MTD 78 Series User Manual

Crankshaft, piston and connecting rod
115
Engine specifications chart
Specification New Min New Max Service Limit
in. mm in. mm in. mm
Bore (digit 2&3 of the model number)
78 3.071 78.02 3.072 78.03 3.080 78.23
83 3.268 83.02 3.269 83.03 3.277 83.24
90 3.544 90.02 3.544 90.03 3.553 90.26
Crank pin min. diameter
78 1.298 32.98 1.299 32.99 1.296 32.92
83 1.417 35.98 1.417 35.99 1.414 35.91
90 1.417 35.98 1.417 35.99 1.414 35.91
Piston pin min diameter
78 0.713 18.10 0.716 18.20 0.711 18.07
83 0.795 20.19 0.795 20.20 0.793 20.15
90 0.795 20.19 0.795 20.20 0.793 20.15
Connecting rod max. ID (crank side)
78 1.300 33.02 1.300 33.03 1.302 33.08
83 1.418 36.02 1.418 36.03 1.420 36.08
90 1.418 36.02 1.418 36.03 1.420 36.08
Connecting rod max. ID (piston side)
78 0.717 18.22 0.718 18.23 0.719 18.25
83 0.796 20.22 0.796 20.23 0.797 20.26
90 0.796 20.22 0.796 20.23 0.797 20.26
Connecting rod to crank pin max.
running clearance
78 0.001 0.03 0.002 0.05 0.003 0.07
83 0.001 0.03 0.002 0.05 0.003 0.07
90 0.001 0.03 0.002 0.05 0.003 0.07
Connecting rod to crank pin max.
side clearance
78 0.006 0.15 0.026 0.65 0.049 1.24
83 0.006 0.15 0.026 0.65 0.049 1.24
90 0.006 0.15 0.026 0.65 0.049 1.24
Crank shaft run out (max)
78 0.001 0.03 0.001 0.03 0.001 0.03
83 0.001 0.03 0.001 0.03 0.001 0.03
90 0.001 0.03 0.001 0.03 0.001 0.03
Crank shaft end play (max)
78 0.016 0.40 0.035 0.88 0.035 0.88
83 0.000 0.00 0.022 0.55 0.022 0.55
90 0.000 0.00 0.022 0.55 0.022 0.55

MTD 78 Series Specifications

General

Brand	MTD
Model	78 Series
Category	Engine
Language	English