CL350 piston rings and bore question

[Jramos13]

hi guys, today i got my piston back from the machine shop, since this is the first time im working with an engine at this level of a complete rebuild i just wanted to ask if everything was done right the pistons fit fine in the bore, a bit snug/tight and there is almost no gap for the ring, i got the 65.5 pistons from bore tech, the instructions says a minimum ring end gap of .010. The machinist told me to let him know if the bore needed more honing, that it wouldn't be an issue, but im not sure if i should maybe dremmel the rings a bit to make the .010 gap or hone the jugs a bit more, here some pics and a video:

when test fitting it, it create a slight drag mark:

click for video

 

[AlphaDogChoppers]

What the fuck kind of machinist are you using? Sounds like he doesn't know shit about engines.

You do not fit rings by honing the cylinder. The cylinder is honed to fit the pistons. Each cylinder should be custom fit to the piston that is going into it. The service manual gives the specifics for where the piston is to be measured and what the clearance between cylinder and piston should be. Where the piston is measured is critical, because pistons are tapered and not necessarily round. (They change shape at operating temperature. For instance, the top of the piston gets hotter, so it is smaller to compensate for the additional thermal expansion.

Once the bores are sized to fit the pistons, THEN you check the ring end gap.The ring end gap compensates for thermal expansion of the ring, so if it's too tight, the ring will bind in the bore, and that would be bad. Service manual says the ring end gap should be 0.0059" to 0.0138". If you are on the tight end of the range, break in carefully. Second compression ring should be a couple thou wider to avoid ring flutter.

Using a Dremel to adjust your ring gap sounds like a bad idea. You should read up on how to do that.

 

[Jramos13]

Sadly im From PR not a lot of MC machinist down here, anyway, i was checking with a feller gauge, and with a .04mm wich is the closest to .0015 its fits excellent all around except in the front and back skirt that it wont go in at all so do i need to tell him to bore it a bit more to fit the feeler gauge?

 

[Sonreir]

Bring him the pistons. You don't bore a cylinder without the pistons in hand. Big red flag if he didn't ask for the pistons the first time around.

 

[surffly]

Bring him the pistons. You don't bore a cylinder without the pistons in hand. Big red flag if he didn't ask for the pistons the first time around.

This

 

[Jramos13]

i did gave him the pistons with the jugs, but im just not sure if the bore is too tight, like i said i can get the feeler gauge fine around except in the front and back part of the piston skirt where it just wont go in

 

[crazypj]

It is possible to bore with stock pistons and not have them to measure.
Cylinder looks pretty rough to me and I don't see a cross hatch?
You need to measure pistons 90 degrees to pin, about 10mm up from bottom of skirt then hone bore to be 0.0015" bigger
That should give you correct ring end gap.
Don't use a Dremel to set ring gaps, use a file if they really need adjusting (even if you have to buy a diamond needle file off e-bay)
You should be looking at something like this when it's finished

 

[Jramos13]

^ what i thought, i just measure them and the gauge wont even go in between the skirt and the wall! so i guess i will be taking them back to the machine shop guy, the crosshatch is there really good, just the angle of the picture

 

[rockcitycafe]

^ what i thought, i just measure them and the gauge wont even go in between the skirt and the wall! so i guess i will be taking them back to the machine shop guy, the crosshatch is there really good, just the angle of the picture

no no, you should be taking them back to another machine shop guy, if this dude can't fit pistons right the first time, there's a slim to none chance he's going to get it right the second time, and last I saw Slim was leavin town

 

[rockcitycafe]

It is possible to bore with stock pistons and not have them to measure.
Cylinder looks pretty rough to me and I don't see a cross hatch?
You need to measure pistons 90 degrees to pin, about 10mm up from bottom of skirt then hone bore to be 0.0015" bigger
That should give you correct ring end gap.
Don't use a Dremel to set ring gaps, use a file if they really need adjusting (even if you have to buy a diamond needle file off e-bay)
You should be looking at something like this when it's finished

p.s. PJ I really want to see your boring setup, I've been reading a lot about boring cast iron and have some ideas on improving it, but seeing a setup that's proven is way better for me

 

[crazypj]

Sorry, don't have access to boring bars or Bridgeport any longer, few pics in the HondaCB360 album on photbucket.
Haven't tried boring in my cheap Chinese mill yet
Cylinders need to be set up on tall parallels with spigot down, either use studs through normal holes or clamped on solid edge.
Don't take more than 0.010" at a time, even when your going 1~2mm oversize. (that's the main reason it costs so much to have major over bores done, takes a long time and multiple passes)
Up to 0.040" is fine when boring aluminium for bigger liners

 

[surffly]

You are trying to fit the feeler gauge where and its not fitting?

 

[rockcitycafe]

Sorry, don't have access to boring bars or Bridgeport any longer, few pics in the HondaCB360 album on photbucket.
Haven't tried boring in my cheap Chinese mill yet
Cylinders need to be set up on tall parallels with spigot down, either use studs through normal holes or clamped on solid edge.
Don't take more than 0.010" at a time, even when your going 1~2mm oversize. (that's the main reason it costs so much to have major over bores done, takes a long time and multiple passes)
Up to 0.040" is fine when boring aluminium for bigger liners

.010" diameter of DOC? I'll be working on a better clamping setup, I think simply holding the middle two liners in the table vise and boring the outside one isn't rigid enough (the liners are being removed anyway, so I'm feeling free to destroy them). I'll try taking off some carbide for the clearance, also, ever use a wiper on your carbide? I read a lot that it improves surface finish quite a bit at the same feed