ms460 and ms660 running too lean

[themechanic]

Hello I picked up two eight month old saws a stihl ms460 and a stihl ms660 that bolth had been scored by running straight gas, the ms660 I replaced the piston with an older 066 piston and honed the cylinder and it run's but overheats I thought the base gasket was the problem so I used indian head gasket sealer on the old base gasket it does not overheat as bad but it still overheats. the second saw a ms460 did not come with a carb so I used a stihl 044 carb I bought a piston kit and it runs but overheats badly I noticed that it idles erraticly so I immediatly stopped the saw the piston is not scored but this has got me stumped.If there are any tricks to find out where my air leak or leaks are coming from I would greatly appreciate it.

 

[TimberPig]

To find the leaks, you need to pressure test the crankcase and cylinder. Do a search on here and read for hours about it.

Once you know the case is properly sealed, then the carbs can be adjusted correctly.

 

[CaseyForrest]

First is the 044 carb is not jetted for a 460. Unless you re-jet the carb there isnt enough adjustment in the high side to get it enough fuel. (I may be wrong and the experts will be along shortly to straighten it out.)

Not sure on the 660, but if you suspect an air leak a pressure and vac test are in order before anything else is done.