Ported chainsaws.

[Stubby]

11 minutes ago, 1664 said:

I've got 4 spud saws ,just do it and enjoy ?

This .

[Rough Hewn]

I've read the porting thread and a mate has modded a couple of saws but didn't really "get it".
Before xmas worked with a chap who had a few spud ported saws.
I didn't know saws could work that fast!
Saving my pennies now.
[emoji106][emoji106][emoji106]

[lux]

Well I'm keen to try. I have a couple of saws I'd like pepped up a bit.
Spud I will send you the details.

[Stihl123]

i tossed and turned about getting my 660 done.. just thought stuff it and got it done.  now i wish i did it months ago 

did my little 135 myself  and i actually now pick it up before my 560 for anything upto 6" 

so just get it done 

[bmp01]

21 hours ago, Woodworks said:

What are emissions like on ported saws? It's another aspect to safety that I presume porting bypasses. 

Emissions are worse, assuming all other running conditions are the same. ...

 

Fundamentally, the manufacturers were forced by legislation to improve on emissions - so the first thing they did was to make the exit hole in the exhaust smaller. That works by increasing the back pressure on the engine,  forcing some of the unburnt fuel and air back into the engine, reduced emissions but also reduced performance. 

So guess what the first step of tuning is ??

Ok,  so thats a very general comment and primarily applies to older generation (pre strato saws) but it is still true to a lesser extent on more modern saws. 

Other aspects of tuning that improve combustion can reduce emissions - as simple as tuning the carb properly or more complicated an increase in compression ratio, spark advance.

Porting changes including port timing - in general will increase gas flow through the engine, most likely to increase emissions .... 

 

I'd wager any one interested in getting more from a saw is also likely to maintain it and keep it running properly which in itself will reduce emissions. ...

[eddystihl]

Spud did only muffer mod my husky s 550 xp and 562 xp , feel the difference, oke bit louder . Sent them too the Netherlands , 562 with oregon chain is a beast.

[Wonkydonkey]

 

 

preproduction saws are made perfect, tested etc and put through the epa. The saws we get are mass produced, as you prolly know these saws have manafacturing tolerances. Which means every saw is slightly different.  You must have seen a really sloppy Friday saw.

just by cleaning these sloppy tolerances up, you can get a better running saw. How many saws  straight out the box  have a goodish squish of 20/25thou, fuel in the squish Is unburnt so the bigger the squish the more wasted fuel.

the timing is another big subject. 

 

and while the guys sorting a few things out, he can add a bit more of his magic,  which will give it a bit more, 

 

cheers ?