Commissioning new engine

[Carlb]

I found it quite easy to just compress each ring in succession by hand, no tools needed.


Carl

[oliver90owner]

With the original design, the piston was removed by removal of cylinder.  Piston will then come out of top or bottom.

Rebuild could be the hard way - piston fitted to crank and carefully lower block (well raise piston with the block supported) and the rings are fairly easily coaxed into the bore .  The other way is drop the piston in the bottom of the cylinder, then carefully replace the block onto the crankcase.  Ueithr way needed minimum tools for fitting the piston back in the bore as the bottom edge was chamfered for easy fitting.

The simple modern way is to buy a ring clamp, fit to piston, and gently tap piston into the bore from the top - just like millions of car engines.  Ring clamps can be the simple 'grip' type, for one size of piston, or the adjustable ones which can be expanded, wrap around the piston and are tightened with a screwdriver, allen key or similar.

I have two - one will do down to about 60mm and the big one up to about 150mm or so.  I think either will do a CS piston.

Regards, RAB

[Ronmar]

Depending on engine wear and carbon buildup, getting the piston out the top can sometimes be difficult.  They usually always go out the bottom fairly easilly.  If you have the head off, you are probably 90% on the way to removing the cylinder.  

Instead of messing with lowering the cylinder down on top of the piston and working the rings up into the cylinder while trying to support it, I put the piston/rod into the inverted cylinder on the workbench.  You must keep the piston from falling out the bottom of the cylinder while you are re-installing it onto the block.  The easiest way I have found uses a large magnet.  I have a few of these, they are a large horseshoe magnet salvaged from a radar magnetron.  I am sure other types of strong magnets could be made to work also, they just need to be strong enough to lift the piston/rod assembly.  I put the magnet on top of the piston and put a wooden stick thru the opening across the top of the piston and cylinder.  This holds the piston at the top, and I set the whole assembly down onto the block.  Once in place, I rotate the crank up to meet the rod big end and put the rod cap in place.  Use an approprate socket extension when tightening the rod nuts so you don't bend the dipper(don't ask me how I know this:().  

[Geno]

(well raise piston with the block supported)
Regards, RAB

I do mine this way. I rotate the flywheel with my knee while using 2 small sticks to compress the rings. I stagger my rings 180° and in line with the wrist pin/gudgeon.

Thanks, Geno

[rcavictim]

I have always reassembled my engines after a re-ring and hone job by staggering the ring gaps according to a 120 degree pattern, not 180 degree.  Have I been doing this wrong?

[Crofter]

I usually alternate 120 deg offsets with all gaps on the minimum thrust face. I have seen it proposed that the gaps tend to walk around some anyway when running unless they are pin located like in common 2 strokes.

[sailawayrb]

I like the 120 deg alternating offset.  Also be sure to check ALL the rings for correct gap tolerance.  I neglected to do that once, had a ring with too little gap, the ring jammed in the piston after engine came to temp, and scratched up the liner pretty bad.

While experimenting with different liner protrusions (to prove to myself that liner protrusion has little to do with the imfamous head gasket coolant leakage), I discovered that it is easy to get piston back into head from the bottom of head.  Here's how you do it...  Put properly sized angle iron (or something else suitable) between bottom of head and top of crankcase so the head is just propped up high enough such that top ring in piston is just below bottom of head with the connecting rod at it's lowest point.  Then compress each ring, one at a time, as you rotate the crankshaft (to move connecting rod upward and hence piston upward) to insert piston into head.  Once all the rings are nicely in the head, remove the angle iron and lower the head onto the crankcase.  I have a small ring compressor that works well, but I think one could use their bare hands if you had to using this method.

Being somewhat ultra conservative when it comes to these engines, I wouldn't start one up until AFTER I had first disassembled everything, removed all the paint from everything, inspected for and removed casting sand from everything, inspected flywheels for internal casting cracks (at least using gasoline and talc if on the cheap), checked and machined parts to proper geometry and tolerance, and repainted both outside and inside of engine before assembling properly.

[vdubnut62]

I have always went with the 120 degree method myself, and have always had really good results.
Ron,

[WGB]

I did the 120 degree, made sense to me.
I made a ring compressor out of .018 stainless steel and big hose clamps.
I didn't check the end gap, trusted the Indians, my bad!

[mike90045]

I did the 120 degree, made sense to me.
I made a ring compressor out of .018 stainless steel and big hose clamps.
I didn't check the end gap, trusted the Indians, my bad!

What's the spec for the end gap ?  Different for the oil ring ?

[BruceM]

I made a ring compressor from a scrap piece of galvanized sheet duct metal. Vice grips or just fingers on the two right angle tabs will do the job. I clean and oil the inside surface before use.  I figured zinc is soft enough to not scratch the rings.  It's worked well.

[Crofter]

Really I think a ring expander to get the rings neatly on and into their grooves in one piece is more of an issue than squeezing them into the cylinder.

Once a person has ever heard that terrible "snap" sound that comes from breaking a piston ring (or a threading tap!) he is very shy about going there again!

[sailawayrb]

I did the 120 degree, made sense to me.
I made a ring compressor out of .018 stainless steel and big hose clamps.
I didn't check the end gap, trusted the Indians, my bad!

What's the spec for the end gap ?  Different for the oil ring ?

Not less than 0.012 inches, same spec for all rings, and a fine metal file...

Per JKSON manual "place the ring in lower part of the cylinder, square with the bore, and measure the gap between the two ends with a feeler gauge.  The correct gap is not less than 0.012 in. (0.310 mm)."

[mike90045]

couple of pop's - but no running. 

  After lifting the engine clear of the shipping pallet, and orienting it on the cow mat, I wanted to go ahead and fire it.  Antsy from just looking at it and the photos. Make it do something!  Got fuel pump purged, and the HP line, and finally, got the "squank" from the injector. Gave a go at it several times, was able to crank past TDC for several revs before I ran out of steam.  Got some white smoke from the muffler, but that was it. Did it a couple times.  My buddy did it too. His first try, he was not to full speed when compression went to full, and it bounced back on him, Wow he said! He got up more speed, and same thing, a couple puffs of white smoke, and he was out of steam. IR thermometer showed head at 51F Air was 54 F chilly.. 

  Next got the diesel truck, hooked up jumper cables, and tried the electric start,  released compression and was able to get a couple of "Pops" out of it, and more, darker smoke, but that's all. Repeatedly. never fired more than once per cranking attempt.  Maybe I still have some air in the lines somewhere, but the injector seems to squawk each time.  Gotta pack up and head home now though, I'll gather ideas for my April 2010 visit. 
Low compression from dry rings?  air bubbles? too cold (had no propane torch to preheat air), wrong phase of moon?

Pics:
http://www.facebook.com/album.php?aid=2030711&id=1196643274&l=76eb578eb0

[vdubnut62]

I beg forgiveness in advance, but is a "squank" even remotely related to a "skank"?
Sorry, it's late and I couldn't resist
Ron
Sound like either the timing is off or the valves are out of adjustment, maybe a piece of crud on a valve seat.