0.015" is pretty tight, definitely wouldn't want any less.I have a few things to share that might be helpful.
I was given a pair of Husqvarna 350 chainsaws a few months ago from a kind relative. Both of these saws were used at family cabins and were marginally/non running projects. My tinkering was inspired by the folks in this forum and the consideration that if something catastrophically broke during my maintenance the financial loss would be minimal. I am not a professional repair guy but can turn wrench and hope some of my experience might be helpful for you.
Initially, the first saw had 90psi compression, only 3 of 4 4mm hex head bolts securing the cylinder to the base block and only 1 of these small bolts was tight. This saw did not run.
Upon teardown I found a dished piston, no scoring in the cylinder and a good crosshatch pattern. The squish with the dished piston was about .060 measured with solder. I decided to install meteor piston and use moto seal instead of a base gasket. I did not hone the OE 45L cylinder. I did not remove the base block.
The results were solid.
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The ring end gap was about .007.
Squish was about .024 with the Meteor piston and motoseal.
Compression after 4-6 tanks of fuel is about 152 psi.
The OE carburetor remained good. After clipping the ears from the white and red plastic limiters it tuned nicely. It is a very good running saw a solid performer.
Initially the second saw had 100psi compression, and a profoundly clogged air filter. This saw would start but had no power.
Upon teardown I found the same dished piston, no scoring in the cylinder and a good crosshatch pattern. The squish was about .060 with the dished piston. I again installed a dished piston, used motoseal instead of a base gasket. I did not hone the OE 45L cylinder. This time I removed the base block after measurement and had a friend deck the block on his old Bridgeport Mill. I used motoseal between the plastic case and the original seals.
The results were mostly solid.
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The ring end gap was again .007.
Squish was slightly narrow at .015 with the shaved block, Meteor piston and motoseal.
Compression after 3-5 tanks of fuel is about 175psi .
The OE carburetor was not good – clogged somewhere. Turning the High mixture screw counterclockwise failed to keep no load RPM below 13000. I replaced the carburetor with a cheaper aftermarket carb from H & L Supply. This worked dandy. Oh, also, I corked the primer bulb for the new carburetor because it is the older style and didn’t accommodate the primer bulb.
Regarding both saws I learned…..
The muffler screws and cylinder base screws WILL loosen when heat cycling the saw. I recommend Loctite 222 Medium strength, high temp, AND carrying a 4mm T-handle hex drive. Check the bolts after the first 3 heat cycles, then after the first 3 tanks of gas, then after the first 3 days of use/sharpenings. My bolts are stable on 1 of the saws, but a couple bolts still moved slightly on the other saw.
There really isn’t much/any difference in noticeable performance between 152 psi and 175 psi. So, I don’t recommend removing the base block for the extra procedure.
I didn’t port either of these saws or their mufflers. I purchased an aftermarket muffler, and the exit orifice diameter was identical to the factory muffler.
The Proline Solo Tach is a gem. I tried 2 other well reviewed Amazon tachometers, but the readings were bouncy and inconsistent. The Amazon tachometers are in the garbage can. I initially set the no load rpm at 12,500, but both saws are now set at 13,000.
The parts from H & L supply have been good, reliable and accurate.
The clutches…. The clutch drums and bearings from Amazon were terribly sloppy – despite many good reviews. The Oregon clutch drum from H & L fit wonderfully. This probably doesn’t matter in use, but I like stuff to fit well.
The flywheels…. I broke the convex key nubbin off my flywheel because I ran the saw without the nut properly tight 18-22ft / lbs. This was dumb. The flywheel spun and ripped the aluminum nubbin off the flywheel. I learned the nubbin isn’t really necessary and did a visual alignment of the flywheel and crankshaft – adding maybe 5-10 degrees of advance. I torqued the flywheel and it held position – even when pulling the cord against 175psi compression.
I don’t know what the OE idle WAS, but I couldn’t really get the tuning good for a nice low rpm idle. Both saws idle at about 3800-4000 rpm. Maybe this is due to the higher compression.
Both saws are dandy performers. With a sharp chain and fairly low rakers, one of them pulled an 18” bar nicely through a 20” oak log a few days ago. The other saw has a 16” bar and I kinda prefer this.
Parts for the 350 have been darn available and are mostly the same across the 346xp, 353, and 350.
For you:
Regarding your fuel leak: It looks like your fuel line to the carburetor is completely disconnected at the tank via the picture above. Both of my saws have the adjacent white gas tank breathers removed. I suppose they are prone to get clogged. Both of my saws leak on their side after filling completely, but are otherwise fine.
Regarding cleaning: A dirty saw will cut just fine too, but, after a rough cleaning , placing the larger case parts in the dishwasher when your wife is away from home works great ! Be sure to clean the dishwasher filters afterward. And maybe run the dishwasher cycle again to remove any potentially bad smells.
I apologize for any typing errors and hope some of this is helpful.
Sincerely,
Dave
Your 175PSI saw should out perform your 150PSI saw, especially with a timing advance. Are you sure you went the right way with your advance?
Regarding parts, 340, 345, & 350 are basically the same saw with the 350 having a riser block to accommodate a cylinder setup like the higher class (metal body) 353/346XP. 350 also has the adjustable oiler (& corresponding drive gear) of the 353/346XP.
It's common for bolts to loosen off on these, especially on the muffler. Loctite works well as you have found, fitting a modified 353/346XP muffler support also works well
