Stihl 038 magnum for Andrew... What do they like?

[NateSaw]

For my best buddy... I've posted around looking for oem... He's ready to have the saw back... Originally this was an av. He bought it at auction and didn't know someone spun the bearings and ate the case. He found a good used case from ebay, but it wasn't listed as a magnum. It's a magnum. So... For his birthday, I bought a hyway top end. I know... I know... But that's what it's getting... . I intend the usual suspects, base gasket delete, somewhere around 20k squish, already ripped the baffle out of the muffler, will likely treat the airbox as I did the 026, file the keyway at least 18k for advance... I'm not likley to touch the lowers... Yadda yadda... I want to apply what I've learned from you guys here... But I haven't a ballpark. I recieved the topend from hl supply, but I'm waiting for a response for return because the squish has such horrible cast voids, I just can't use it. This is the third hyway cylinder I've had in my possession, but the first to have casting voids. Long story short, I don't have base numbers yet... Thoughts from my mentors?

 

[NateSaw]

The case he received is in nice shape. Wasn't used hard. Seals and bearings are perfect.

 

[Mastermind]

For my best buddy... I've posted around looking for oem... He's ready to have the saw back... Originally this was an av. He bought it at auction and didn't know someone spun the bearings and ate the case. He found a good used case from ebay, but it wasn't listed as a magnum. It's a magnum. So... For his birthday, I bought a hyway top end. I know... I know... But that's what it's getting... . I intend the usual suspects, base gasket delete, somewhere around 20k squish, already ripped the baffle out of the muffler, will likely treat the airbox as I did the 026, file the keyway at least 18k for advance... I'm not likley to touch the lowers... Yadda yadda... I want to apply what I've learned from you guys here... But I haven't a ballpark. I recieved the topend from hl supply, but I'm waiting for a response for return because the squish has such horrible cast voids, I just can't use it. This is the third hyway cylinder I've had in my possession, but the first to have casting voids. Long story short, I don't have base numbers yet... Thoughts from my mentors? View attachment 374094

Straight from the hip without looking at my notes....

.040 outta the squish.
Ex: 102
Tr: 118
In: 76

 

[NateSaw]

Straight from the hip without looking at my notes....

.040 outta the squish.
Ex: 102
Tr: 118
In: 76

Somewhere in the hood of 030 off base... To land at roughly 020 squish... Sounds like you did 1 or 150 of these lol. Thanks Randy.

 

[NateSaw]

@Mastermind, @drf256, @Rich Fife, @huskihl, when you guys lay out for exh port widening... What's max width? 1mm from skirt edge? Also, in leu of bigger not always being better... What's the determining factor here? Is there a point where you can have too little back pressure?

 

[huskihl]

@Mastermind, @drf256, @Rich Fife, @huskihl, when you guys lay out for exh port widening... What's max width? 1mm from skirt edge? Also, in leu of bigger not always being better... What's the determining factor here? Is there a point where you can have too little back pressure?

1.5mm from the skirt up to 65%. But depends on how it runs compared to the height of the exhaust port

 

[Mastermind]

Like Kevin said.

 

[Rich Fife]

I dislike the metric system sooooo it's .050" for me.
I too try to stay around the 65% "rule"...
But, I tend to do stupid *s-word and I'm honestly nobody to asked detailed questions... as I've been playing with saws for 1yr and I still feel as if I just started. Seems like when I think I know something indepth... I find out that the little bit that I thought I knew... was only a fraction and i didnt know it all that good. And dammit, its that exact *s-word that continues to draw me in deeper to learn more, to make more power and to try new things... these saws are very addictive... rewarding... and at times, very disappointing.

 

[Mastermind]

I dislike the metric system sooooo it's .050" for me.
I too try to stay around the 65% "rule"...
But, I tend to do stupid *s-word and I'm honestly nobody to asked detailed questions... as I've been playing with saws for 1yr and I still feel as if I just started. Seems like when I think I know something indepth... I find out that the little bit that I thought I knew... was only a fraction and i didnt know it all that good. And dammit, its that *s-word continues to draw me to learn more, to make more power and to try new things... these saws are very addictive... rewarding... and at times, very disappointing.

I really like this post Rich.

 

[Rich Fife]

I really like this post Rich.

Thank you good sir. Just giving an honest response.

 

[Al Smith]

If memory serves it was 52 or so stock piston /head deck so it would be about 30 off the base .Mine has a cut dome piston and sweeps on the transfers .Stock it was around 102 on the exhaust which I raised up to I think 96 .It will dead stick at around 14,500 RPM . I run an 8 tooth rim but it might do better wih a 7 . I really should keep better notes plus remember where they are .So far all I've been successful at is lists of what parts fit if you can't find OEM .

 

[NateSaw]

I imagine y'all mean 65 percent of the skirt width? Also, from my limited machining experience, I too am always taking the metric x 25.4 lol.

 

[thompsoncustom]

1.5mm from the skirt up to 65%. But depends on how it runs compared to the height of the exhaust port

is that the same for the intake side?

I imagine y'all mean 65 percent of the skirt width? Also, from my limited machining experience, I too am always taking the metric x 25.4 lol.

65% of the bore width

 

[Al Smith]

Obviously everybody on this forum has a computor else you wouldn't be here .Do a Google on "convert " which is a downloadable thing that will convert about everything from inch to metric etc .Takes the guess work out of it .Handy as a pocket on a shirt .

 

[NateSaw]

Obviously everybody on this forum has a computor else you wouldn't be here .Do a Google on "convert " which is a downloadable thing that will convert about everything from inch to metric etc .Takes the guess work out of it .Handy as a pocket on a shirt .

No guessing here.
Mm/25.4 or,
Inch x 25.4
I have the app... It's the calculator! Lol.
For everything else, I use convertpad app.

 

[Rich Fife]

Takes the guess work out of it .Handy as a pocket on a shirt .

Not too sure where the guess work is on the metric to imperial conversions but, i can definitely say I can't stand shirts with pockets.

 

[NateSaw]

is that the same for the intake side?

I believe the ring gaps play a critical role on the intake port. I think staying within them is advisable to avoid catching a ring.... Sound right fellers?

 

[NateSaw]

Depending on the saw....

 

[NateSaw]

On this 044... Wtf finishes out the tank breather? What the dealer gave me, is either incomplete, or not for this saw.
This is my temporary solution... A nipple cap with a slit cut in the top. Works, but leaks a bit.

I'd love to know, and have what belongs on this saw... Any guidance would be appreciated as usual.

 

[Mastermind]

On this 044... Wtf finishes out the tank breather? What the dealer gave me, is either incomplete, or not for this saw. View attachment 374782
This is my temporary solution... A nipple cap with a slit cut in the top. Works, but leaks a bit.
View attachment 374783
I'd love to know, and have what belongs on this saw... Any guidance would be appreciated as usual.

Inside the tank is an umbrella seal. On top of that nipple a short hose fits and goes into that loop just ahead of the fitting.