Topic: inserting pistons into sleeves without damage?

[KingCustomCycles.com]

What techniques are you guys using to insert the pistons into their bores on reassembly?  I broke an oil control ring yesterday and am looking for ideas.  Thanks!

[Gordon]

I use my fingers.  Inner two cylinders first, then outer two. 

This is more difficult if your sleeves are bored out and the bottoms are no longer tapered. 

[scottly]

Hose clamps, the poor man's ring compressors..

[dave500]

fingers and finnesse,a screw driver can be used to just nudge the odd misbehaving ring inwards,i never have any trouble.

[Jon]

+1 for hose clamps.

Don't tighten them just pull them up till they are touching.

Cheers
jon

[cafe400f]

I oil them up good and just use my fingers and finesse.  Take your time, that is key, there is no need to rush this step.

[jneuf]

Can't you get a ring compressor for pistons that size?

[tlbranth]

It's been a while but I stabilize the 2 'up' pistons by putting wood slats front to back across the top of the crankcase for the pistons to sit on. Once that's done it's not too traumatic. Don't remember if I used ring compressers or fingers.

[fire113]

...I used my fingers and a screwdriver.

[MCRider]

I jsut did my 888cc kit. Big bore kits are harder as the taper has been removed from the bottom of the sleeve. Stock sleeves are a piece of cake. Oil and they slide right into the tapers.

I used wood blocks to stabilize 2 pistons at a time. I used hose clamps. I'll post pictures and clamp sizes soon. They are in my build thread but several pages back from the most recent postings. Went pretty easy.

[domer]

Ive yet to rebuild a sohc4, but I've always made ring compressers out of hose clamps and sheet metal...Chevy's, fords, vw's and 1 Harley... always worked, just make sure the edges are extremely smooth and take your time. the sheet metal idea came after i snapped a ring on a vw using just a hose clamp. but that could have been the patience thing too!

[Gordon]

For me it seems like any kind of ring compressor or hose clamps would just get in the way of themselves and be more trouble than they're worth.  I guess if you have sausage fingers, though, that route might be preferable.  I'm not a big guy, so my fingers aren't all that big either. 


And don't go making any kind of assumptions based on that...

[MCRider]

Ive yet to rebuild a sohc4, but I've always made ring compressers out of hose clamps and sheet metal...Chevy's, fords, vw's and 1 Harley... always worked, just make sure the edges are extremely smooth and take your time. the sheet metal idea came after i snapped a ring on a vw using just a hose clamp. but that could have been the patience thing too!

On the CB750, all 3 rings will fit entirely in the width of the clamp, so no need for addtl metal.

[MCRider]

For me it seems like any kind of ring compressor or hose clamps would just get in the way of themselves and be more trouble than they're worth.  I guess if you have sausage fingers, though, that route might be preferable.  I'm not a big guy, so my fingers aren't all that big either. 


And don't go making any kind of assumptions based on that...

I think that is true on a stock cylinder that has the taper. Have you tried it on an 836 or bigger? At 888cc, my taper was nearly gone. On a 900-915+ I'm guessing there is no taper and the hose clamps are at least more necessary, if not absolute.

[MCRider]

First you'll want to pick a hose clamp where the buckle is not wider than the strap.

We blocked up 2 pistons

and inserted 2 first, removed the clamps, clamped the remaining pistons and finished


Important to pick a clamp nearest to your diameter so there's not a lot hanging out and the clamp is as round as possible. Tighten them down snug, then back off a tad so the clamp floats on the rings, and can slide down as the cylinder slides down, feeding the rings into the sleeve.

[Gordon]

For me it seems like any kind of ring compressor or hose clamps would just get in the way of themselves and be more trouble than they're worth.  I guess if you have sausage fingers, though, that route might be preferable.  I'm not a big guy, so my fingers aren't all that big either. 


And don't go making any kind of assumptions based on that...

I think that is true on a stock cylinder that has the taper. Have you tried it on an 836 or bigger? At 888cc, my taper was nearly gone. On a 900-915+ I'm guessing there is no taper and the hose clamps are at least more necessary, if not absolute.

Oh, I know.  I mentioned the lack of a taper on bored cylinders in my first post.  KCC didn't say what the bore size is on the engine he's working on. 

[MCRider]

"Oh, I know.  I mentioned the lack of a taper on bored cylinders in my first post.  KCC didn't say what the bore size is on the engine he's working on."

Sorry, missed that. 

[tlbranth]

Make a taper

[Hannibal Smith]

I did it just recently, and did the "2 up in the middle" trick, and used a nice amount of Marvel Mystery and did it by hand...................but I had 4 hands, so it wasn't too bad.
I will admit the hose clamp if done properly is superior, but we had no problem just using our fingers and talking between the two of us.
I personally don't sweat staggering the rings (except the oil assembly of course) so we rotated the gaps to where we could access them with our meaty claws.
I would definitely use a nice amount of oil too, Marvel is going to burn in just fine (on break-in IMO) and really makes it nice. I know this because I put rings in basically dry about a week before, and the difference was big.

[octagon]

great pictures mcrider - to add 2 cents, i've found it helpful to use light oil between the clamps and the piston-ring assembly (this is on several car and truck motors over the years, but the idea is the same.) then tighten down and back off, as you say.
i've used the butt end of hammer to tap the pistons in, just letting the weight of the hammer fall on the top of the piston from a height of a couple of inches, very light, so it anything is hanging up you can tell before any damage occurs.

[MCRider]

great pictures mcrider - to add 2 cents, i've found it helpful to use light oil between the clamps and the piston-ring assembly (this is on several car and truck motors over the years, but the idea is the same.) then tighten down and back off, as you say.
i've used the butt end of hammer to tap the pistons in, just letting the weight of the hammer fall on the top of the piston from a height of a couple of inches, very light, so it anything is hanging up you can tell before any damage occurs.

Absolutely! I left those details out and they really make it easier. Oil them up, I suirt a bead into the cylinder and let it run down the crown of the piston into the ring area below the clamp. Also, tap it (the top of the cylinder) with a rubber mallet, taking care to keep the cylinder level side to side and front to back. Light as you say, checking and feeling for a ring that may have slipped out of the clamp. IF the cylinder doesn't drop a little with each tap, something is holding it up.

[754]

Dont ever use a screwdriver, try a popsicle stik or similar or plastic fork handle end.
 Problem with hoseclamps, they are not perfectly round, they have holes that may allow something to hang up..the shim of softer material wrapped inside the hose clamp is rounder, softer, and less damaging.
 Regarding the bevel or chamfer, any is better than none. I realize the sleeve is thin there on big bores, but it is not load-bearing in use.. just be careful when moving cylinder while off the bike..cand chip or deform easily.
 Hastings makes some beauty compressers that are like shimstock, with a clamp that curls it tight, and a quick-relest, they have worked well for me on other sizes..