Duncan Racing's Complete 450cc/460cc Engine Performance Package for the Yamaha YFZ 450

Includes
Fat Boy 4 Complete Exhaust System, 450cc or 460cc Forged JE Piston Kit (12-1 compression), Cylinder Bore and ReNikasil Coat, head gasket, Billet Camshaft, HD Valve Springs w/Titanium Retainers, Shortened Bronze Guides, DR Head Porting (with guides out) and Valve Seat Cut, Instructions, DR Tech Support. *Cylinder Head is returned assembled and ready to install.

Kit Options

Camshafts
Baja/Cross Country Cam
X34 Grind "Bottom/Midrange" Power Gain (Lift: .350”/.340", Duration 250/253?)
Motocross Cam
X12 Grind "Midrange/Top End" Power Gain (Lift: .362”/.353", Duration 262?)
*DRI uses billet camshafts only for the YFZ 450.
**DRI only uses this design because it is the most reliable option for this model.
Hardfacing a stock OEM YFZ 450 camshaft is not feasible because stock cores suffer severe distortion at the journals during the modification process.

Compression
11-1 (Pump Gas)
12-1 (Race Fuel)

Displacement
450cc or 460cc

Cores
Kit Price is plus any OEM parts.
Customer must send in to DRI their Cylinder(optional),
Head, Crankshaft, Camshaft for modification. (or purchase new cores)
Customer must send in stock cam cores so DRI can remove IN and EX Cam sprockets and Compression Release Mechanism and install them on new Billet Camshafts.
Customer may purchase from DRI new cylinder, head, valve cotters and camshaft cores (needed for cam sprockets) for $1,150.
*If cores are purchased new from DRI, customer will not be required to send their parts to DRI.
DRI will ship new modified and assembled head along with freshly bored and re-plated cylinder.
**If new core route is taken, customer will be responsible setting valve lash.

Delivery Schedule
Average lead time for 460cc National kit is 4 to 5 weeks.
Due to heavy demand it is difficult for DRI to stock newly modified cores.