Project Suzuki LTZ400 Turned 450

When Suzuki came out with the Quadsport LT-Z400, it was a major game-changer for the world of sport ATVs. Honda’s TRX400EX finally had some worthy competition in its class, and modifications were being created left and right for them both. Even today, the LT-Z400 is a trusty stead and is worth building up and making it better than stock. Roger Kirkpatrick and his team at Humboldt Motorsports had a Suzuki owner that wanted her machine to go faster and handle better while adding some style to it, so they did just that.

An $10.99 NGK CR8EIX spark plug and Lucas Oil 10-50 synthetic oil was used for this engine build. A quart of this oil will run you around $10.49.
An $10.99 NGK CR8EIX spark plug and Lucas Oil 10-50 synthetic oil was used for this engine build. A quart of this oil will run you around $10.49.

MORE POWER
To start the process off, a $419.95 Millennium Technologies bigbore 450cc kit was installed on the Quadsport, and Humboldt ported and polished the cylinder head for an addition $198. Stage 1 Hot Cams were installed for $299. Now that the Suzuki had bored-out cylinders with higher compression, it required more fuel and needed to suck in more air. Roger mounted up a 39mm Keihin carb tuned by Humboldt Motorsports. This accounted for more gas to be added to the air-to-fuel mixture, which the Suzuki now had to consume 92-octane pure fuel for $6.49 a gallon.

Next stop was to allow the bigbore engine to breathe better, so a $219 Twin Air Power Flow kit was mounted onto the Suzuki. They used K&N oil-filter treatment on the new higher-flowing air filter.

Humboldt Motorsports installed an FMF PowerCore 4 slip-on muffler onto this machine for more low-to-midrange power gains.
Humboldt Motorsports installed an FMF PowerCore 4 slip-on muffler onto this machine for more low-to-midrange power gains.

The last step in the power equation for this machine was a FMF PowerCore 4 slip-on muffler that sells for $299. With all of these mods that Humboldt Motorsports bolted onto their customer’s Suzuki, its power increase was big through the whole range.

The rear Sand Gecko tires on this machine hook up really well in the sand and cost around $89.99 a tire.
The rear Sand Gecko tires on this machine hook up really well in the sand and cost around $89.99 a tire.

GETTING THE POWER TO THE GROUND
When you build a big motor, it’s important to focus on the essential parts that are now taking more wear from the increase in power. Humboldt installed a $233 EBC DRCF clutch kit that helps handle the new load from the big-bore 450cc Suzuki engine. Roger and his team also changed the sprockets to JT Steel sprockets in the front and rear that cost around $69. The front sprocket has 14 teeth and the rear now has 39 teeth. An ATV G Series EK chain was also installed for a reasonable price of $119. Next, new tires and wheels for slinging sand were installed on this project bike. The new tires were installed on $78.95 ITP aluminum wheels. The front Sand tire is a 21×7-10 tire, while the rear Sand Gecko is sized to 20×119. Now, every ounce of power this Suzuki’s engine could put out reached the ground with great traction.

Humboldt Motorsports porting and polishing of the Suzuki cylinder head helped increase power through the whole range.
Humboldt Motorsports porting and polishing of the Suzuki cylinder head helped increase power through the whole range.

HANDLING, CONTROL AND PROTECTION
No matter how powerful an ATV is, it’s only as good as it handles, and one of the best upgrades you can install on a quad is aftermarket suspension. Roger bolted up a set of Lone Star Racing +3-inch A-arms up front for $599.95 that helps provide the machine with a wider and more stable footprint for slow- and high-speed riding. A LSR Axcalibar Pro +3-inch axle for $448.95 gave this Suzuki a nice wide stance for better cornering and high-speed riding. Elka suspension was the next upgrade to this quad, with Stage 1 shocks up front and a $999 Elka Stage 4 shock in the rear. Elka Suspension can provide a very smooth and predictable ride for all types of riding, whether it’s in the sand or out on the track. As far as hand controls go, the machine kept a stock setup on it, which is actually quite good. The stock bars provide a good riding position, and the levers are decent. For footpegs and heel guards, Humboldt Motorsports went with the $349.95 Pro Armor Race pair with Fat Pegs. They also installed Pro Armor’s under-belly chassis protection for another $139.95.

ITP Sand Star tires are mounted on the front of this machine on ITP aluminum wheels. They help with cornering hard in sand.
ITP Sand Star tires are mounted on the front of this machine on ITP aluminum wheels. They help with cornering hard in sand.

THE TEST RIDE
Roger asked a good friend of his—Nicholas Hickey of Nitro Circus, Monster Jam and Moore FMX—to test out this project Suzuki Quadsport LT-Z400 turned 450. Here are his comments: “The power increases on this bike are smooth yet powerful, mainly in the mid-to-top end. I could lug the motor into a corner, then snap on the throttle, and it would hit just how a 450 would, but was very controllable, and it never felt like the quad would come out from under me by snapping the throttle. The new clutch was pretty nice as well. It had a smooth operation, and I mainly only needed to use two fingers to pull the lever in. The rear Sand Gecko tires really helped the Suzuki lay down its linear power easily.

Elka Stage 1 coil-over shocks were used on this machine, and they run at $649.99 a pair. Elka’s Stage 5 shock is their best for a sport ATV but are around triple the price.
Elka Stage 1 coil-over shocks were used on this machine, and they run at $649.99 a pair. Elka’s Stage 5 shock is their best for a sport ATV but are around triple the price.

“The Elka suspension felt smooth in both slow- and high-speed riding. I could stab the front brake entering a turn, and the front shocks wouldn’t go through all of their travel, which was good, then lay on the throttle to swing the rear end around and the rear shock would soak up any chop with ease. Having this quad be widened by LSR in extending the A-arms and rear axle made a big difference in handling as well. Going fast, it was predictable and more stable over rough sections. The widening mainly helped with cornering. I could throw the bike hard into a corner, and it didn’t want to tip like the stock setup would have. The Pro Armor nerfs with Fat Pegs are one of my favorite improvements for handling. Since I like to use my feet and legs to help move a quad around, the wider pegs gave me more room to move my feet around, and they gave me great traction under my boots.”

MTA Distributing and Parts Unlimited were a big help with this build. You can get parts through both companies at your local dealerships.
MTA Distributing and Parts Unlimited were a big help with this build. You can get parts through both companies at your local dealerships.

FINAL THOUGHTS
We couldn’t leave out the awesome color scheme on this machine. Humboldt Hydragraphics did a great job at hydrodipping the stock plastics with a blue carbon fiber look. That will run you around $499 and looks killer. After hours of work and even more hours of testing, this Humboldt Motorsports-built machine turned out to be a dream for the customer. She had no complaints and was very happy about how it turned out, as it performs well and is reliable.

Humboldt Hydrographics did a great job by dipping the stock Suzuki plastics with a blue carbon fiber look. The custom Humboldt Motorsports front bumper is another nice touch for $199.
Humboldt Hydrographics did a great job by dipping the stock Suzuki plastics with a blue carbon fiber look. The custom Humboldt Motorsports front bumper is another nice touch for $199.

CONTACTS
EBC: (702) 8826-2400, www.ebcbrakes.com
EK: Contact nearest dealership
ELKA SUSPENSION: (450) 655-4855, www.elkasuspension.com
FMF: (310) 631-4363, www.fmfracing.com
HUMBOLDT HYDROGRAPHICS: (707) 444-9545
HUMBOLDT MOTORSPORTS: (707) 269-0991, www.humboldtmotorsports.com
ITP TIRES AND WHEELS: (909) 390-1905, www.itptires.com
JT SPROCKETS: (770) 948-8880, www.jtsprockets.com
K&N: (800)-858-3333, www.knfilters.com
LONE STAR RACING: (480) 834-2990, www.lsracing.com
LUCAS OIL: Contact nearest dealer, www.lucasoil.com
MILLENNIUM TECHNOLOGIES: (888) 779-6885, www.mt-llc.com
NGK: (877) 473-6767, www.ngksparkplugs.com
PRO ARMOR: (888) 312-7667, www.proarmor.com
TWIN AIR FILTERS: (800) 749-2890, www.twinair.com

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