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stihl 440 porting beginner

brb89

brb89

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Hi folks. New to the site, not new to saws. I currently have a couple of 440’s in rebuild process and would like to do moderate port job to at least one of them. Worked in precision machine trade for a number of years so I’m comfortable with a pencil grinder, just not overly familiar with measurements and appropriate approach to see some moderate gains without compromising reliability. There are some old posts that I can find but if they had pictures, I can’t see them anymore. I really think that the pictures can support an explanation significantly so I’m hoping someone has the willingness to share insight, tips, pictures, etc.

Thanks guys
 
pioneerguy600

pioneerguy600

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Sorry, all those pics went away and I didn`t back them up, lost close to 2,000 pics to photobucket shortly after this site was hacked.
 
pioneerguy600

pioneerguy600

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Many of the members on here had many different threads posted with explanations and pics, everything from carb rebuilds, case splitting and bearing replacement to porting threads were all lost to future users after the site was hacked. Untold info went down the drain, especially all the pics.
 
brb89

brb89

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Many of the members on here had many different threads posted with explanations and pics, everything from carb rebuilds, case splitting and bearing replacement to porting threads were all lost to future users after the site was hacked. Untold info went down the drain, especially all the pics.
What a shame..well hopefully someone out there has some fresh content they are willing to share
 
Brownthumb

Brownthumb

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I found enough information on this site to port and also raise my transfers on my hutzl 440.
I forget the numbers.
It ran pretty good but vibrated like crazy and would not idle well.
I bought a hutzl 460 cylinder and went at that with the grinder after searching this site and putting working numbers together.
I forget what I came up with.
She ran like a raped ape. Until. image.jpg
Get some cheap hutzl cylinders or used ones to test out and try and practice on. I am a machinist also per say.
I chucked the ported 440 p&c back on her and after the muffler mods and timing advance I did for the 460 head this 440 runs very well, idles nice and the vibration is almost gone.
 
pioneerguy600

pioneerguy600

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There is lots of info on here but it seems the lack of pics has become more of an issue. I ported 044`s for about a 10 year span and now those saws are considered old, close to vintage so not many guys porting them right now.Thus the lack of pics or porting threads on them at this time.
 
drf255

drf255

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You’ll not see much gain from just opening the ports. You may make things worse.

They do quite well with a little flattening and sanding of the squishband and then turning the base down on the lathe to a squish of 20.

Uncork the muffler and advance the timing around .025 off the key.

You’ll be quite happy.

For anymore gains, the majority of them come from machine work and altering the port timing. Just hogging out the ports generally results in a saw with less throttle response and a narrower power band. Less is really more with the factory OEM jugs, especially the coveted slant fin.
 
pioneerguy600

pioneerguy600

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There is not much one can remove from the ports on an 044 as in widen them due to the piston skirt is fairly narrow and only covers the port on either side by a narrow margin but opening the exhaust side maybe 1/16 on each side and re blending the top and bottom of the port is ok . One needs to trace the port shape on the piston first though as the port can be offset from dead center leaving less cover on one side than the other. Plenty of careful planning is needed and lines laid out before grinding begins, if one does not then it don`t take much to ruin a cylinder. I had a basket full of ruined cylinders sent to me by over anxious guys that tried to skip the layout part and ground too far and opened up a gap on one side or another, some were free porting, others too wide for the piston skirt to cover, ring ends exposed to a port etc. I found that just grinding the ports to a set of numbers does not guarantee a hot result, its all the other little things done to the whole system that creates a stronger engine. I still run 7 of my 044`s when cutting big hardwood, if its big enough then the hybrids get a turn also.
 
brb89

brb89

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There is not much one can remove from the ports on an 044 as in widen them due to the piston skirt is fairly narrow and only covers the port on either side by a narrow margin but opening the exhaust side maybe 1/16 on each side and re blending the top and bottom of the port is ok . One needs to trace the port shape on the piston first though as the port can be offset from dead center leaving less cover on one side than the other. Plenty of careful planning is needed and lines laid out before grinding begins, if one does not then it don`t take much to ruin a cylinder. I had a basket full of ruined cylinders sent to me by over anxious guys that tried to skip the layout part and ground too far and opened up a gap on one side or another, some were free porting, others too wide for the piston skirt to cover, ring ends exposed to a port etc. I found that just grinding the ports to a set of numbers does not guarantee a hot result, its all the other little things done to the whole system that creates a stronger engine. I still run 7 of my 044`s when cutting big hardwood, if its big enough then the hybrids get a turn also.
Thanks for the reply. If I were to more or less stay away from porting, what other things can be done to the whole system?
 
pioneerguy600

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It`s kind of a package so I found but if you think of the basics of getting more air through the carb, that picks up more fuel from the venturi and how that mix gets to the crankcase, then up through the transfers to the top end, above the piston on the compression stroke is step one for me. Next its compression and spark creates the explosion that drives the piston down til the exhaust port opens and the exhaust port gases are spent, the upper transfers open and allow fresh mix to be pushed into the cylinder helping to push the last of the spent charge, exhaust , out the port. Many small steps are there that can be improved, some judicious port shaping, grinding required , and many small changes to the support system can be made.
Back to step one, intake of air, run a less restrictive air filter, bore the carb if possible, remove the choke assembly and install a primer setup all allows more air through the carb, feather the throttle shaft and plate. Grinding and shaping the intake port, grinding and shaping the upper transfers and the transfer tunnels themselves, directing the incoming charge back toward the intake side of the cylinder helps scavenge the spent exhaust gases and helps keep more of the incoming charge in the cylinder, not escaping through the still open exhaust port. Next it helps to tighten down the squish gap between the piston and cylinder head, remove the base gasket and seal the cylinder base to the crankcase raises compression , seal it with a suitable sealer. Always open to conjecture as to what sealant is best, never had a problem ever with any I have used. Next step is to open the exhaust some and reshape the exhaust port, how much depends on the width of the piston skirt or a percentage of the cylinder bore. Once the exhaust port is opened then the muffler exhaust flange needs to be opened just a hair larger than the port so no restriction is blocking the exhaust path, the muffler internals need to be accessed, remove restrictions inside the muffler, create a larger exhaust port in the muffler to the outside or create a second port, size depending on the extent of port work that has been done. I am not personally a believer of the 80% theory, often go more open but its a personal thing, go as big or small as you like. Next a small advance in the timing works well on most chainsaws, not all but its worth a shot, taking .020 off the woodruff on the crank key allows the flywheel to advance timing a few degrees, usually a safe bet but in some instances the engine will kick back excessively when trying to start it or another problem arises where the engine will not slow down as quickly as it should causing over run when the throttle trigger is released. . One will know when either of these symptoms occur and the flywheel adjusted. put back to original location is easy enough.
Other things like carb tuning, making sure fuel delivery is not restricted, good fuel lines, tank filter in new shape , small stuff all adds up to a good running saw. Things can be taken further but requires more work and more parts replaced or modified. Take this as an overview and not an actual blueprint, the study and improvements are an ever evolving thing/study and the basics is just a start into the craziness of engine porting that can ensue.
 
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