I am new to modding saws and like the title says i have a 5100 and i am looking for basically the top 3 mods i can do to it to make it even more impressive. I run a 3/8 chain 18 and 20 inch on it. Mostly the 18 is on though. I dont want to lose longevity but i would like to pep it up. My buddy sure does brag up his 361 and since there is not a dolmar 5900 i would like to just make this one a little closer to his in speed and power.
If your running a 3/8 .050 chain on you saw buy your self a couple of square ground chains from bailey's. They are a site sponsor here. I have heard that alone is good for up to 20% increase in cutting speed. Do a muffler mod to your saw. Do a search for muffler mods on this site. There are so many you could just about write a book on the subject. This will help your saw run alot cooler and increase horsepower. I would do these two things and see how your improved saw compares with your buddies 361. If thats not enough you will have to get into some mild porting to get more power. there are lots of things written on doing woods porting here and do a search and start reading. Good luck Rick!
Like Rick Rock said, go with square ground as #1. I still haven't purchased one though
#2 If you cut with the 5100 in Winter time, which I'm sure you do from the likes of where you live, I would not recommend this mod as the saw needs the heat from the engine in low temperature (below 40º F) to prevent carburetor icing. But, If you primarily use the saw during warm weather, then I would recommend this simple muffler mod. And that is to remove the heat transfer shield that is inside the exhaust deflector. If you can weld, cap the back of the deflector while you're at it and with a screwdriver, raise the roof of the exhaust deflector to a round shape, instead of the flat shape it has. Just letting the engine breath a little more. If you are willing too, enlarge the exhaust hole. Don't go hog wild on this though. The engine needs backpressure for the torque that this little monster produces.
#3 If you are mechanically inclined and want to challenge yourself a little bit, lower the squish to .020
I would leave the ports alone as they are tiny. Especially the exhaust port. No room for error whatsoever. So be careful. (Just a side note, on my 5100, I lowered the intake some degrees for a slightly bigger charge)
