Another piston ring question

[CrookedRoadSaws]

Hello, after lurking here for a few months gaining knowledge, (although apparently not enough :bang: ) I decided to upgrade my Makita 6401 to a 7900. Got the new P/C kit and installed it with no problems. However after just reading another post about which way the piston goes, I realized I put it in with the ring opening towards the exhaust. Yea, I know, I should have asked this before, but I put it in the way it was sitting when it came out of the box, so didn't really think much of it.

I have run about 5-6 Tanks of gas through it now, and it runs great. What kind of problems could this cause? Is it too late to turn it around? :help:

Thanks, Mark

 

[begleytree]

IMO, if it was going to cause a problem (like catching and breaking) it would have by now.
as it turns out, I and lakeside have been discussing my FIL's old 028wb that has the piston in backwards. this saw has never been opened up, FIL bought it new 25 years or more ago and used it to heat his house for 15 years.
then other saws catch as soon as you turn them over sems like
-Ralph

 

[Lakeside53]

You have one chance in two of getting it around the right way, but why not pull the muffler and check...

Don't run it if it's wrong..

 

[manual]

Welcome to the site.

Hmmm. What if you opened the box and it was up side down. :monkey:


If it were my saw I would turn the piston around. 5-6 tanks may have seated the ring. just run it and the ring will re-seat again. do a compression check after 5-6 more tanks of gas. just to ease your mind.

Stick around here I appreciate your honesty. My guess is your not the only one that has done this.

 

[Dan Forsh]

IMO, if it was going to cause a problem (like catching and breaking) it would have by now.
as it turns out, I and lakeside have been discussing my FIL's old 028wb that has the piston in backwards. this saw has never been opened up, FIL bought it new 25 years or more ago and used it to heat his house for 15 years.
then other saws catch as soon as you turn them over sems like
-Ralph

I dunno, if he's been reading the thread I started where it turned out the piston was in backwards, that one had been in for a while. I asked my BIL if he'd had any work done on the saw in the time he'd had it and he said 'no'.

I'd guess you can get away with it for any length of time or not as the case may be, instant, months/years or never seems to be possible.

If you know it's wrong, you've got to change it I'd say. It takes 2 minutes to pull the muffler for confirmation and it's not such a big job to correct.

Dan

 

[PES+]

Sometimes saws are mis-assembled from the factory. I have seen it from all manufacturers. Depending on the exhaust port shape it can either cause a failure quickly or just wear the ring and or port edge faster than normal.

 

[CrookedRoadSaws]

Thanks for the replies everyone! I will break the saw back down and turn the piston. Heck, I even had the Dolmar parts list/diagrams and didn't bother to look at it. I seem to be really good at making bad decisions even though I know better :bang: What I meant by out of the box, was that the piston was in the cylinder with the ring gap facing the exhaust, so i just "assumed" that that's the way it should go. I gotta quit doing that!
Sure hope this turns out ok, I really like the 7900. Have a 20 and 28" bar for it. The 20" with 8 tooth rim is awesome!