Topic: Piston and Piston Ring Question...

[Dave-and-his-550]

Greetings forum members! Right now, I have all the pistons off and cleaned up, but two of the pistons have nicks in them, I guess something got in there and damaged them? Here are a few pics:





Should I just grind them down a bit and reuse? Also should I completely clean out the gunk where the piston rings sit, or can I leave some residue in there and install the new rings?

On another rnote, Simple Green doesn't seem to be working so well, should I let the pistons soak in a heavier solvent? Denatured alcohol, or acetone maybe?



Thanks for any tips 
 

[bryanj]

Dont grind or anything except remove sharp edges and ring grooves need to be clean of all carbon if you are fitting new rings.

I wouldnt worry aboy what you are showing uder the crowns, it will be that bad again within 1,000 anyway

[Dave-and-his-550]

ring grooves need to be clean of all carbon if you are fitting new rings.

Thanks, that was my main concern. I'll keep scraping at it then. 

[gane]

Dave, i'm w/ brian, Take any raised protrusions off top of piston crown, leave pits alone. Tip, by breaking old rings a propper sized scraper is made, once lands and pistons are clean (wouldn't worry about insides) measure land to ring clearance and pist to cyl . wall clearance at front and rear at bottom of piston skirts,  at mid travel.  if these are close to spec, throw a new appropriate sized top ring in the hole and push to mid travel w/piston and measure end gap.if under @ .012", hone lightly & re-ring.    Raised lips on piston crown, where debris has passed causes a "hot spot" and cause pre-detonation, Loose lands lead to "ring flutter" and accelerate wear. cyl to bore wear obviously accelerates wear, drops comp,and keeps rings from proper seal.  a couple of things that cause rings to seal are, ring tension, compressed gasses traveling past piston to inside of lands and forcing rings against cyl, and a surface coating on the outer edges of New rings which are abrasive and require a little help (honed cyl ) to seal. sorry for the Tutorioial, hope it helps tho, G

[Dave-and-his-550]

Thanks Gane for the tips. I was reading through the shop manual, and they also mention to check the clearances and gaps as well. I'll be sure to do that. I already had the block honed just a bit. Standard rings SHOULD still work, I'll double check the measurements.

Do these rings look like different sizes to anybody? I swear the darker one is slightly bigger, but they both fit about the same in the top piston ring seats of the piston (Referred to as lands, right?) Not sure which one goes where if they're different.

[bryanj]

Chrome one in top groove black one in second groove all markings face upwards

[Dave-and-his-550]

Chrome one in top groove black one in second groove all markings face upwards

<3

thank u, my noobishness still shows when it comes to the little things.

[Dave-and-his-550]

Another silly question I'm sure, but what is the 'piston boss axis' I'm installing all the rings, and it says on page 29 step 4, "Install so that none of the gaps are on the piston boss axis or 90 degrees away from it. Is figure 77 the correct line up for the rings then?

[bryanj]

Piston boss is the metal arround the hole the gudgeon pin goes in (OK wrist pin to you!)

[MCRider]

Dave, i'm w/ brian, Take any raised protrusions off top of piston crown, leave pits alone. Tip, by breaking old rings a propper sized scraper is made, once lands and pistons are clean (wouldn't worry about insides) measure land to ring clearance and pist to cyl . wall clearance at front and rear at bottom of piston skirts,  at mid travel.  if these are close to spec, throw a new appropriate sized top ring in the hole and push to mid travel w/piston and measure end gap.if under @ .012", hone lightly & re-ring.    Raised lips on piston crown, where debris has passed causes a "hot spot" and cause pre-detonation, Loose lands lead to "ring flutter" and accelerate wear. cyl to bore wear obviously accelerates wear, drops comp,and keeps rings from proper seal.  a couple of things that cause rings to seal are, ring tension, compressed gasses traveling past piston to inside of lands and forcing rings against cyl, and a surface coating on the outer edges of New rings which are abrasive and require a little help (honed cyl ) to seal. sorry for the Tutorioial, hope it helps tho, G

I'll be doing this soon as well. Question: If the piston to cyl clearance is where you want it, but the new rings are too tight, wouldn't it be better to file the ring gap than to hone the cylinder?

[bryanj]

Never yet found a Honda ring set that needed anything doing to it

[gane]

Nor I, However. Have intsalled many Wisco/other rings where manufacturer rec'd checking end gaps.and better safe than sorry. ps chrome ring is top, black 2nd, if stamped, stamp is up. on 3piece oil rings, squease outer rings laterally, they will flex up or down nine out of ten times, it doesen't matter which way you install, but make them agree, and locate their end gaps 180 from break in spacer ring. rings migrate as a matter of course, but give them the advantage of being 130 degerees off set on install. break-in is much contested with manufacrure's recommending lubing pistons and cyls upon install and a brake -in period. as an "old school" racer. I realized such"Break-in" would never occur, My preference is 1 drop of oil per ring land, hone cyl. and wash w dish wash detergent & hot water. wait til a lite haze of oxide appears. assemble and start. It may seem brutal. but it works. on race bikes, break in is measured in laps, not miles.piston lubrication is primarily by splash, you must be the judge. g.

[Dave-and-his-550]

I'm kind of confused about this.

Gudgeon pin, is the piston pin, correct?

The shop manual says stagger the rings 120 degrees apart. And so that none of the rings are on the piston boss axis OR 90 degrees from it. (The hole the piston pin goes in) so why in the below figure, do they show the top ring RIGHT on that piston boss axis...Simple mistake?



So, if this is incorrect, I can just put the top ring say, 10 degrees from the piston boss axis, and stagger the rest 120 degrees from that.

[MCRider]

The last thng.

[Dave-and-his-550]

Anybody have those nice piston ring compressors that Honda made for this application they might wanna borrow to me? 

The "universal" ring compressors seem to tall to fit.

I know someone mentioned another technique to compress the rings, but I can't seem to find what thread it was in.

[MCRider]

Anybody have those nice piston ring compressors that Honda made for this application they might wanna borrow to me? 

The "universal" ring compressors seem to tall to fit.

I know someone mentioned another technique to compress the rings, but I can't seem to find what thread it was in.

Garden variety worm screw hose clamps. Work great except for right at the buckle. You'll need a little patience at that point, and a small flat screwdriver. Also, don't put the buckle on a ring gap.

If your cylinders have any of the taper left in the bottom, its a piece of cake. If you are bored out to where that taper is gone, hose clamps still work fine, you just have to go slow. Some appropriately shaped and placed props under the pisto skirts helps but is not necessary.

[Dave-and-his-550]

If your cylinders have any of the taper left in the bottom, its a piece of cake. If you are bored out to where that taper is gone, hose clamps still work fine, you just have to go slow. Some appropriately shaped and placed props under the pisto skirts helps but is not necessary.

Luckily the cylinders do still have the tapered bottom. I figured this would make it much much easier. We'll see what happens when I get there. Gotta paint the block first. Thanks for all your help MC. I'll report back how things went.

[MCRider]

If your cylinders have any of the taper left in the bottom, its a piece of cake. If you are bored out to where that taper is gone, hose clamps still work fine, you just have to go slow. Some appropriately shaped and placed props under the pisto skirts helps but is not necessary.

Luckily the cylinders do still have the tapered bottom. I figured this would make it much much easier. We'll see what happens when I get there. Gotta paint the block first. Thanks for all your help MC. I'll report back how things went.

Squirt oil in from the cylinder side, on the cylinder walls, let it drip down into the taper and onto the pistons. The rings will slide into the taper as the hose clamp falls away. Do 2 pistons at a time, 1-4 and/or 2-3. Some can do all 4 at once, but thats a lot to kee[ track of. The hose clamp should be just tight enough to compress the rings, but not so tight that its fast to the piston. You should be able to turn the clamp with the rings around the piston, just barely.