Putting piston in reverse?

[popopboat]

Hi, ive made a few questions long time ago about new piston for my 650, ended up with 064 meteor, but as i didnt really need 650, i postponed piston replacement, until now.

As i said 650 piston is pretty much non-existent over here. So im stuck with this one.

Piston ring pins on 064 piston are slightly less "backwards", more on sides.
If i put it the right way, ring gap comes way too close to upper transfers.


If i put it reversely, arrow to the intake, gap comes this close to exhaust.


What are your opinions on this?
How close is too close ?

 

[Shibby]

Exhaust side sees more heat and expansion, intake side sees more vacuum. Sealing on the intake/vacuum stroke isn't as important as sealing on the power/exhaust stroke. At least that's what I've been told to believe.

 

[huskihl]

I’d run it backwards if it was me, as long as you’re absolutely certain that that’s where the ring ends are. Any further away than that, and I would run them the proper way

 

[Nutball]

Make sure the piston isn't narrower on one side than the other. You don't want the Exhaust port to not seal on the sides. Some pistons are wider on one side.

 

[Benwa]

Pictures online are so hard to "measure." For me, if the ring end gap is more than .100" away from the edge of the upper transfer port, I say run it. If it's closer than that, I'd run it backwards. I've run plenty of pistons backwards in saws without issue, but there's gotta be a viable reason to do so. Just one man's opinion of course.

 

[Billy Currie]

Backwards looks like your safest option. It's not pretty, but I think it work.