390xp Muffler Mod. Also: Compression readings on 346 and 372.

[rngrchad]

Spent the evening doing a muffler mod on my 390xp. I still have to paint it and tune it. Doing that tommorow. Also did a muffler mod on an 025 but that's for another thread someday. Anyhow, here's how the muffler mod went down with a few pictures. She sure sounds good. Brazed it with MAP GAS and Oxygen using a Bernzomatic Torch. My initial mod used copper tubing as I thought it would braze easier, but I had alot of problems getting the copper to take the brazing material. Long story short, I ditched the crappy copper, found some 3/4" conduit to use and the brazing went way easier. It seemed much more difficult this time around compared to when I did my 372. Dunno why? Dirtier metal maybe? Anyhow here's a few pictures. Enjoy!

And those who didn't see the 372 here's the link to that:

Also thought I would throw this in, as I read alot of questions about compression numbers on saws.
My 372's compression readings:

My 346's Compression readings:

My 390's compression readings:
Didn't get the picture to work....

 

[orbound]

Question

What do you gain with that setup? Does that shorten the saw's life any? Oh, and if you happen to know, what can a guy do with smaller saws (55cc and less) to hop them up a little and still get good life out of the saw?

 

[pbtree]

I am interested in details after you run it for a bit - I have not had the time to fool around with my 390 muffler just yet, but I love the saw and intend to do so - maybe your experience will inspire me!

 

[rngrchad]

I am interested in details after you run it for a bit - I have not had the time to fool around with my 390 muffler just yet, but I love the saw and intend to do so - maybe your experience will inspire me!

Pbtree, I will follow up with my experiance of the muffler mod. I read a few people mentioning the 390 responds to mods better than most any other saw and therefore I just couldn't resist getting started opening the exhaust a bit. My 372 really liked its' muffler mod. I imagine this 390 will respond the same if not better. :chainsawguy:

 

[Tree Sling'r]

Pbtree, I will follow up with my experiance of the muffler mod. I read a few people mentioning the 390 responds to mods better than most any other saw and therefore I just couldn't resist getting started opening the exhaust a bit. My 372 really liked its' muffler mod. I imagine this 390 will respond the same if not better. :chainsawguy:

I am sure it will help, the but the real 390 gains go much deeper into the cylinder.
Just a word of advice, do with it what you want.
You can order an 288xp exhaust defelector for $13, it bolts on, looks sharp and is never in the way.
#503 07083-01

 

[rngrchad]

I am sure it will help, the but the real 390 gains go much deeper into the cylinder.
Just a word of advice, do with it what you want.
You can order an 288xp exhaust defelector for $13, it bolts on, looks sharp and is never in the way.
#503 07083-01

Thanks for the part# Tree Sling'r. When you mention "deeper into the cylinder" you are referring to cylinder porting and a higher compression piston? I have ported two smaller 50cc stihls a 361 and an 025 just for fun, but I am not savvy to the science behind the correct ways to go about it, and am therefore a bit hesitant to do this to my huskies as I use them all the time and am concerned about reliability. I guess I just need to get on the forum and search out the porting information that I see floating around on AS. Thanks again.

One more thing: Tree Sling'r how does my opening percentage look? I have a lot of room to remove material from beneath the exhaust deflector....almost 1/2" more diameter of material.

 

[Tree Sling'r]

Thanks for the part# Tree Sling'r. When you mention "deeper into the cylinder" you are referring to cylinder porting and a higher compression piston? I have ported two smaller 50cc stihls a 361 and an 025 just for fun, but I am not savvy to the science behind the correct ways to go about it, and am therefore a bit hesitant to do this to my huskies as I use them all the time and am concerned about reliability. I guess I just need to get on the forum and search out the porting information that I see floating around on AS. Thanks again.

By widening the exhaust and intake you will get real good gains. With no skirts on the piston you can widen things out quite a bit. It is safe. Don't mess with the top of the exhaust.
And yes I get really good gains going deeper, with milling and lots of work on the transfers.

 

[Tree Sling'r]

One more thing: Tree Sling'r how does my opening percentage look? I have a lot of room to remove material from beneath the exhaust deflector....almost 1/2" more diameter of material.

I have never measured a hole in my life, I guess it is fine.

 

[rngrchad]

By widening the exhaust and intake you will get real good gains. With no skirts on the piston you can widen things out quite a bit. It is safe. Don't mess with the top of the exhaust.
And yes I get really good gains going deeper, with milling and lots of work on the transfers.

Alright, so your stating to go WIDE and just smooth the tops and bottom's of the intake and exhaust. I hate to sound like a noob (as I am when it comes to porting saws) but how much is typically removed from the sides of the intake and the exhaust? I really want to to do this but for some reason have reservations.

 

[jack-the-ripper]

I am waiting on my 390XP to be sent back to me, after porting, next week. I will get videos on here as soon as possible. It is taking a bit longer than expected, with the builder having health issues. I said I would not do any porting on this saw when I bought it but..........that nasty CAD kept whispering in my ear or is that my schizophrenia?

 

[polexie]

Impressive piece of work, as i understand it , think you will get deeper into the cylinder

Please let us know how it performs in a big piece of lumber.

Thanks for sharing,

Lex

 

[rngrchad]

Impressive piece of work, as i understand it , think you will get deeper into the cylinder

Please let us know how it performs in a big piece of lumber.

Thanks for sharing,

Lex

Sure will Polexie. It's still rather new...still going through break-in. I just couldn't resist it. Only 8 tanks of fuel through her currently. I should get it out here in a few hours. Hopefully I can post back tonight w/ a video or more pictures. Thanks for the kind replies. It sure makes playing with my chainsaws more entertaining knowing people are interested! I love this site.

 

[Tree Sling'r]

Alright, so your stating to go WIDE and just smooth the tops and bottom's of the intake and exhaust. I hate to sound like a noob (as I am when it comes to porting saws) but how much is typically removed from the sides of the intake and the exhaust? I really want to to do this but for some reason have reservations.

Well, it is somewhat complicated. By widening you have to get down to the aluminum and widen, leave the top and bottom alone, but keep the entire port in uniform shape. Polish.
The intake I leave rough, after I work it over, I put a rasp in a drill and get a rough uniform finish with no high or low spots.
Don't mess around with it if you are worried about messing things up. I was never worried and learned from it.

 

[rngrchad]

Well, it is somewhat complicated. By widening you have to get down to the aluminum and widen, leave the top and bottom alone, but keep the entire port in uniform shape. Polish.
The intake I leave rough, after I work it over, I put a rasp in a drill and get a rough uniform finish with no high or low spots.
Don't mess around with it if you are worried about messing things up. I was never worried and learned from it.

Excellent. Thank you for the quick "heads-up" on roughing up the intake. I would have never thought to do that. I will see how satisfied I am with the current muffler mod and go from there. The mild porting I did on my ms360 seemed to really help but I never liked that saw as much as my huskies and therefore wasn't afraid to just go at it so to speak. I will keep your information in mind if and when I go forth w/ a mild port job. Thanks so much, as I know you take saws in and make'm screamers and turn them for profit. I do realize this and do thank you.
-Chad

 

[rngrchad]

Quick Video for AS.

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I don't have any handy dandy log holders so it was kind of awkward trying to cut into that little ASH log. The thing wanted to keep falling over with the saw in it

 

[bookerdog]

I am waiting on my 390XP to be sent back to me, after porting, next week. I will get videos on here as soon as possible. It is taking a bit longer than expected, with the builder having health issues. I said I would not do any porting on this saw when I bought it but..........that nasty CAD kept whispering in my ear or is that my schizophrenia?

Ported 390 just flat out run.:hmm3grin2orange: