These are the known mechanical and performance specifications for your 1986 Honda CMX 450 Rebel.
Basic Specs

Engine
Displacement447.00 ccm (27.28 cubic inches)
Type
DetailsTwin, four-stroke
Max RPM
Compression9.3:1
Bore/Stroke75.0 x 50.6 mm (3.0 x 2.0 inches)
Valves/Cylinder3
FuelingCarburettor. dual 29.3mm venturi
Ignitioncapacitive discharge
Exhaust
Lubricationwet sump
CoolingAir
Fuel Economy & Polution
Fuel Consumption
Fuel Capacity12.00 litres (3.17 gallons)
Emissions
Chassis
Frame Typedouble cradle
Rake58.0°
Trail135 mm (5.3 inches)
Front Suspensiontelescopic forks
Front Travel
Rear Suspensionswing arm shock absorber
Rear Travel
Seat
Seat Height690 mm (27.2 inches) If adjustable, lowest setting.
Alt. Seat Height
Total Height1,170 mm (46.1 inches)
Total Length2,230 mm (87.8 inches)
Total Width800 mm (31.5 inches)
Ground Clearance155 mm (6.1 inches)
Wheelbase1,530 mm (60.2 inches)
Dry Weight174.0 kg (383.6 pounds)
Wet Weight185.0 kg (407.9 pounds)
Wheels & Brakes
Front Tire/Tyre100/90-18 56S tubeless
Rear Tire/Tyre140/90-18 70S tubeless
Front BrakesSingle disc
Front Brake Diameter
Rear BrakesExpanding brake (drum brake)
Rear Brake Diameter
Wheels
Comments
info taken from Honda Service Manual 61MM201