Ontario Moto Tech Cam & Jetting Recommendations

CB400F Specifications

Cam Timing at 1mm Valve Lift

H401 Road & Track Cam
IN 15º - 45º 7.20mm
EX 45º - 15º 6.90mm

Tappet Clearance
0.10 (.004in)
0.10mm (.004in)

Piston to Cylinder Clearance
Street Use: 0.03mm - 0-04mm (.0012 - .0016)
Racing Use: 0-04mm - 0-06mm (.0016 - .0024)

Precision boring and honing is one of the most important factors in oil control, bore and hone cylinders to as smooth as possible finish, and be sure that it is under the given clearance.

Ring Gap: Same as stock Compression Ratio: 10.5:1

Minimum Valve to Piston Clearance: IN   1.2mm
                                                                     EX 1.5mm

Cylinderhead Tightening Torque: 2.5 kg. m. (18 ft. lb.)

Ignition Timing: +5º advance from stock

Carburetor Jetting: Specific carburetion setting is given as a guidance, to offer you a most favorable point in which to start. However, there may be some jetting difference according to altitude, air cleaners and other variables.
STOCK ENGINE WITH “YOSHIMA” PIPE: Change main jets to number 80 or number 85. Leave needles in stock position.
458cc ENGINE WITH “YOSHIMA” PIPE: For street use, change main jets to number 85 and if you experience rough idling, lower the needles one notch down. for racing, use main jet number 95 or number 100 and raise the needles one notch up.
492cc ENGINE WITH “YOSHIMA” PIPE: For street, change main jets to number 95 and if you experience rough idling, lower the needles one notch down. For racing, use main jet number 100 or number 105 and raise the needles one notch.

Note: We strongly recommend that after any new piston and rings or bearings are installed, you break them in at least 200 miles (300 miles preferred) by keeping the engine rpm under 6,000. Although we had great results with synthetic oils (name brands), a new motor must be broken in first with conventional petroleum oil.