Ok it was the wind,,,, honest....

Well, thats my story and I'm sticking to it.

But heres the deal, I need your help with a FA65 Saito. It had about 1/2 gallon of fuel through it before, I bent the pushrod tubes. When I loosen the head to get the tubes out to straight them and inspect the pushrods I took the head all the way off. I didnt pay any attention to the position of the ring and I am sure it has move since I straighten the pushrod tubes. I cannot tell by the cylinder where the gap in the ring was running. So heres my questions. Does the ring stay in one place in the cylinder when running? I assume so. What will the difference be if I can get the ring back in the spot it was broke in at?

Thanks for the help.

On a 4-stroke like your Saito it doesn't matter. The ring isn't pinned and it's free to turn whichever way it wants to. There are even some 2-strokes that allow the ring to turn freely on the piston (the K&B .40 is one) but they have fenced ports to keep the ring from falling into them. Most all of the modern schneurle ported 2-strokes have pinned rings to prevent them from turning and hanging up on a port.

But wont it lose compression if not in the original wear patterns?

It doesn't matter what position you put the ring in. Just put it back together and go. The ring rotates while the engine is running.

I'll do as recomended. I always thought the wearing "groves" kept the ring in place. But I am always learning.

Mighty Mouse

How do you like your FA 65 I bought one this winter and am really anxious to fly with it.

Used to live in Mankato,MN and MPLS.

The FA65 is a cherry. Stong case and good power. Like most Saitos, it idles well and is very reliable. I perfer the 56. It is power to weight ratio is better. What will you be putting it in? My was in a AT6. Now it is looking for a new home. Leaning toward a corsair like the Lanier.

Mighty Mouse

Put it on a heavy 40 size float plane she's all broke in and just waiting for the Ice to go out. what area you in now?

Totally in the opposite end of the country. Picayune, Mississippi. About 50 miles from the coast.
The 65 should fly the float plane well if it isnt too heavy. I have a cub in the wings almost completed that I want to put floats on. It will have a OS 70 on the nose. I 've never flew off water but think it would be great.

Mighty mouse

Oh it's the cats meow float flying My club field is about 1/2 hr away and a good lake is only a block away so if I get a chance in the late evening out to the lake I go. no it's not to heavy I had a GP 42 on it last year but it was pretty doggy so this 65 should bring it up on plane fast . take care.

On my ringed engines I always take a piece of 400 wet or dry sandpaper, wet it with WD-40 and sand a light cross hatch pattern back into the cylinder.

Just a real light sanding to mostly break any glaze present.

The ring then re-seats itself to any position you install it in.

Been doing this for over 30 years on RC engines and even up to the cylinders on my 1996 Triumph 1200cc Daytona.

I have a Fox .50 and a .74 converted to Diesel. Occasionally I dismantle them to see how they are standing up to the Diesel pounding. I always place the ring ends at the widest solid metal in the port area. They never move from there. If you stop and think about it they have no reason to move.
PS Gunship, is that Ted from Cycle World in the Picture?

Interestingly, I have seen them move on K&B 40s and H.B. 40s. Maybe it's because they are Dykes rings?

What in the world does someone's sexual preference have to do with piston rings??

Well...uhhh...mmmm...maybe we should start a new thread?

Briggs & Stratton did a test on an engine with a visible cylinder wall and all 3 rings were rotating while it was running. More food for thought!!