OK Guys...I finally decided to ask. I see that some have decided to modify their saws. I guess I somewhat understand the reasoning, more power from a smaller lighter saw. Muffler mods are easy to figure out. Kind of like puttin' headers on the old chevy to reduce exhaust restriction. What exactly happens when you port a saw? More compression? Also, what effect does this have on the life-span of the engine?
The jist of it: increase compression, increase ports to maximize more air in and more air out. an engine is a nothing more than an air pump. The more air/fuel you can get it, the more power it will make and the more efficient it will be. The added compression maximizes the increased volume of air/fuel and the exhaust needs to be opened up to get the air out faster. the issues lie in the port timing, just because you hog out the intake and exhaust, don't mean it will run better... too much compression can cause detonation. transfer port timing raised too much will kill a saws power band and make it peaky, as well as increasing the exhaust duration and intake duration. Duration is the amount of time the intake or exhaust is open to either let in air in, or air out. I've ruined a lot of jugs just trying to make a saw run better, hogging out a huge intake port, or exhaust port will not make it run good, everything has to be in sync with where the piston is at in relation to TDC, BDC, etc. as far as longevity, as long as things are kept within reason, durabity can be increased. added compression won't always raise temps if the exhaust is set right to expell the spent gases out faster. Too much compression can beat the crank bearings out over time, as well as increased wear on starter components. Too square of edges on ports can cause rings to snag or marks on the piston.
Thanks for the explanation. Being strictly a firewood guy, if I felt my saw was "under-powered" for the task...I brought the bigger saw.
Lots of strictly firewood guys here with ported saws... once you run a ported saw, its addictive... a ported saw will run better, have less weight than the next size up saw. i have one stock saw...its my 550xp... it screams with a muffler mod only.
Does a porting a saw effect its longevity? About all racing engines run great for a while, but short lived
if done right, no. Might actually last longer. as it will run cooler. if done wrong, it could shorten its life. Race saws make three cuts and can't be run more due to the heat built up.. There is a fine line between the race saw and hot hot work saw...
Higher power = higher thermal loading of engine components. Higher BMEP = more pressure/heat in cylinder and that equates to more ring wear and load on engine bearings. etc.
I very much interested in modification of moto saws. Here in Germany it is not common, most unheard of.
Here is a one of my threads where I show pics of a muffler mod Guntar. You might like it. Good to see more people from across the pond joining our site! http://firewoodhoardersclub.com/forums/threads/new-cs590-timber-wolf-is-in-review.6077/ Ok back on topic sorry op..
It's better than my Deutsch! It's always amazed me how many folks from elsewhere in the world speak English, but most Americans can barely speak English, let alone a foreign language... Welcome
Is it worth the time and hassle to "port match" the intake and exhaust? Always wanted to do that to my old husky 350 but it's so reliable I don't want to fubar it
It's usually worth a look. Some saws are terrible in this department, others have little room for improvement.
I've always wondered what the "average" woods port runs? I guess I'm trying to do a cost benefit analysis. I always muffler mod my stuff after the warranty runs out. Does seem to add a lot of power.
