TROUBLESHOOTING GUIDE
PROBLEM
CAUSE
SOLUTION
REPLACEMENT PARTS LIST
FS120-A
Exhaust Pipe Set
FS120-B
Valve Set
FS120-C
Rocker Arm Set
FS120-D
Pushrod Set
FS120-E
Wrist Pin Set
FS120-F
Choke Set
FS120-G
Cam Gear Cover Set
FS120-H
Thrust Washer Set
FS120-I
Rotor Bolt Set
FS120101X
Case
FS120102
Backplate
FS120103
Cylinder Head
FS120110
Rear Bearing
FS120111
Backplate Gasket
FS120112
Head Gasket Set
FS120204
Connecting Rod
FS120210
Crankshaft
FS120218
Woodruff Key
FS120231
Piston
FS120232
Sleeve
FS120236
Ring
FS120606
Muffler Assembly
FS120711
Rocker Cover
FS120714
Cam Gear
FS120801
Carburetor Assembly
FS120816
Carburetor Intake O-Ring
FS120831
Intake Pipe Gasket
FS120863
Carburetor Body
FS120873
Intake Pipe
12109
Cam Gear Bearing Set
12114
Pressure Nipple
12518
Cam Gear Cover Bolt Set
12819
Fuel Nipple Set
12832
Idle Stop Screw
12833
Detent Spring
12845
Needle Valve O-Ring
12861
Needle Valve
12860
Needle Valve/Housing Set
40123
Intake Pipe Bolt Set
400109
Front Bearing
50122
Rocker Cover Bolt Set
61122
Backplate Bolt Set
80123
Head Bolt Set
80228
Prop Nuts/Washer Set
80810
Idle Needle Set
80866
Throttle Arm
1) Engine does not start
A) Failed glow plug
A) Replace glow plug with a new one
B) Glow Starter not charged
B) Fully charge glow starter
C) Engine not being turned over fast enough
C) Use an electric starter
D) Old fuel
D) Replace with new fuel
E) Engine flooded with too much fuel
E) Remove glow plug and expel fuel from cylinder
2) Engine does not draw fuel
A) Idle mixture screw set too lean
A) Reset idle mixture to factory setting
B) High Speed Needle Valve fully closed
B) Reset high speed needle valve to factory setting
C) Hole or crack in fuel lines
C) Replace fuel lines
D) Defective fuel tank
D) Replace fuel tank
3) Engine vibrates excessively
A) Propeller out of balance
A) Balance propeller
B) Spinner out of balance
B) Balance Spinner
C) Engine or motor mount loose
C) Check all mounting bolts and tighten securely
4) Engine does not transition
A) Failed and/or wrong type glow plug
A) Replace with new recommended glow plug
B) Old and/or wrong type fuel
B) Replace with new recommended fuel
C) Idle mixture set too lean
C) Set idle mixture richer
D) Idle mixture set too rich
D) Set idle mixture leaner
E) Valves out of adjustment
E) Readjust valves to correct gap
5) Throttle barrel does not
A) Idle stop screw out of adjustment
A) Turn idle stop screw counterclockwise until
close completely
barrel closes completely
B) Idle mixture set too lean
B) Reset idle mixture to factory setting
6) Engine Overheats
A) Engine running too lean
A) Richen high speed needle valve
B) Cowl too restrictive
B) Open vents in cowling
C) Improper fuel used
C) Use recommend fuel