High Quality Chainsaw Bars Husqvarna Toys Hockfire Saws

HELP! I'm stumped...

Sloughfoot

Pinnacle OPE Member
Yearly GoldMember
Local time
5:58 PM
User ID
26879
Joined
Jun 7, 2023
Messages
582
Reaction score
1,403
Location
Norcal
Country flag
It's not an AM cylinder, it's a KS. First time I've ever had this problem to this extent. I'm hoping it's the ring or cylinder. The only thing is the gouge above the exhaust port roof. Maybe that's making it so low on compression that it won't fire. I don't subscribe to the theory that 100 psi is enough to fire off a chainsaw. But that's just me
Yeh, still a problem if it did fire.
 

Stump Shot

Disciple of Monkey's
GoldMember
Local time
7:58 PM
User ID
1377
Joined
Jun 5, 2016
Messages
32,967
Reaction score
208,771
Location
Northwoods of Wisconsin
Country flag
Here you go..
The top 5/8" or so of the cylinder is the critical part of making compression. If there's any disruption there, it could be what's giving you trouble.
Hard to see just what's going on in the pic, but something looks suspect at the least. Whether it's glare or reflection from the camera, I can't tell. If you run your finger along and feel anything that's not smooth as glass, that's a problem.
 

dangerousatom

Super OPE Member
Local time
8:58 PM
User ID
11828
Joined
Feb 25, 2020
Messages
215
Reaction score
551
Location
Quakertown, PA, United States
Country flag
That image is a bit hard to read but I must agree^ the first 10degrees from TDC look like there's a lip-cut-line thing goin on, or the nickel plating is missing up top....? ( not that I can believe you wouldn't see a defect like that )

Random question: Is the pin in the piston for the ring alignment?

:crazylick: Its going to be something stupid im sure
 

cuinrearview

Handy dood
Local time
8:58 PM
User ID
9248
Joined
Apr 16, 2019
Messages
11,055
Reaction score
76,750
Location
Dowling, MI
Country flag
Everything I build might eventually be for sale, so I don't mess with stuff that looks like that. At 110 psi other factors start mattering more. Is the A/F ratio optimal? Sure, it has spark, but is it a good hot one? I'd bin that cylinder even if you end up finding another problem and can get it to run. It's always going to be a turd without some machine work, and maybe even that can't bring it back. Just my .02
 

cus_deluxe

terms of service violator
Local time
8:58 PM
User ID
393
Joined
Jan 3, 2016
Messages
5,546
Reaction score
26,411
Location
Michigan
Country flag
that little guy? i wouldnt worry about that little guy. seriously that will not cause a noticeable change in compression, certainly not enough to make it not run. looks to me like we are just seeing a reflection on the cylinder wall that people are thinking is rough stuff toward the top yes?
 

cus_deluxe

terms of service violator
Local time
8:58 PM
User ID
393
Joined
Jan 3, 2016
Messages
5,546
Reaction score
26,411
Location
Michigan
Country flag
and if you cant eyeball the difference between .25 mm and .5 mm then you should check ring end gap just to eliminate that as a possibility.
 

cuinrearview

Handy dood
Local time
8:58 PM
User ID
9248
Joined
Apr 16, 2019
Messages
11,055
Reaction score
76,750
Location
Dowling, MI
Country flag
that little guy? i wouldnt worry about that little guy. seriously that will not cause a noticeable change in compression, certainly not enough to make it not run. looks to me like we are just seeing a reflection on the cylinder wall that people are thinking is rough stuff toward the top yes?
Not unheard...QfuGtlO.jpeg
 
Top