Hi All:

     Can you tell me an easy to do this.  I did it today for the first time and had a thrill a minute.  There must be an easy and quick way to do this. Share please.

                                                                                                                                             Tia,

                                                                                                                                             Frank McCune

You did it in what  motor, ?  different engines  take different  ways to install them, some you can put the piston/ring in the sleeve before inserting, others  you cannot

Randy

Randy

That motor is  pinned on the  intake side of the motor, and towards the back, between the rear main intake port and the  boost port, make sure the piston is pointing that way where the pin is, they came with an  arrow on top of the piston pointing the way, but you can just scribe another one in   if you cannot  read it
The  rings  are cut on the back side at the  gap  to clear the pin  so the  gap goes  at the  pin.  Some engines like the  ST 51  have the  rings  cut about an 1/8 in  away from the  gap  to clear the  pin, so  double  check  your  motor  BEFORE  you install the parts .,
IF you buy a ring from a  aftermarket ring maker, and he machines the pin clearance in the  WRONG place, and tells you  to twist the  sleeve to match, just look for a  new ring that is  stock

Be aware  some engines  the ring has top be install top to bottom correctly, there is a top and bottom  to some rings
Many of ringed pinned  engines  have  a  bevel  cut on the bottom of the sleeve  to  compress the ring  as you slide  the sleeve over the top of the piston  and into  the  case,  this is  doen  ALWAYS  at  top dead center,  and  you make have to twist and  wiggle  the sleeve  a  very  SMALL amount  to get the  ring to compress.  CAUTION  many people ding or  break the  ring installing them as they are too aggressive with the technique to install them
Check the ring  by just squaring  them up in the  sleeve  and using a  feeler gauge,,, DO NOT use  a  dental pick


Regards
Randy

     Hi Jim & Randy:

     Thanks for the replies.

     I used the dental pick to check to see if the ring gap was in the correct position.  This was done by removing the head and with the piston at TDC and applying a very small radial force to the ring gap to determine if the ring was correctly on the pin.  I doubt that any damage happened to the ring.

     In the past, I used a worm screw type of hose clamp for a piston ring compressor.  Try it and it may work for you.

                                                                                                                              All the best,

                                                                                                                              Frank McCune

ST G.51 was the only one I've done. The cylinder was a heat-shrink fit into the case, which I doubt would be a problem on the OS. It was a lot of sweating bullets and application of the heat gun, but came out just fine. If the piston and ring go into the cylinder, the ring gap has to engage the pin, or it won't go. My two G.51's will soon be fitted with ABC setups...YAY! That's the way ST should have made them to start with.  Steve

I still do not see how a person could get the ring to go in if the ring notch was not on the pin. It would push it out enough so that it would not go in the sleeve. Seems like the ones I have seen the recess for the pin was at the ring gap. I just learned that is not always the case. But the only big Tigre's I have owned that were ringed, was a blue head 60, and the old single ring 46 that I have now. As I recall niether one of those were pinned.

Randy's correct, of course! It is a Tom Lay rebuilt G.51...which had a Frank Bowman ring, per his standard rebuild. So, I never saw a stock G.51 ring. The ring wasn't seating, no compression, some shiny spots on the cylinder wall, so I took it apart and gave it a decent crosshatch with a brake cylinder hone. The cylinder (new from Tower) didn't look like it had ever been honed...ever. The cylinder of this particular G.51 is a shrink fit, which I thought was odd. This feature made assembly a PITA, but I got 'er done, the ring seated, compression appeared, and it will now fire off with a digital starter.  Steve

When I was flying R/C pattern, I flew with a friend that ran YS 120 four strokes. He found that if the ring gap was in a certain place they ran better. He would go fly them until they ran best, shut the engine down and hope the ring did not move. Then he pinned the ring there. Then they always ran consistently after that. Depending on what side the gap was on was where they had the best running compression. You could tell it in the air before he pinned them at times they would just lose power for no known reason. He figured it out. Pinning the ring solved the problem. No port windows to worry about.

When I was flying R/C pattern, I flew with a friend that ran YS 120 four strokes. He found that if the ring gap was in a certain place they ran better. He would go fly them until they ran best, shut the engine down and hope the ring did not move. Then he pinned the ring there. Then they always ran consistently after that. Depending on what side the gap was on was where they had the best running compression. You could tell it in the air before he pinned them at times they would just lose power for no known reason. He figured it out. Pinning the ring solved the problem. No port windows to worry about.

  Same with the ST46, the end would migrate freely and it clearly made a difference in how it ran. I was to the point of figuring out how to pin the ring, when we went to the Golden State meet and found Paul Walker flying his 40VF-powered model. Then I stopped having to care about ring end gaps ever again.

     Brett