klickitatsacket
Addicted to ArboristSite
No signs of snagging. Teh piece also looks as though it was broke from the top down and not peeled up.
Boom!
- Thread starter klickitatsacket
- Start date
Help Support Arborist Forum:
No signs of snagging. Teh piece also looks as though it was broke from the top down and not peeled up.
Goat
ArboristSite Operative
From the pics it appears to be a white casting that slipped through QC. Only real way to tell is to see the whole fracture surface....
Lakeside53
Stihl Wrenching
I've seen this on the older 066 - use of paper gasket and loosening cylinder screws. The cylinder just breaks due to fatigue. I posted a pic a while back when we were talking about cut away cylinders, poly flywheels etc.
I bet the cylinder broke loose and the piston damage was subsequent
I bet the cylinder broke loose and the piston damage was subsequent
Last edited:
klickitatsacket
Addicted to ArboristSite
Interesting thoughts guys. This saw did not have a traditional gasket. It was ringed and dirko was used to seal it. This is standard practice here. The screws were tight as a drum. One thing I did forget to mention thoughis that this cylinder was decked .035 and so was the crown of the cylinder. Compression was a little high.
RiverRat2
Serio Tree Freak
Hand Green Aid!!!!!!!!!!!!
I bet that was a screamer!!!!!!!!!!!!
I bet that was a screamer!!!!!!!!!!!!
Lakeside53
Stihl Wrenching
I assume it wasn't a new cylinder... It could have been stressed and fatigued long before it was modded... High compression etc will add to the stresses Maybe it just couldn't handle it..
If you can exceed the limitations of engineering on a component to the point of severe failure of the component then you have my respect.
That is if it was due to to much power, torque, compression or some other force on a component. Not due to being screwed up...... you know what I mean.
That is if it was due to to much power, torque, compression or some other force on a component. Not due to being screwed up...... you know what I mean.
PES+
Addicted to ArboristSite
Can you post larger pic links of the piston?
klickitatsacket
Addicted to ArboristSite
I pulled the fly wheel today. The timing slipped. Now I do not know if it was before or after the train wreck, but suspect that this could be the issue.
Pest I resized the pictures when I put them on photobucket. My camera is having problems transferring photos again so I am unable to get you bigger pictures right now.
Pest I resized the pictures when I put them on photobucket. My camera is having problems transferring photos again so I am unable to get you bigger pictures right now.
jgrega
ArboristSite Lurker
That is interesting Dean, have you seen that happen before?
motosierra
ArboristSite Guru
Who is going to pay for this saw?.... and how many times has this happen?
Isnt the flywheel keyed?
Also does the piston show any signs of detonation? If it doesnt show signs of deto I doubt the timing caused the failure.
klickitatsacket
Addicted to ArboristSite
this is the first time I have ever seen it like I mentioned in the begining. Also I am paying for it and for the shipping both ways. We completely stand behind our work.
klickitatsacket
Addicted to ArboristSite
keys do not hold the flywheel. The keys are only for lining the timing up. The shafts are tapered and the flywheel is compression fit. If you do not have the flywheel locked down enough you will shear keys in a heart beat. Been there before. Concidering the flywheel was advanced I believe it to have moved after it hit on the upstroke. The piece that broke off of the piston was peeled down and on the intake side.
So you where not using a key or did the key sheer??
At any rate unless the piston dome shows signs of detonation, I dont think the timing advancing was the cause of this failure.
motosierra
ArboristSite Guru
That is commendable.
Nothing sours a business faster than a a FUBAR or perceived FUBAR that isn't taken care of properly.
klickitatsacket
Addicted to ArboristSite
Sorry no key. I pull the keys when I advance the ignition timing. I don't see any signs of detonation or pre-ignition either. I really am beginning to think that this is just a freak occurance. I've talked with a few other builders and they are all scratching their heads on this one.
