661 muffler mod progression w/thermocouple

[huskihl]

From the test I have seen done it looks like the baffle removed and maybe enlarge the existing exhaust port a little (maybe not even at all)….

Also this is a stock saw so it’s not ported….i was watching redbulls videos and seems like a little back pressure seemed to do better…

He has hundreds (if not thousands) of hours doing R&D testing on the 661, but his findings mostly apply to his ported saws.
Anytime you open up a hole or add more deflector area, you’re allowing the engine to rev and make power higher in its RPM range at the cost of some forgiveness. It’s not like there’s a one size fits all muffler mod. What works best for a short bar isn’t going to be the best with a long bar. It’s all about the happy medium

 

[Khntr85]

He has hundreds (if not thousands) of hours doing R&D testing on the 661, but his findings mostly apply to his ported saws.
Anytime you open up a hole or add more deflector area, you’re allowing the engine to rev and make power higher in its RPM range at the cost of some forgiveness. It’s not like there’s a one size fits all muffler mod. What works best for a short bar isn’t going to be the best with a long bar. It’s all about the happy medium

Pretty sure the one video I watched was only a stock 661, but yes he does have many videos….

You would think that just opening the existing port a little (on any saw), would be beneficial if not only for getting some excess heat away…I have modded all my saws (modestly), and never seemed to loose anything wether using a long or short bar….

Of course if you start making huge ports and/or multiple ports you would start changing things…

 

[tree monkey]

The ports u add are the same size when u do one or two?
@tree monkey

yes