I have a husqvarna 359 that is 8 years old and it won't run at idle. I have had the carb adjusted 3 times in the last year and still having the problem. I got a compression gauge and I'm only getting 90 psi out of it. I've taken the muffler off and the piston and ring don't look too bad. My question is am I over looking something and if I should just get a new ring, or spring for a new cylinder kit. Thanks for any help.
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Can you see the cylinder at all? Is it scored? Could you have a crankcase seal issue? That could be causing your problems.
I'm not sure here is a couple pictures of the piston thru the exhaust port. I thought if the crankcase was leaking that it would rev uncontrollably.
![[Hearth.com] 359](https://www.hearth.com/talk/data/attachments/141/141615-73ceae135c9708fcb00324e339f9c056.jpg?hash=WVgXCVdvHx "[Hearth.com] 359")
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Jon1270
Minister of Fire
That piston doesn't look great, but it doesn't look terrible either. The random bright dots are odd.
Is the decomp valve working properly?
Is the decomp valve working properly?
I think so it had a lot of carbon build up. The pictures didn't show it but there are horizontal lines from top to bottom on the piston. I think that is what the bright spots are.
What type of compression gauge do you have? Do you have one with a valve in it? If you do and you're only getting 90 psi I think it may be time to pull the top end and inspect it.
Just FYI any saw with lower than 120 psi I'd consider taking a look at the top end. What type of oil have you been using? Keep us posted on what you find.
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The 359 was popular with modders, so there are a lot of discussions on that topic if you want to go down that path.
There was an issue with the plastic clamp on the intake boot. It would fail and cause an air leak. If I recall correctly, husqvarna updated the part to a metal one.
There was an issue with the plastic clamp on the intake boot. It would fail and cause an air leak. If I recall correctly, husqvarna updated the part to a metal one.
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It has the metal clip. I mostly used the stihl ultra. I had a buddy years ago that had a problem with a 55 using 50:1 and so I've been running it at 40:1. After some reading this weekend that may not be the best idea.
![[Hearth.com] 359](https://www.hearth.com/talk/data/attachments/141/141666-b8d73d2738a4b46a94c912db6cbad582.jpg?hash=o8CVn3p7Fy "[Hearth.com] 359")
![[Hearth.com] 359](https://www.hearth.com/talk/data/attachments/141/141667-6b8e71badaa1ac07e0ef75a8f7680620.jpg?hash=OhCSTEwbQj "[Hearth.com] 359")
![[Hearth.com] 359](/talk/data/attachments/141/141668-6555e6bbd82632ec68aeaa3fc8dfc434.jpg?hash=J9MBTzlPIX)
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When you run a finger/fingernail over the cylinder do you feel any scoring? If not it may just be a case of putting new piston and rings into it to get it back to normal. If there is some scoring, it may be time for a new cylinder/piston.
Do you tune the saw slightly rich or have you ever adjusted it?
Yeah but his compression was also very very low. 90psig is way too low for a chainsaw.
Ultra at 40 or 50:1 should not be a problem if saw is tuned with it. More of a problem would be detonation as a result of using low octane gasoline instead of smooth, consistent ignition from higher octane gasoline.
There are a couple places where I can feel scratches on the the piston and cylinder. I'm going to order a hyway cylinder kit.
i still think you should do a blowdown test. that cylinder and piston look good from where I'm sitting.
What's I've found is that at 40:1 a modern properly tuned saw tends to get a lot more carbon buildup in the exhaust and on top of the piston. I ran Mobil M2T synthetic before I switched to Amsoil Saber when they discontinued the Mobil and last time I pulled the muffler off my 372 it looked really clean with very little carbon buildup. A lot of that can also be how rich you have the saw tuned for as I have most of mine tuned for 2-300 RPM richer than max RPM on my saws.
So, what do you run yours at? I tend to run mine at 40:1 and haven't really noticed any major issues with carbon buildup. I use Stihl cheap stuff, but my gasoline is my own special blend of herbs and spices.
I run at 50:1 on everything even my old 056. For gas I'm using either non-ethanol premium which has become easier to find in the past year or I run 100LL AV Gas barring no non-ethanol gas.
Same fuel here (no 100LL for me, though). the 40:1 is what I use on absolutely every saw, even my old ones, too. We aren't too far off. Someone could just decide to split our decision and make themselves some 45:1 
Same fuel here (no 100LL for me, though). the 40:1 is what I use on absolutely every saw, even my old ones, too. We aren't too far off. Someone could just decide to split our decision and make themselves some 45:1
I really think it has the most to do with how the saw is tuned. The first thing I do with a new saw is remove the adjustment stops and re-tune the saw for 2-300 rpm below max. (Assuming it has an unlimited coil).
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