CR77 Replica Specifications

Engine type: .................. Four stroke twin, 180 degree firing DOHC with two valves per cylinder

Bore & Stroke: ................ 65 x 54 mm

Power @ RPM: .................. 52 BHP @ 12,000

BEMP: ......................... 175 PSI

Power Band: ................... 8,000 to 12,000 RPM with a safety zone of 1,500 RPM extra

Primary Drive: ................ Straight cut gear w/idler, 19-63 (3.31:1)

Clutch: ............................ Multi-plate, Dry

Transmission: ................. Five speed, constant mesh

Gear Ratios: .................. (1) 1.898 (2) 1.459 (3) 1.254 (4) 1.192 (5) 1.000

RPM Drop @ upshift: ........... (1) 27%, (2) 21%, (3) 11%, (4) 8%

Ignition: ..................... MotoPlat Magneto, pointless ignition one sparkplug (14mm) per cylinder

Carburetion: .................. Two Keihin 31mm smoothbore, dual cable operated. Main Jet #110, Jet Needle # RH3, Needle Jet 2.6mm, airbleed type, air jet #250, pilot jet #55, cutaway 2mm, float valve 2.5 mm

Oil Pump: ..................... Twin gear type, low volume, supplying engine and transmission.

Valve Diameters: .............. Inlet 23.6mm, Exhaust 22.0mm

Port Throat Diameters: ........ Inlet 21.0mm, Exhaust 18.7mm

Valve Lift: ................... Inlet 7.0mm, Exhaust 6.0mm

Valve Springs: ................ Dual 70-80lbs on seat, 120-130lbs open

Valve Overall Length: ......... 100mm

Valve Guide Length: ........... 55mm

Valve Weight: ................. 26.9 gm (With retainer, keepers, and 1/3 of spring weight 79.6 gm)

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