KCS 62CC MANUAL
7
Needle Adjustments (Cont'd)
• Adjust the Low End needle until you achieve a smooth idle and a reliable transition to high
throttle. Generally if the motor “stutters” or “coughs” in the mid range or when the throttle is
advanced, the low end needle is too rich and possibly even the high end needle. If the motor
dies quickly, the low end is probably lean.
• Don't set the needles overly rich to protect the engine. Operating the motor overly rich not
only reduces power, it creates other problems such as poor transition, pre-mature carbon
build up, fouled plugs, excessive exhaust residue, sticking rings, airframe vibration, and
overall rough running.
Trouble Shooting
Motor won't start:
• Check battery voltage (should be 5.0+ volts) and all ignition connections, wiring and switches.
Wires can break from vibration near connectors. Check and/or swap out regulator.
• Does fuel move towards the carb when the prop is flipped? If not, check tank venting, clunk
position, and fuel lines for leaks. Is the choke plate closing completely? Is the carb or carb
mount loose causing an air leak? Air leaks on the engine usually show as fuel seepage.
• Is throttle set at idle or slightly higher after motor “pops” and choke is opened?
• Make sure prop is flipped over with authority. The ignition won’t fire at low speed.
• If a lot of fuel drips from carb, the motor might be flooded. If so, remove and dry, or replace,
the spark plug. Try starting again without using the choke. If engine doesn't fire after several
flips, try choking again.
Other issues:
• RPM won’t go over 3,500 to 4,000: The connector between the ignition module and ignition
sensor may be plugged in backwards. Check the color of the wires leading into the
connectors to make sure that the polarity is correct.
• Broken prop bolts: In order for bolts to shear, some type of side loading (shear) movement is
usually required. If the bolts are tightened correctly (nothing moves), prop bolts will rarely
break. It’s a good idea to replace prop bolts routinely. Check prop bolts before each flight!
• Excessive vibration: Check that the low rpm needle setting is not too rich. Check prop and
spinner balance. Make sure ignition timing is correct. Check the firewall and motor box area
of the aircraft for movement, poor glue joints, etc. This area must be rigid! Some aircraft on
the market are lacking in this area and may require additional glue and/or structure. Poor
quality or contaminated fuel can cause rough running.
• Pink or purple colored cylinders: These colors indicate engine temperature has been too high
at some point. Check that needle settings are not too lean, air flow for cooling is sufficient,
and oil/gas mixture is correct.