This seemed the best area to ask since it's not a tool question so much as an engine question, I use a high-end premade fuel and always have a sharp or sharp-ish chain, am just hoping to learn the basics about modifying 2-stroke engines like this (am only interested in chainsaws specifically but imagine it's applicable to all 2-strokes), I've heard someone mention they "had their saw ported", although at the same time porting is just boosting displacement adn that's not an automatic HP gain (if I understand things correctly...they're linear for sure, just not perfectly-so)

Anything from porting to fuel to exhaust to idle-speed would be greatly appreciated, I've got a very small top-handled unit that I'd like to try and "tweak" as much as possible (25cc's pushing barely over 1hp), am ok spending real $ on this if necessary (within reason of course, not looking to rebuild a tool just 'hotrod one') I also found larger aftermarket dogs/bucking spikes/whatever you like calling them, to be very useful for anyone trying to move fast (I know I know, inherently unsafe, at the end of the day it's always a balance beam to walk properly which is why if modifying a saw makes it 5 or 10% more powerful and effective then I'd be all over it!

  • No substitute for cc's - had an old Danarm 90cc that just would not stop even on sticky pine...
    – Solar Mike
    Jun 16, 2019 at 8:15

1 Answer 1


The absolute key to more power on a small two-stroke is the exhaust. Designed properly, it will scavenge well and improve the engine's volumetric efficiency. Special exhaust was Mr. Stihl's rise to fame if I recall.

However, designing this stuff is for serious engineers with a lot of magic knowledge. There may be some bolt-on parts out there to help you.

There's a lot of folks "hotrodding" chainsaws; you can probably get some general inspiration from forums on the internet.

  • Thanks a lot!! I've been googling and youtubing a bit on this subject, I feel it's fair to be forgiven for thinking almost-any chainsaw can be 'boosted' simply by 'porting' (ie drilling or burring-out) the muffler's final-exhaust-port a bit (the oh-so-common 'muffler mod'), I guess it's something where I'd have thought that opening-up the muffler's exhaust would ONLY help if&when you'd already changed the output of the engine (so it'd be done if you were porting the block's intake/exhaust ports or something, yet I am very frequently seeing it done on its own which I just don't get) Jun 27, 2019 at 20:31
  • (hit submit by accident - also am OP, am worried this may be a different username) I also wanted to ask if it's appropriate to go grab a cheap tachometer (laser/photo type) online, can get them for like $15 all day on ebay, from how I understand it this is basically a requisite tool for both properly-tuning (well, 'tuning to max-power' w/o mods) a saw as well as dialing in a tuned saw (especially so, here, I would think!) Should clarify that I'm just trying to get an understanding & not trying to do a project now, am still dialing-in my sharpening game!! :) Jun 27, 2019 at 20:36

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