Small Engines (Lawn Mowers, etc.): how to tune a chain saw, screw out, air leaks

Question
Hi my mum brought a craftop Chainsaw the cc is a ht/5200 it has a problem can you tell me how to tune it pleas?

Answer
hi  

it might pay to get your local shop to tune this  in the matter of safety
but if you decide to tune using guide below  i cannot accept any liabilty  

might pay to let me know what particular problem your saw has  

tuning can be a hard one /  but here is general  guide   (use at your own risk )

pull muffler - check for carbon, clean and decoke ex port  if need and refit muffler

replace plug, same type and heat range as one removed  drain fuel tank, clean tank and replace fuel filter- check manifold and carb bolt tightness and barrell bolt  tightness
refill tank  fresh 2 stroke mix   50:1  mix  ie   20 mils oil + 1.0 litre of petrol

put 20 mils of  good quality 2 stroke oil into container 1st  then add 1.0 litre of petrol only , mix  then fill the saw tank

make sure air filter  is clean and re-oiled if foam element type or wash the flock filter in hot water and tap it out and let dry

make sure compression and spark are in top order   or else the carb adjustments will be hopeless
make sure engine has no air leaks as these make unit hard start , idle unreliably, stall , have low power and make engine run hot  and leads to damage

find the hi and lo speed adjustment mixture screws
( do not go below 1.0 turn out from lightly seated )

turn the lo speed one in all the way untill it seats lightly then back it out 1 1/4 turns out from lightly seated these are  base settings  for most saws

repeat for hi speed mixture screw  

start engine  and rev engine and turn the hi speed mixture screw out a fraction more   
you should hear the engine hold back at rev if its 4 stroking (keep the time you have  the engine revving to as little as time possible  ( we do not want the engine revving clean  with no load on it or it will lean out and blow if it does )


let trigger go  and let machine go back hi idle speed  which is usually just below clutch engagement speed or slightly lower

give couple of quick stabs on the trigger and if the engine does not hesitate on quick acleration lo speed setting should be about right  but if it stumbles  turn the lo speed needle  out a fraction more

note do not run machine with settings for hi or lo at any less than 1.0 turn out from lightly seated or damage can occur


cheers