Diagnosing air leak on ms260

[Tempestv]

I have a 260 that was ported and muffler moded by the previous owner. It's been a great saw for a number of years, but just recently it started running very fast at idle. I tried to tune the carb, but it seems impossible to tune properly. It either won't idle at all, or its running way way to fast. I backed the idle screw back until it wasn't engaging the throttle, and it didn't make a difference. I'm thinking some sort of air leak. What would be the beat way to go about diagnosing such a problem?

 

[Deleted member 135597]

Get a mityvac vacuum/pressure pump off amazon

 

[jltrent]

Check the impulse line as that was what was wrong with mine.....

 

[pioneerguy600]

The 026 and MS260 most frequently have leaking seals on the flywheel side, the flywheel needs to be popped off to check it.

 

[Mad Professor]

If no leaky rubber, and carb is not suspect, what pioneerguy said above.

A OEM gasket set is cheaper than seals and it comes with seals. My dealer will install both seals for $15 if you bring him a clean saw stripped down with flywheel and clutch/oiler off. Those 026/260 seals are a PITA if you don't have the tools. So for ~ $30 you have OEM seals installed, and a set of gaskets if ever needed. Add in $ for a flywheel puller tool if you don't have one, they fit a lot of stihl saws.

 

[Ozhoo]

Don't forget the intake hose, especially if the av is getting sloppy