Problem with o66

[hardy steve]

Just started in garage yesterday after sharpening chain. One hour later went to start and use. Pull rope and feels like not much compression .Some restiance pulling cord but not like normally.And won't start at all. Any thoughts thanks

 

[BobL]

First thing is to get a compression meter on it and see what it really is.

Is the decompression valve stuck open?

 

[mtngun]

Pull the muffler and look inside for damage.

 

[tlbsg]

Pull the muffler and look inside for damage.

simple test for good compression hold saw by pull handle and let it hang saw shouldnt drop fast if comps good

 

[hardy steve]

Ok compression checked it. With a cheap tester you hold to plug hole.75 pounds it had. It's getting spark too, but not a real bright spark . Looks like it could be hotter.

 

[flashhole]

75 lbs is waaayyyyy low for that saw. It should be over 150 lbs. Pull the muffler and inspect the piston for scoring. Were the room lights on when you were looking at the spark?

 

[TPA]

If it was running one minute and then not the next, and compression tests that badly, I suspect you may have straight gassed it. A saw will not start at 75 psi compression.

 

[discounthunter]

pull the muffler look at the piston.oh and pull the muffler and look at the piston.if it hasnt been mentioned pull the muffler and look at the piston.if it was me i would pull the muffler and look at the piston.

 

[TPA]

Yes, pull the muffler.

It is very simple...6 screws and your in! Torx T25 I think.

Have your flashlight handy.

 

[hardy steve]

Ok finally got a chance to pull muffler.Looks like very minimal wear.The piston skirt looks good all the way down.The cylinder has very little wear and it is within 3/16 of top.Somthing I did notice as I was pulling rope.Seemed like alot of gas bubbling on each stroke. maybe carb shot craps and washed rings out.This was a new piston and cylinder 2 years ago. Maybe 6-7 cords cut with it.Most everything I get is what nobody else wants.

 

[TPA]

Somthing I did notice as I was pulling rope.Seemed like alot of gas bubbling on each stroke.

I could use some clarification here.

 

[tlbsg]

I could use some clarification here.

are u still working on chainsaw

 

[discounthunter]

im betting it was an aftermarket p/c. might be cheap rings. post a pic thru the cylinder if you can. some peoples idea of wear differs.

 

[hardy steve]

I will try and post tonight pics.

 

[showrguy]

please explain your compression tester, and how you actually used it..

from what you said you held a cheap tester up to the hole ??
if you have what i think you have, and did what i think you did, that compression reading aint even close..
you need a screw in tester with a schreader valve, and pull the saw over several times till compression stops building..that'll be your actual reading..

make sure you have the short male adaptor for the tester, most automotive testers use/have a much longer screw in fitting (will cause piston damage)......my cheap test kit has both..

my .02 cents
good luck

 

[hardy steve]

You are 100% right on tester.Thats what happens when you loan tools out ,and don't remember who's got it. Yes I puts saw in vice and used a hand held tester.I figure it's off some,but I know from using saw the compression isn't there that was. I've never had a compression release on it.Personal torture and no one else can use. I will try and post some pics

 

[hardy steve]

Ok pics didn't work. I'm done messing with it. I'm taking apart this weekend and really checking out. Keep you posted. I will say this with plug out pulling rope as I would try to start gas was spraying out of cylinder.Just seems way above normal.

 

[Mad Professor]

Is the hole for the decomp in the cyl plugged off?

The decomp on my 066 sticks and gives problems starting. I only use it for cold starts now.

 

[hardy steve]

OK update on saw! The compression release was cracked leaking by it.Have now idea how happened.Went down to stihl dealer picked one up.Good as new.I did do a comp test with good tester for piece of mind. About 105Thanks for everybody in put .

 

[cutforfun]

Compression is at 105? You are still about 40-50psi low, and about 75psi lower then I like mine