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Meteor Cylinder Porting for Holzfforma G372XP

Paul Fithian

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Figured I start with a 1/2" hole reamed out a bit with a file to start with. I can make this bigger later if needed.
 

Paul Fithian

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Meteor P/C kit arrived and I was able to take some measurements:. Cylinder looks very nice, don't think the intake or exhaust ports should go any wider. Plan to adjust transfer and intake to targets without a base gasket.
Meteor PC Timing.jpg
Bottom of cylinder matches gasket pretty closely, I'll grind away black marked sections and smooth out other areas in this passageway
Meteor 372 Cylinder bottom stock.jpg
Meteor 372 Exhaust.jpg
Meteor 372 Intake.jpg
Meteor 372 Transfer 120 Deg.jpg
 

MG porting

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I just ordered my f372w this morning I plan on tearing it down and looking it over and port the cylinder and fab up a new muffler to start later I'm going to split the case and change out the crank and put a Hyway piston and cylinder on it the meteor cylinders are very nice but but very expensive, if I was you put the piston in place and stick a ring in the cylinder and place the cylinder on and see where the ring ends at without the base gasket and see if you even have to move the upper transfers at all.😎
 

Paul Fithian

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Measurements were taken with ring on top of piston & base gasket removed. This Meteor cylinder and piston look to be of much higher quality than the P/C this saw was built with.

I'll use the Holzfforma jug to practice porting on transfers and to see if taking it down to 120 degrees breaks through the tunnel wall. I may run it if it doesn't.
 

srcarr52

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Measurements were taken with ring on top of piston & base gasket removed. This Meteor cylinder and piston look to be of much higher quality than the P/C this saw was built with.

I'll use the Holzfforma jug to practice porting on transfers and to see if taking it down to 120 degrees breaks through the tunnel wall. I may run it if it doesn't.

I'd be careful when porting it. The meteor brand cylinders have really hard plating that is prone to flaking.
 

Paul Fithian

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Thanks Shaun, I've read that posted by others as well.

What can you suggest to prevent such flaking with a Meteor? Or would it be better to leave it as is?
 

srcarr52

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Thanks Shaun, I've read that posted by others as well.

What can you suggest to prevent such flaking with a Meteor? Or would it be better to leave it as is?

Some have luck with grinding the plating away before going at the port with a carbide burr so they don't lift the plating when removing the port material.

Personally I would stick with the cylinder that came on the saw, I haven't run into any problems with the plating flaking on them.
 

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Some have luck with grinding the plating away before going at the port with a carbide burr so they don't lift the plating when removing the port material.

Personally I would stick with the cylinder that came on the saw, I haven't run into any problems with the plating flaking on them.
I'm with Shaun on this one. If a person spends the extra money to buy a Meteor or Hyway cylinder, then I would leave the ports alone and hope for the best. I have ported several farmertec jugs with good success.
 

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Port edges are best done with diamond burrs on Hyway and Meteor. Once you grind through the chamfer (the worst spot for plating lift) a sharp carbide will usually cut pretty well but you have to be careful not to grind into the bore. Always grind into the port. I’ve wrecked several Hyway jugs at the corners of the transfer uppers. Now I do all the plating edge with diamond. It’s slow but I’m not good enough to keep the burr rotation lifting into the port. It really sucks to be on the last upper and then flake the plating.
 

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I’m with the others here Paul.

Meteors lack the finesse of the OEM. Their plating is like Kryptonite and their bores concentric.

They will run, albeit poorly, for a long time.

I machined and ported all of one meteor jug, and never again. Destroyed a few cutters and burrs in the process.

Id use a diamond ball/burr to get down to the aluminum and then finish the ports with a regular burr. Make any small adjustments with diamond burrs.
 

Paul Fithian

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Porting done on Meteor cylinder, plan is to run this cylinder going forward unless it fails. Nothing touched near the plating, port heights remain where Meteor put them.
IMG_3396.jpeg
IMG_3397.jpegIMG_3399.jpegIMG_3401.jpeg
IMG_3400.jpeg
 
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MG porting

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My saw showed up today got it all torn down here's a few pictures I took tomorrow I'll be doing some port work mostly clean up big time.IMG_20231009_204354.jpgIMG_20231009_205220.jpgIMG_20231009_204727.jpgIMG_20231009_204418.jpgIMG_20231009_210111.jpg
 

MG porting

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Now I'm not sure if anyone has ever noticed or just never say anything about it but the cylinder base gasket protrudes a 1/8 into the lower transfer tunnels that alone is a power robbing bottle neck I do plan on doing a base gasket delete a open up the lower transfers a bit and clean the tunnels up nothing crazy there uppers I'll leave for now until I run the saw for a few weeks then I'll put my timing wheel on the saw and go from there they did run the saw before it left the factory glad they didn't run it to long with all the ruff edging but still feel good about the saw pretty well put together everything was nice and tight has pretty good comparison I'll put a compression gauge on it after tomorrow and get numbers for everyone I'm guessing without base gasket it should at least be 150psi or 160psi I'd be pretty surprised if it had more than that.
 

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Now I'm not sure if anyone has ever noticed or just never say anything about it but the cylinder base gasket protrudes a 1/8 into the lower transfer tunnels that alone is a power robbing bottle neck I do plan on doing a base gasket delete a open up the lower transfers a bit and clean the tunnels up nothing crazy there uppers I'll leave for now until I run the saw for a few weeks then I'll put my timing wheel on the saw and go from there they did run the saw before it left the factory glad they didn't run it to long with all the ruff edging but still feel good about the saw pretty well put together everything was nice and tight has pretty good comparison I'll put a compression gauge on it after tomorrow and get numbers for everyone I'm guessing without base gasket it should at least be 150psi or 160psi I'd be pretty surprised if it had more than that.

It's not only the gasket, but I've found that the case is never the size of the lower transfers, especially with the BB cylinders.
 

MG porting

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It's not only the gasket, but I've found that the case is never the size of the lower transfers, especially with the BB cylinders.
The aliment is pretty good with mine some what the gasket is about the same on the case as the cylinder im going out to the shed here in a few and start working on the ports I'm also thinking about popping the flywheel off and advancing that to something that I've always had to do with Stihl saws.
 

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Happy to report this saw runs perfect. Tuned to ~ 12,000 RPM for break in with 24:1 mix, excellent throttle response in both directions. Drops to ~ 8,000 RPM cutting red oak with a 24" bar and Oregon 73EXL PowerCut chain

New Husqvarna piston pin bearing installed:
Husqvarna Piston Bearing.jpg

Final assembly was with a 0.003" paper gasket and Motoseal both sides, squish ended up at 0.037"
G372XP Paper gasket-motoseal.jpg
G372XP Assembled Squish.jpg
G372XP First Cuts.jpg

G372XP Clutch Side on bench.jpg

Several teachable moments with this saw build.
 
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MG porting

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@MG porting , what were your timing numbers on this saw as as built and how you received it?
I did not check timing numbers before I tore it down I didn't care there all pretty close to the same Im putting it back together I forgot to take pictures before I stuck the cylinder back on my brain was pre occupied of all the stuff I had to do do to get the intake and tank handled to get along with each other but don't worry all I did to the intake and exhaust ports was get rid of the ugly that was it on those I did open out the lower transfers but how I did mine is completely different from everyone else so not showing those to anyone just yet the base gasket is out and will never going back these things suck for squish if I get a brake today from everything else I'll try and at least post som mor pics of squish and exhaust port and compression sorry ago for not having mor details on timing numbers I will put my timing flywheel on it but that will be later on after I've ran a few tanks through it.
 
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