Part One: The Exhaust Port

[Mastermind]

When I first became interested in porting saws I would have loved to see a series of threads dedicated to each port and the effects modifications can have on it. A lot of what I've learned came from guys on these forums like @tree monkey @Stihlbro @blsnelling @wigglesworth @Four Paws @David Young and others. I've also learned a lot from some relatively young members too. @Deets066 @Canadian farm boy @drf256 @Chainsaw Jim all come to mind. I'm sure I'm leaving some folks out......and I assure you it's not on propose.

Another more costly way to learn is simply trial and error......and I've had plenty of that too. I've suffered with an overly large ego.......I've been bullheaded......and I've been wrong. I also learned from those things.

Maybe this series of threads can save our members a little of the trouble I've had to go thru to learn.

Now.......keep in mind that there are many ways to achieve excellent results. Take away from this what you need, and leave the rest.

So......for the first part of this series:

The Exhaust Port......

 

[Mastermind]

I'm gonna kick back and get a little work done on some saws while this thread gets some views. Think about what we want to discuss here. Are there any "magic" numbers? How wide should the port be? Shape? Outlet size? Muffler matching?

 

[spencerpaving]

Dirty pics of the exhaust port?....

 

[Mastermind]

Dirty pics of the exhaust port?....

God I hope not.

 

[force10powertools]

I already love this thread...

Sent from my E5823 using Tapatalk

 

[Manofstihl661]

God I hope not.

I think he meant a dirty pic of the saw exhaust port...not your exhaust port [emoji23]

 

[Mastermind]

Wiggs and I used to spend hours talking about this stuff. We could bounce ideas around........then actually test them. These conversations were where I gained to most solid information I have.

Exhaust height?

Low makes more torque? High makes more RPM?

Or not so simple?

 

[blsnelling]

Exhaust height?

Low makes more torque? High makes more RPM?

Or not so simple?

I've found that it's not that simple. I've raised an exhaust before and had a saw loose RPMs.

I've also found that smaller saws seem to require a lower exhaust port than a larger saw. That's kind of contrary to what I would have thought.

Your mileage may vary!

 

[TreeLife]

Sub'd!

 

[Stihlsmoking]

This ...^^^

 

[merc_man]

Im here for the info.
Subbed

Sent from my SM-J320W8 using Tapatalk

 

[merc_man]

I think it would help if someone was able to put a vid togeather from start to finish. That way we could see how numbers are found and what stuff means.
Im not so book smart but more hands on smart.( so i keep telling myself)

Sent from my SM-J320W8 using Tapatalk

 

[Mastermind]

I've found that it's not that simple. I've raised an exhaust before and had a saw loose RPMs.

I've also found that smaller saws seem to require a lower exhaust port than a larger saw. That's kind of contrary to what I would have thought.

Your mileage may vary!

Using what Andre was doing on the 346XP that beat all of our asses at Wigg's GTG several years ago........and the heights of some of my stronger running 90cc saws, I arrived at a EX height to CC scale sorta thing.

Now......there are exceptions, so remember this ain't "the gospel". lol

50cc - 105°
60cc - 103°
70cc - 101°
90cc - 100°
120cc - 98°

The biggest exceptions to this "rule" for me are the stroker or over square type engines. They get "different".

 

[Mastermind]

I think it would help if someone was able to put a vid togeather from start to finish. That way we could see how numbers are found and what stuff means.
Im not so book smart but more hands on smart.( so i keep telling myself)

Sent from my SM-J320W8 using Tapatalk

Here are a couple of videos that might help a little.

 

[t4driller]

Thank you for taking the time to do this Randy!!!! Subscribed

Sent from my SM-G930V using Tapatalk

 

[Deets066]

Dirty pics of the exhaust port?....

 

[Deets066]

Step one for me

Gettin rid of the dirty exhaust port

 

[Mastermind]

Glad you're here Deets.

Some of the stuff I see you doing is very interesting. I'm hoping to see this turn into a learning experience for us all.

 

[Stump Shot]

Liking this thread already, having just "ported" my first saw, all I was able to do was widen the intake a little, the exhaust a little bit more and deepen and smooth the transfers. The exhaust was a main focus, polished and port matched with a modified muffler, advancing the timing, set squish and piston mods pretty much wrapped it up. Not knowing where to begin with the numbers, I never even tried to degree the saw, as they did not mean much at the time. Having a basic guide will be a monumental step forward if I'm ever to make a true ported saw and not just one that's been dickered with. Surely had I been armed with a basic target guide for the numbers this saw may have turned out different. I'm hoping I'm at least on the right track, what do you fellas think?
Here's my first attempt at porting - Husqvarna 51 open port .325" - 20" bar 16" Norway Pine log.

Oh, and for the record, you guys are definitely wearing off on me!

 

[kkemp]

Great thread already . Maybe I can get some ideas for the 028 super jug my dealer gave me Saturday.