Boom!

[klickitatsacket]

The piston did'nt get snagged in a port did it? Matt

No signs of snagging. Teh piece also looks as though it was broke from the top down and not peeled up.

 

[Goat]

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]

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

 

[klickitatsacket]

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]

Hand Green Aid!!!!!!!!!!!!

I bet that was a screamer!!!!!!!!!!!!

 

[Lakeside53]

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.

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..

 

[jhellwig]

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.

 

[PES+]

Can you post larger pic links of the piston?

 

[klickitatsacket]

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.

 

[jgrega]

That is interesting Dean, have you seen that happen before?

 

[motosierra]

Who is going to pay for this saw?.... and how many times has this happen?

 

[bwalker]

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.

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]

Who is going to pay for this saw?.... and how many times has this happen?

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]

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.

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.

 

[bwalker]

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]

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.

That is commendable.

 

[bwalker]

Nothing sours a business faster than a a FUBAR or perceived FUBAR that isn't taken care of properly.

 

[klickitatsacket]

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.

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.