DR Power RapidFire 5.5 HP Subaru (July 2013 - Present) Engine Manual - Manual (Page 16)

16 DR ® 5.8 HP ENGINE
2. INSUFFICIENT ENGINE POWER OUTPUT:
TROUBLE CAUSE REMEDY
When increasi
ng
throttle, speed increases
slo
w
or speed decrease and engine
stops
running
Fuel sup
ply
s
ystem
Air in fuel line or fuel line clogged Exhaust air or dredge fuel line
Main oil flow hole is not adjusted properly Readjust
In carburetor, needle valve hole and main oil flow
hole clogged. Clean and blow to get through
Fuel shutoff is clogged up. Clean, replace damaged part
Too much carbon deposit in combusting chamber.
Clear away
Too much carbon fouling in muffler and exhaust
pipe. Clear away
Air filter is clogged up. Clean air filter paper element
Intake pipe is leaking Repair or replace
Poor compression
Piston or cylinder or piston ring is worn Replace worn parts
Air leakage from the surface where the cylinder block
contacts the cylinder head. Replace cylinder gasket
Too big or too small valve clearance. Readjust
Valve tightness is poor. Repair
3. ENGINE NOT RUNNING SMOOTHLY:
TROUBLE CAUSE REMEDY
Knocking sou
nd
Piston, cylinder or piston ring is worn excessively. Replace worn parts
Piston pin and piston pin hole are worn excessively. Replace piston or piston pin
Tie rod small head is worn excessively. Replace tie rod
Roller bearing for crankshaft main shaft is worn. Replace roller bearing
Abnormal combustion
Engine is too hot Troubleshoot reasons for hot engine
Too much carbon deposit in combustion chamber Clear away
Improper gasoline brand or low gasoline quality Replace with qualified gasoline
Spark lackin
g
There is water in float chamber Clean
improper spark plug electrodes clearance
Adjust
Something wrong with induced coil or related parts Check and replace damaged parts

When testing the spark plug, never hold the high- voltage wire of the spark plug with a wet hand.

Make sure there is no spilled fuel outside the engine and that the spark plug isn’t dipped with fuel.
 To prevent fire, keep sparks far away from the spark plug mounting hole.