390-2430
GPR Stabilizer
8715 Dead Stick Rd.
San Diego, CA 92154
(619) 661-0101


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