4 Cycle Engine Models:

Note - Your engine model number may have a letter after it.
Example K301S or K321AQS or CV22S this is a Version Code.
Version Codes are:

A - Special Oil Pan

C - Clutch Model

G - Generator Application

P - Pump Model

Q - Quiet Model

R - Reduction Gear

S - Electric Start

T - Retractable Start

ST - Electric Start and Retractable Start

EP - Electric Plant

Aegis Liquid-Cooled 
Horizontal Shaft  LH640,  LH685, LH690,  LH755,  LH775
Vertical Shaft  LV625, LV675, LV680
 

Command Pro CS
Horizontal Shaft  CS4, CS6, CS8.5, CS10, CS12, Hydro 12.75

Command / Command Pro
Horizontal Shaft  CH5, CH6, CH11, CH12.5, CH13, CH14, CH15, CH18, CH20, CH22, CH23, CH25, CH26, CH730, CH740, CH745


Vertical Shaft  CV11, CV12.5, CV13, CV14, CV15, CV16, CV17, CV18, CV20, CV22, CV23, CV25, CV26, CV460, CV461, CV490, CV491, CV492, CV493, CV624, CV675, CV724, CV730, CV740, CV745
 
Courage

SV470, SV480, SV530,  SV540, SV590, SV600
 

Go-Kart
XKE6
 

K-Series
K91, K141, K161, K181, K241, K301, K321, K341, K361,

K482, K532, K582, K660, K662, KT17, KT19, KT21, KT17 Series II, KT19 Series II

Magnum
Horizontal Shaft  M8, M10, M12, M14, M16, M18, M20
 
Vertical Shaft  MV16, MV18, MV20

Triad
TH16, TH18, TH520, TH650