SkyHawk Engine Trouble Shooting guide
GruBee SkyHawk 2 cycle engine trouble shooting guide:
( 4 things are needed for an engine to run > FUEL, AIR, COMPRESSION, and SPARK )
Symptom Possible causes and corrections
No Start #1. Carburetor choke: Choke Lever down if engine is cold, if engine is hot; choke lever must be up.
#2. Possible flooded engine. Try starting with throttle wide open. If no start > go to step #3.
#3. Check spark plug; Replace if fouled and or worn electrodes are found. Pedal spin engine with spark plug remove to clear possible wet cylinder. Install new a spark plug: If still no start > go to step 4.
#4. Use plastic pliers to hold spark plug wire end approximately 1/8" to 3/16" away from spark plug tip and spin engine over by pedaling bicycle with rear wheel held up. If spark is strong and normal then go to step #9. If no spark then go to step #5.
No Spark #5. Check CDI ignition blue and black wire connections. If good and tight > go to step # 6.
#6. Disconnect kill switch wires and try starting. If engine starts then look for an unwanted ground in the kill switch circuit. If the engine still does not start > go to step # 7.
#7. Std. SkyHawk: Check magneto coil with an ohm meter. Look for approx. 300 to 350 ohms across blue and black wires. Check for loose screws and rust corrosion. If an open or shorted coil is found replace with a new magneto coil. If magneto coil is known to be good > go to step # 8.
#8. Replace CDI module. If the no start engine condition is still present > go to step #9.
#6 / #7 SkyHawk SuperRat & SuperMouse; On these models the CDI & Magneto Coil are integral.
Good Spark but Engine will Not Start #9. Possible Flooded engine: Go back to step #2. If engine is not flooded > go to step #10.
#10. Check for fuel restriction. Remove line at carb. and check for fuel flow. Clean filter on tank valve. Clean any inline filter. Remove carburetor from intake tube, unscrew cable top and remove slide valve. Clean needle and jet opening with automotive carburetor cleaner, reassemble and install back on engine. If still no start > go to step #11.
#11. Check for air leaks at carburetor intake manifold tube. Check for loose manifold nuts, Check for loose carburetor and or damaged intake gasket. Clean clogged or dirty air cleaner. Make sure engine does not have fuel in bottom of crankcase due to unwanted entry of drip down gas from above gas tank. If still no start > go to Step #12.
#12. Check throttle cable. Make sure it is moving the slide valve up and down in carb. Make sure the pac-man clip on the needle is installed like shown in owner's manual. If still no start after cable and slide valve inspection > go to step. #13.
#13. Check crankcase for possible air leaks. Check left and right oil seals on ends of crankshaft to see if tightly seated in front of bearings. Push the piston down to lowest position and plug up exhaust and intake ports so a hand held compression pump can be used to see if any air escapes from crankcase. Be careful to not blow out the oil seals with too much pressure. If the crankcase gasket is leaking and needs replacing it's best to have a qualified mechanic replace the gasket. If no air leaks are found and you still have a no start engine condition > go to step #14.
#14. Run a cylinder compression check by removing the spark plug and installing an appropriate compression gage. Plug the exhaust and intake ports with a custom made flat plate. Use a hand held electric drill or an air wrench to turn the crankshaft at the magneto nut. Note: If the engine turns over easily with the spark plug or a compression gage seated in the engine head this means you have a blown head gasket, broken rings, or a possible hole in the top of the piston. You will now need to remove the 4 head bolts and head to make further checks. Note: If compression is good and no problem is found > go to step #15.
#15. Replace or overhaul the carburetor and correctly set idle speed adjustment. If still you have a no start engine condition then probably it's best to consult with a qualified small engine mechanic as somewhere in the trouble shooting process something has been over looked.
Low Engine Power Try moving the pac-man clip on the carburetor needle downward to the next slot. Your sea level altitude may be different than that of the China Carburetor factory calibration. Be cautious as a tight piston cylinder fit requires an engine break-in period.
Check for > Clogged muffler > Clogged exhaust port > Fuel restrictions > Low compression > Poor ignition spark > Too much oil in gas or improper air/fuel mixture. Clean carb. jets and air filter; Check for a crankcase gasket leak or leaking oil seal.
Idle Speed Adjust carburetor idle screw air / fuel mixture setting. Refer to your owner's manual. Adjust cable stroke slide valve adjustment at top of carb if possible, some early made YD CNS carbs do not have this feature.
Slipping Clutch Check clutch gear wheel for worn or greasy clutch pads. Replace worn clutch pads and adjust bearing plate tension as described in owner's manual.
Clutch Squeal Check for bent clutch rod. Remove the clutch plate and lubricate clutch plate movement being careful to not get any oil on the 15 clutch pads. Check clutch tension adjustment. Refer to your owner's manual for step by step instructions.
Clutch will not Disengage With clutch engaged check for 1/16" slight free play on the left side engine clutch arm to insure correct adjustment. Remove clutch cover on right side of engine and check for possible stuck clutch plate or bent clutch rod. Clean off any rust and lubricate the clutch plate movement.
Clutch will not Engage Clutch cable may be adjusted too tightly. Check for 1/16" free play in clutch arm on left side of engine. When clutch is engaged the clutch arm on the left side of engine should be setting in an approximate parallel line up with the side of the engine. Remove clutch cover and check to see if the clutch plate is stuck open in the disengaged position.