Stihl MS291 Surging when Started and Need to Keep Throttle On Or Engine Will Quit

[dmnichol]

My Stihl MS291 is surges (high RPM) when first started and after starting, i need to keep the throttle on it or else the engine will quit. I did a positive pressure leak test, and couldn't find any leaks except in the middle of the engine cylinder. Here is a video showing the leak on youtube:


Is there a gasket or seal there that might have blown or do I need to buy a whole new cylinder?

 

[Wood Doctor]

I received a Stihl MS291 for repairs in my shop about two years ago. It had almost no compression left at all. New top end piston and cylinder kit was so expensive that even the local Stihl dealer said "Forget that. Might as well buy a new 291."

 

[SteveSr]

My Stihl MS291 is surges (high RPM) when first started and after starting, i need to keep the throttle on it or else the engine will quit. I did a positive pressure leak test, and couldn't find any leaks except in the middle of the engine cylinder. Here is a video showing the leak on youtube:


Is there a gasket or seal there that might have blown or do I need to buy a whole new cylinder?

Saw overheated and melted the glue that holds the transfer port cover on. The saw is toast!

 

[Müller]

This MS291 is one sad saw, it just died although I used Aspen fuel and used it moderately and who does such crap with transfer ports glued on. The price for that is ridiculous. I think even my chinese saw is better, it has metal body and oil adjuster.

 

[dmnichol]

Agreed! Sorry to hear yours went too! It was the first chainsaw and I thought I was paying more money for a quality saw.

An update, I jammed some JB Weld High Heat around the area where the transfer port was leaking and this did solve leak that was causing the surging and bad idling but I haven't put it through it's paces yet. Will post an update when I do.