Did a search without any luck, so...
Can anyone suggest a method for re-installing a ringed piston in an Enya .35? I've done it on K&B .40's without any problems, but they're low-tension Dykes type rings.
I can't seem to compress the Enya ring enough to get it started. Is there a tool available?

Thanks,
Scott

Look for a pin in the ring land

Look for a gap somewhere on the ring tha fits over this pin

Is this a Schneurle ported engine?

If so, it will have a pinned ring:

In the ring groove of the piston will be a small - and hard to see - metal pin. The ring gap must line up with the pin. The pin is there to prevent the ring from rotating and getting snagged on a port in the sleeve.

David

Oops! w8ye beat me to it.

Ah, I see the pin now....THAT would make a difference!

Thanks.

Cross-flow engines, like the K&B .40, typically have several vertical bridges across the intake and exhaust ports. These little openings are too small for the ring to get hooked in, so a pin is not needed.

Schneurle ported engines usually have four large, un-bridged openings in the sleeve that can allow the ring to expand enough to get snagged.

When you re-assemble the engine, make sure that the piston pin/ring gap travels between ports and not over one. You might have to rotate the piston 180° to get it right.

David

You let the ring gap come across a port and there will be no end to the frustration

It will be difficult at best to get the end of the ring out of the port

Oh dear! Been there, and did not always get out all that well!

I'm embarassed to admit that I didn't know about the locating pin and tried to get the piston in with a tiny tap from a tack hammer.
The new piston and ring are now on their way from Enya.
Live and learn! I'm 58 now, so by the time I'm 273 years old I'll have it all figured out!

Scott,


Please see the photos below.

And please note; the notch in the ring can either be at the gap, or somewhere else, like in the Super Tigre ring.

Installing a ringed piston in the cylinder, if you don't correctly 'index' the notch in the ring, with the pin in the ring-groove, is impossible and for most who 'try harder', it usually ends with having to buy yet another ring...


You're lucky!

Me too. Slipped a piston in the cylinder and then proceded to turn the piston around inside the cylinder to line up the connecting rod with the crank. The ring went past the boost port on the side of the engine and the ends of the ring opened up in the port. [:@]

One scratched cylinder, busted ring and dented piston later I had myslef a nice paperweight. [sm=lol.gif]

Lesson learned. Line the piston/rod up BEFORE you slip it into the cylinder because you don't want to turn/twist it to line up the rod with the crank pin AFTER the piston is inside the cylinder.

Quote:

ORIGINAL: Rcpilot

...Line the piston/rod up BEFORE you slip it into the cylinder because you don't want to turn/twist it to line up the rod with the crank pin AFTER the piston is inside the cylinder.

Rcpilot,


In any engine with a one-piece crankcase (that does not have the hole in the back, to allow insertions of the wrist-pin); such as the OS.50SX, the piston is in the crankcase cylinder casing and the con-rod bottom end is already on the crank-pin, before you insert the piston into the sleeve.

And then, to prevent any possibility of the ring getting caught in a port, you must insert the sleeve into the cylinder casing, in the correct orientation, so you will no need to rotate it.


In the Enya .35 (two-part crankcase), you need to install the piston into the sleeve, in the correct orientation; and then you insert the whole assembly into the cylinder casing, also in the correct orientation...

The con-rod should face the crank-pin following this, without it being necessary to do any unnecessary twisting...

It was a ST2500 glow engine. 2-piece crankcase, piston NOT on the crankpin before you put the case back together.

Not every engine has a 1-piece crankcase Dar.

The sleeve was stuck in the case. Put the piston in from the top and then try to turn it. Ring opens into boost port...... one scrapped engine.

Fortunately, if the front bearing housing is detachable, you can remove it along with the crankshaft and then slide out the sleeve - with the piston inside it. Then, you can access the port where the ring is hanging and hopefully press it back in to remove the piston.

If the crankcase is one piece, and the ring is hooked, there's not much you can do, unless it's hooked in the exhaust port.

David

Quote:

ORIGINAL: Rcpilot

Not every engine has a one-piece crankcase Dar.

The sleeve was stuck in the case. Put the piston in from the top and then try to turn it. Ring opens into boost port...... one scrapped engine.

I agree, Rcpilot...

But as Dave pointed out in his post below yours; with a two-piece crankcase, the sleeve+piston+ring+con-rod assembly CAN be removed from the top of the cylinder casing...

Yet, you state the sleeve was stuck in the case... Why was it stuck?


If you use heat to expand the cylinder casing (through differential expansion - its aluminium expands more than the sleeve's steel, when heated), the entire assembly can be removed.
...And using a toothpick, or any other 'drift', from the outside of the port; the ring-end can be pushed into the groove, while rotating the piston; to place the gap in a more proper spot...
Or better yet; so you will not have to rotate the ring; you can push its end into the groove, while moving the piston up, or down, out of the sleeve.


I know this will not help that ST 2500 engine of yours, but if you, or anyone else for that matter, ever encounters such a situation again; it must be known that it is not a lost case.

Uh, huh. I prefer the ring in photo #1. Impossible? Not if you are of the school off "Bigger Hammer".

Bill

Bill

Quote:

ORIGINAL: Ram Jet

Uh, huh. I prefer the ring in photo #1. Impossible? Not if you are of the school of the "Bigger Hammer".

I agree, Bill.


However, I would suggest that anyone who is strongly into the "Bigger Hammer" pact, keep at least 2 miles off the nearest model engine; lest be stricken by the 'broken everything' bug...

This is what most broken crankshafts, 'snaky rods' and sheared-off ring-ends come from...

It was stuck from years of sitting. I was a newbie and didn't know how to get it un-stuck. But, at least I can admit it.

Most of the "Don't Do's" I learned the hard way... by ruining something in the process. For example, never twist a stubborn sleeve to get it out. It can gall the aluminum case. Yep, I did that once.

David

I was never a 'newbie'... I was always experienced... [&:]

Yeah, right!...


I have also made my share of mistakes in the beginning; such as breaking a crankshaft and bending the con-rod from a hydraulic lock.


Thankfully, I lately learn almost exclusively, from the mistakes of others...