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Meteor Cylinder Porting for Holzfforma G372XP

Paul Fithian

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Second tank at 40:1 mix tuned to 13,000 RPM for more cutting
G372XP 13K RPM Tune.jpg

Felt very strong in red oak, then I noticed this after a few slices:
G372XP Decomp valve fail.jpg

Installed the Stihl decomp valve @drf256 sent me a few months ago for a G660 build and kept on cutting. Ordered a new Husqvarna 503 71 53-01 OEM decomp valve.


Excellent throttle response, new discharge hole and deflector on top of the muffler do a good job of pushing exhaust away from the operator
G372XP Muffler Side View.jpg


This is a strong saw that handles very well.
 
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MG porting

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Ok iv got some more pics to share squish was taken from both transfer sides of the cylinder I never check from front to back always from the transfer sides I can't preach enough to get people do it that way a a photo of what I did to the exhaust port nothing special it's not finished I do plan on popping the cylinder off eventually but not needed right now because of my experiment I'm trying out with my lower transfers I did a compression test with very little oil in the cylinder and I mean very little I just put a drop on my finger tip when I put the cylinder on that's it. I'm subtracting 5 PSI from what the gage says because that's how I am ether way she'll pull a 32" bar and chain no problem.IMG_20231011_130530.jpgIMG_20231011_130239.jpgIMG_20231011_142451.jpgIMG_20231011_132232.jpgIMG_20231011_132255.jpg
 

MG porting

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Base gasket was a thick one lol. So with Base gasket it would have been 0.044 that would have been fine if you were running water for fuel. 🤣IMG_20231011_224517.jpg
 

MG porting

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I'm putting two 3/4" pipes on the muffler total length each will be 2-3/4" to start with they will both be placed in the muffler 1-1/4 I will be running spark arrestors have to unfortunately but I don't think there restrictive enough to notice.IMG_20231012_194309.jpg
 

MG porting

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Got the pipes 3/4" there set in the muffler 1-1/4" deep and stick out 1-1/8" I cut of a little bit from what I started with but not to much need some back pressure should have some good bark to it.IMG_20231014_173427.jpg
 

slackinoff

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@MG porting - you mentioned adding some ignition timing to this one. Did you ever do that? I am hopefully going to do that to my clone kit 372 today. I have a feeling it could use a lot just by the way it’s tuning (has an oem carb on it btw). I’ve seen some of these newer 372 clones needing / accepting and improving from a lot of ignition timing advance.
 

MG porting

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@MG porting - you mentioned adding some ignition timing to this one. Did you ever do that? I am hopefully going to do that to my clone kit 372 today. I have a feeling it could use a lot just by the way it’s tuning (has an oem carb on it btw). I’ve seen some of these newer 372 clones needing / accepting and improving from a lot of ignition timing advance.
No have not because of how much compensation mine has right now I'm going to leave the ignition timing alone until I get a few tanks ran through it then I'll go from there if you plan on bumping yours up I recommend starting small steps I wouldn't go half keyway I would go quarter keyway to start then if you think it can take more then go half keyway never go more than half because you never know what you get at the pump these days and if you live in a state like I do elevation can change dramatically so keep that in mind.
 

Outback

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Pshhh. Turn it up until it pulls the rope out your hand or you hear some detonation. Then back it down a tad. Also perhaps consider an oem decomp for reasons. These are Chinese saws right.
 

slackinoff

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No have not because of how much compensation mine has right now I'm going to leave the ignition timing alone until I get a few tanks ran through it then I'll go from there if you plan on bumping yours up I recommend starting small steps I wouldn't go half keyway I would go quarter keyway to start then if you think it can take more then go half keyway never go more than half because you never know what you get at the pump these days and if you live in a state like I do elevation can change dramatically so keep that in mind.

Got ya - I've gone over halfway on several other saws because they needed it. Not trying to argue, just saying.

Pshhh. Turn it up until it pulls the rope out your hand or you hear some detonation. Then back it down a tad. Also perhaps consider an oem decomp for reasons. These are Chinese saws right.

That's actually my plan on this one. ;)
 

huskihl

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Number 11 weave screen flows 56% I believe. Standard spark screen will flow about 30%. If I were screening pipes, I would put at least a couple 3/4” ID tubes in it, if not 1”. And not very long ones at that. The longer they are, the more restrictive they are
 

MG porting

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Number 11 weave screen flows 56% I believe. Standard spark screen will flow about 30%. If I were screening pipes, I would put at least a couple 3/4” ID tubes in it, if not 1”. And not very long ones at that. The longer they are, the more restrictive they are
I put 3/4 on mine way bigger than the small single one that was in it I plan on using screens off a couple 066 I had I still have new screens from them I believe the route I took will work just fine for felling trees and bucking fire wood like I have said many times before about other saws iv built if it can't pull a 32" then I'll be making changes to it. Lol
 

MG porting

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Got ya - I've gone over halfway on several other saws because they needed it. Not trying to argue, just saying.



That's actually my plan on this one. ;)
Well did you get the flywheel advanced yet?? Let you know a secret I did a half key on mine.😆 Lol.
 

qurotro

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How to advance the timming on the 372?? I can’t find a way to shave the key in the flywheel.
 

MG porting

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How to advance the timming on the 372?? I can’t find a way to shave the key in the flywheel.
If you're using OEM flywheel it's a little bit of work but can be done with a small file and holding the flywheel with the cooling fins facing twords you you need to file the left side of the fixed key of the flywheel.
 
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