Rcpilot

My Feedback: (78)

I've got a used Fox 3.2 engine here and I want to put a new ring in it. The old one is worn and the compression is low. Everything else is in good shape. No problems with the cylinder or the piston.

This is a well used engine that I got cheap. I'm going to replace the rod--simply because the bearing races look a little worn too.

The cylinder needs to be honed before installing the new ring--or it's just wasted money. The ring will never seat if I don't hone the jug and knock the glaze off.

So--can I just use a bottoming hone on my cordless drill and some 3-n-1 oil? Or do I need to have this done by a perfesshinal [:-] machine shop?

I know, I know--someone is gonna tell me to send it to FOX. And I can DO that.

I just want to know if I can do it myself?

The parts are cheap, and I'm no slouch when it comes to working on car engines and drivetrains. I've been building and rebuilding cars since I was 10 or 12 yrs old. I've been around a feeler gauge and some plasti-gauge, and I know what a torque wrench is. I've seen the inside of an automatic trans. and even fixed a couple of Turbo 350s.

What do ya think?

Diablo-RCU

My Feedback: (1)

It's a plated cylinder - probably Nikasil. I believe these are diamond honed because of the extreme hardness of the plating. The trouble is, you don't know the thickness of the plating. You may hone through it. The replating services for cylinders are very expensive...about $200.

flyingohio

My Feedback: (2)

You can use a small ball-hone on the cylinder, available from mcmaster. There are also diamond-type brush hones but they are pretty expensive. If you flush the cylinder good n' plenty while you are honing, no worries. That nikasil is very hard. All you really need to do is just knock off the glazing and give the new rings something to grab at a little bit. I hone all nikasil-type cylinders on engines I rebuild... even tho it isn't something that 100% has to be done. Just don't go crazy and you'll be fine.

Rcpilot

My Feedback: (78)

I don't want to use a ball hone because it won't reach all the way down into the cylinder before the balls are hitting the combustion chamber. Then I'd still have a glaze on the top of the cylinder where the rings would be when the piston is at TDC.

I was going to use an end hone or a straight stone hone to get all the way into the cylinder--thereby knocking the glaze off the entire cylinder wall.

A buddy is an old motocross racer. He's rebuilt a lot of 2-strokes and thinks I should only run the hone for a few seconds at a low speed. He recommended 3 or 4 passes at under 100RPM--with plenty of oil. Just enough to knock the glaze off and "dull" the shininess of the cylinder again.

Sound about right?

Antique

My Feedback: (4)

This has been debated before...Honing is for cast iron cylinders..IMO

cu. in.

Why not call Fox and get their opinion? I have toured their plant and saw a number of Sunnen and Superior hones there. These are the rigid style of hone, not the flexible type that has been mentioned here. Fox is usually pretty fair on repair costs, if you decide to have them do the work.

By the way, do you know Mike Pratt? He used to live in your town but went to work for Sig Mfg. (again) a couple of years ago. At this point, I have lost track of him.

Bruce

mglavin

My Feedback: (31)

I’d suggest you approach this with caution as Diablo noted the Nikasil plating is likely pretty thin. Ball stones are way to coarse IMO. Typical over the counter stones are not fine enough either I suspect. You might consider checking with a local automotive machine shop. I have honed small cylinders on Sunnen rod hone with great success.

Other than that your motorcycle buddy is on the right track IMO.

Antique

My Feedback: (4)

Google "Nikasil" for the info...Only mention of honing in 3 or 4 pages is using diamond hones after replating to make it SMOOTH.The silicon carbide in it is too rough as applied....Nikasil is .0025-.003 thick...

Rcpilot

My Feedback: (78)

What about using Krokus (sp?) cloth? And doing this job by hand?

I've been told thatthis would knock the glaze off. I don't know what it is. I've never seen it. I was told that many machine shops use this cloth.

Is it similar to Scotch Brite cloth?--only rougher or more course?

RCIGN1--you said that honing was for cast iron cylinders. I don't doubt your knowledge. So, what can I do with this Nakasil lined cylinder? Just slap the new ring in it and go? Or does it need some kind of prep before re-ringing it?

Thanks guys.

RTK

My Feedback: (1)

I believe that is his meaning, although I will not speak for Ralph. BUT thats what I would do based on my limited knowledge. Slap and go.

Antique

My Feedback: (4)

Crocus cloth is very very fine abrasive on a cloth backing, used for very fine polishing..
There is no need to break any glaze on the cylinder wall..Breaking the glaze is for iron cylinders...Glaze on an iron cylinder will make it very difficult for the rings to seat ..Breaking it accelerates the process...If a chrome or Nikasil cylinder wall is roughed up, it WILL make the rings seat a little faster..It will also continue to be rough and wear out the rings faster...
Put it together and go...
Maybe you could call Brison and get their take on this, might be interesting...

Rcpilot

My Feedback: (78)

Ralph:
I'll take your advice and just put the new ring in and fly it.

Thanks for your help.