Up until Yamaha finally added fuel injection to their YFZ450s, there have not been a ton of major changes to them. The “old-reliable” YFZ450s are out there in droves, and we thought it would be fun to breathe some new life into an old dog.

YFZ450 PROJECT BUILD: The YFZ450 Project ATV in the Air on a Jump

2006 YFZ450 Project

For this project, we found a 2006 YFZ450 that was set up as a desert/trail machine. It was in pretty good shape but in need of some love to the engine. The motor was tired and needed to be freshened up to be as good as the rest of the machine. The quad already had a longer and wider a-arm set up with Elka front shocks that were bought off an ex-racer along with a large IMS tank. We wanted to clean up the good parts that were there and make this thing run like it should as a good desert, trail and dune machine.

We rebuilt the entire engine with a new Hot Rods bottom end kit along with a Cylinder Works big bore kit (478cc) with Hot Cams stage two cams. The stock cylinder was pretty worn, so we needed a new piston and gaskets anyway. Why not go big? The Cylinder Works big bore kits are completely stealth – yes, they totally look stock but are 3mm larger inside.

The power increase is great with the big bore and cams. It stays very reliable using the stock valve springs. Race Tech modified the stock rear shock to work with the oversized front and longer axle.

Watch this video to check out more on this sweet YFZ450 project!

Products

Parts Available at Rocky Mountain ATV/MC
YFZ450 PROJECT BUILD: Cylinder Works Big Bore Cylinder Kit 478cc YFZ450 PROJECT BUILD: Hot Cams Stage 2 Camshaft YFZ450 PROJECT BUILD: Hot Rods Complete Crankshaft Assembly – Heavy Duty YFZ450 PROJECT BUILD: Hot Rods Crankshaft Main Bearing and Seal Kit
Cylinder Works Big Bore Cylinder Kit 478cc Hot Cams Stage 2 Camshaft (Intake and Exhaust) Hot Rods Complete Crankshaft Assembly Hot Rods Main Bearing and Seal Kit
YFZ450 PROJECT BUILD: Cometic Complete Gasket Kit YFZ450 PROJECT BUILD: Uni Air Filter YFZ450 PROJECT BUILD: FMF Titanium Megabomb Header Pipe YFZ450 PROJECT BUILD: FMF Factory 4.1 Silencer with SS Mid-Pipe
Cometic Complete Gasket Kit Uni Two-Stage Air Filter FMF Titanium Megabomb Header FMF 4.1 Slip-On Muffler
YFZ450 PROJECT BUILD: Tusk Foot Peg Nerf Bars with Heel Guards YFZ450 PROJECT BUILD: Tusk Comp Series Aluminum Front Bumper YFZ450 PROJECT BUILD: Tusk Parking Brake Block Off Plate YFZ450 PROJECT BUILD: Tusk Adjustable-Width Racing Axle
Tusk Foot Peg Nerf Bars with Heel Guards Tusk Comp Series Front Bumper Tusk Rear Brake Block Off Tusk Adjustable-Width Racing Axle
YFZ450 PROJECT BUILD: STI Tech 4 XC ATV Front Tire YFZ450 PROJECT BUILD: STI Tech 4 XC ATV Rear Tire YFZ450 PROJECT BUILD: Renthal Front Sprocket YFZ450 PROJECT BUILD: Renthal Rear Sprocket
STI Tech 4 XC 21×7-10 Front Tire STI Tech 4 XC 20×11-9 Rear Tire Renthal Front Sprocket Renthal Rear Sprocket
YFZ450 PROJECT BUILD: Renthal 1 1/8” FatBar YFZ450 PROJECT BUILD: Renthal ATV Dual Compound Grips – Half Waffle YFZ450 PROJECT BUILD: Renthal O-Ring Works Chain YFZ450 PROJECT BUILD: IMS Fuel Tank
YFZ450 PROJECT BUILD: Hinson Clutch Basket YFZ450 PROJECT BUILD: Hinson Inner Clutch Hub YFZ450 PROJECT BUILD: Hinson Pressure Plate YFZ450 PROJECT BUILD: Hinson FSC Clutch Plate and Spring Kit
Hinson Billet Clutch Basket Hinson Inner Hub Hinson Pressure Plate Hinson Clutch Fiber Steel Spring Kit
YFZ450 PROJECT BUILD: CV4 Radiator Hose Kit YFZ450 PROJECT BUILD: CV4 High Pressure Radiator Cap YFZ450 PROJECT BUILD: Attack Graphics Machine-Specific Graphics/Decals at Rocky Mountain ATV/MC
CV4 Formed Silicone Coolant Hoses CV4 High Temp Radiator Cap Attack Graphics Custom Graphics Kit

YFZ450 PROJECT BUILD: The 2006 Yamaha YFZ450 Project Build

Conclusion

With these mods and some good jetting, we were in business. While this build is a pretty huge overhaul of an already great machine, you can take advantage of gaining increased power, handling, reliability or comfort by implementing portions of our build to fit your riding style and budget.

If you want to see more of this YZF450 project quad, check out the June issue of ATV/UTV Action.

What are your thoughts? Would you have done anything differently? Please let us know in the comments!

Technician Disclaimer

By Jay Clark