What causes low compression

[Ed Penney]

I have ran across some sloppy machine work with cheap rebuild kits. Get in the habit of measuring everything, piston to bore, pin height, ring gap, crank throw etc...yes everything. I had one that wasn't even honed. Italian kits are worth the extra money. They take more pride in their finished product. ALWAYS

 

[bwalker]

Lack of lubrication on the piston during installation

No. You can out them together dry with no I'll effects. While I don't reccomend it, I've known plenty of people that have.

 

[bwalker]

The strato`s are taking longer to break in, there are more than one line of thought on this subject. The use of synthetic oils is causing some of it as it takes much longer using synthetic oil over the older petroleum based oils. Some think the extra gulp of air is causing the piston to run cooler, thus the ring takes longer to heat and rub in . Another possibility is that there are different alloys used in the rings or the cylinder coatings, all hypothetical at this point however. The same goes for the tolerances these new saws are machined to, the engineers are always trying new materials and machining techniques.
A two ring piston creates more friction and thus heat so I would expect them to break in sooner than a single ring. The verdict is still out as far as I am concerned on what lasts longer, a single ring or two ring piston and ring combo.

Where to begin? Just about all of what you posted is not true.

 

[bwalker]

I kinda always thought that two rings was a tradeoff. They would not run as high RPM, and more friction, but would help to keep the piston centered.

Two rings seal better and because heat is dissipated through the rings they run cooler. They also longer in many cases.