Strato-Saws & Muffler Mods?

[SteveSr]

Hello,

I am wondering if a muffler mod is advised (or not) on strato-saws? I am mostly interested in improving operating margin i.e. making the saw run cooler as happens with non-strato engines. Has anyone done any testing on this? I know that strato charging is supposed to increase scavenging but is this enough such that a muffler mod has a diminishing return with these motors?

I have an MS251 that I will be rebuilding that will be used by volunteers (who can be rough on equipment) and would like to do whatever I can to help it "live long and prosper". Any specifics such as exhaust muffler port area to aim for?

Thanks,
Steve

 

[farminkarman]

Hello,

I am wondering if a muffler mod is advised (or not) on strato-saws? I am mostly interested in improving operating margin i.e. making the saw run cooler as happens with non-strato engines. Has anyone done any testing on this? I know that strato charging is supposed to increase scavenging but is this enough such that a muffler mod has a diminishing return with these motors?

I have an MS251 that I will be rebuilding that will be used by volunteers (who can be rough on equipment) and would like to do whatever I can to help it "live long and prosper". Any specifics such as exhaust muffler port area to aim for?

Thanks,
Steve

Strato or not, muffler mods are a good thing. Most saws come from the factory pretty choked up...some are worse than others. There are varying opinions on how much exhaust outlet is too much, but I don't think there is a hard & fast rule. Plan on re-tuning your carb, which in many cases, requires defeating the limiters on the carb adjusting screws.

 

[SteveSr]

Strato or not, muffler mods are a good thing. Most saws come from the factory pretty choked up...some are worse than others. There are varying opinions on how much exhaust outlet is too much, but I don't think there is a hard & fast rule. Plan on re-tuning your carb, which in many cases, requires defeating the limiters on the carb adjusting screws.

Thanks, I was planning on a re-tune. I haven't torn into the saw yet so don't know how choked up the muffler is. The only reference that I have to go by is for a non-EPA 025 (same displacement) which had a pretty large outlet.