Worn out Decompression Valve

[Raj]

My 066 on the mill has no decomp. I just do what Dave does. Not so bad with the weight of the mill on it.

 

[SeanKroll]

You can replace the decomp valve with a solid plug if you don’t use it. Totally personal preference. New piston and cylinder is super easy but make sure you have a ring compressor or it can be a pita.

Thanks. My shoulder says it wants the valve.

Will definitely get to the root of the problem before repairing.

How does one test seals/ leaks.


My guess is still the carb.

The cylinder is badly gouged in one spot from the ring.

 

[Merle Nelson]

Seals and leaks on gaskets are tested with vacume/pressure guage as I understand it. For clear vids of some of the basics check th Saw Kings youtube channel.

 

[Marc-Antoine]

You make two gaskets from a tire tube, one plain, one with the valve in the middle. Put the plain between the muffler and the cylinder to close the gas exit, same with the valve on the inlet, but screw it with a hollowed plate instead of the carb. Close the impulse tube (if it's separated from the carb boot) with a small pin.
It's ready.
Apply some air in the valve with a pump, hand held or compressor, but set at 7 psi /0.5 bar max. A gauge is interesting for a small leak, but not mandatory for a big one (just hear the hissing) and look at the bubbles with soapy water. If you can get a hand held vacuum/pressure pump, that gives you the both sides of the test.

Don't do that with the carb, as it's much more delicate, or with a very low pressure. Often, the membranes in the carb aren't damaged, only hardened/distorted.
I saw some carb screws becoming a tad loose and giving a leak.

I had a bad decomp valve on a used 066. Not leaking though, but it stayed open.

 

[SkwerI]

For those of you who don't use the decomp valve- I use mine every time on every saw. It isn't because I'm not manly enough to start the saw without it, but it is because I don't want to stress the plastic starter pieces and tiny little starter string any more than I have to. I bet you guys replace your starter rope about every year or two, huh? I might break one starter rope every 2-3 years, out of over a dozen saws. The one I broke last week was over 10 years old.

 

[Burnham]

 

[Buddy]

If it’s still running (forgive me I can’t remember if it is or not) you can shoot it with a little starting fluid anywhere that it might have a leak. Listen for it leaning out and you have found your trouble spot. If you burn your saw down doing this tell people you learned it from Jim.

 

[stig]

Last time I can remember replacing starter parts was this winter.
That was because my young dog had chewed the handle to a little nubbin.

I may be manly, but not enough to start a 661 by holding onto a nubbin.

Apart from that, they never seem to go bad, even though I never use the dec. valve.

But then I mostly don't run vintage saws like many here seem to do.

 

[Cut4fun]

I learned last few years to use my decomps on the bigger saws. My shoulders cant take it anymore.

I laughed when a logger was buying my 385xp and he went to start it without decomp. I was like I told ya it had good psi.

Back 10-12 years ago my 066 had no decomp, no base gasket and 180psi. I had to put a 460 rescue handle on it. Grip it and rip it was no problem. But today it would be for me.

 

[BlackSmith]

First pull on my 090 taught me all I needed to learn about the compression release valve, a lesson I’ll remember.

 

[Burnham]

Yeah...I used to not bother with them, but that was back when I was young and strong, without all the wear and tear in my shoulders that I have today. That's not the case any longer...neither the young and strong part nor the not bother with decomp valves part .

 

[pete mctree]

I have just replaced my tired old 440 with a nice new 461 - I am really enjoying having a decomp for a change in the tree. Never known a leaking one burn a saw up & would be investigating other potential problems thoroughly before rebuilding.

 

[Burnham]

Last time I can remember replacing starter parts was this winter.
That was because my young dog had chewed the handle to a little nubbin.

I may be manly, but not enough to start a 661 by holding onto a nubbin.

Apart from that, they never seem to go bad, even though I never use the dec. valve.

But then I mostly don't run vintage saws like many here seem to do.

Hey! I resemble that remark .

 

[BlackSmith]

Tell that youngster it takes vintage men to run them vintage saws Mr. B... lol

 

[MasterBlaster]

I have never NOT used a decomp valve!

 

[Burnham]

Youngster...

 

[stig]

Well, you do have 3 years on me, Buddy

 

[BlackSmith]

I have never NOT used a decomp valve!

I didn’t know better but I learned better... heh

 

[Marc-Antoine]

I use the decomp valve on the 440 , 066 and 3120xp, but only for a hot start.
When the saw is cold, it seems to take forever to prime the carb, even with the starter "on", if the decomp is activated.
So, no decomp and a manly pull until the first "Burp !", then decomp for the actual start.

 

[SeanKroll]

My MS261 has one. I use it. Electric start would be sweet.

I think that "roll starting" is easier on the shoulders. Its where you rest the bar on the log (nose obviously clear of kickback hazards), and you push with the pistol grip, while pulling the starter cord.

 

[Magnus]

When running saws I try to use it as often as possible.
Its there and help you and saw, why not use it?

 

[Cut4fun]

Was working on a 211 yesterday. Damn I love the easy start feature. Just barely pull the rope out and starts.

 

[Raj]

I'd like to install one on my 066. Need another cover, or I'll just cut a hole.

Any concern with the plug on the cylinder? Loctite on? Soft threads?

 

[Mick!]

Sounds like a recipe for disaster to me Peter.

I use it on the 088 and the 395, otherwise not usually, unless they don’t start 3rd pull then I’ll try it.

 

[Burnham]

I'd like to install one on my 066. Need another cover, or I'll just cut a hole.

Any concern with the plug on the cylinder? Loctite on? Soft threads?

You'd have to be able to keep all metal shards from the drilling and tapping out of the cylinder...