bore de glazing
 

what do you use to deglaze a 2 stroke cyclinder bore? i was planning on using 600 grit sandpaper.
because i have heard that a hone could destroy a cyclinder bore. this would be on a gas engine.

Light going over with 600 will be OK.

Don't sand the bore if it's plated!!

Why do you want to? Normally not required as it is on automobile engines.

If it is not required, then why does a new cylinder have a cross hatch from a hone in them ??? Answer because there finished with a diamond hone for 2 reasons to maintain the proper size and to give the cylinder a cross hatch for proper ring seating.
Even with a spring hone on a chrome plated cylinder your not going to remove any material worth taking about with just a few strokes.
In Fact a man can work up quit a sweat just trying to remove a couple of .0001's of and inch.
Who ever told you that an hone would ruin a cylinder is someone I wouldn't put to much stock in as far as engine's go.

Frank Bowman makes the pretty much undisputed best rings you can buy, and he recommends a light sanding with 400 or 600 sandpaper. I'm not going to argue with the guy that makes the best rings myself....

AV8TOR

Well if this is one of those engines that uses the Chrome plating, nickle plating, Nikasil or Alusil, I would not touch it with anything. You would only use the 600 grit paper with a light touch on a steel cylinder sleeve. But if the steel sleeve was hardened then I would not touch it with sandpaper either. I don't think anyone is using the ceramic coatings on a gas engine cylinder (except for NV-Engines), but you wouldn't touch it with sandpaper either.

That Nikasil or Alusil method tends to look like a plain aluminum bore on the cylinder but it isn't.

My feeling is that if it is a chrome or Nikasil bore, the only thing that is going to happen with a quick sanding using 400 or 600 sandpaper wet with some solvent is a removal of the oil glaze anyway. You are not going to damage the chrome unless you get really carried away. Then you might damage the chrome right at any sharp port corners/edges. That removal of any oil glaze is exactly what we want for the new ring to break in properly.

AV8TOR

I tend to agree with the above. A bit of sandpaper isn't going to do much if anything to the surface except remove the glaze. You won't be removing any measurable thickness from the plating material. Even a diamond hone would take a bit to get through the plating.

I do not sand the bore at all with sandpaper. Some particles off the sandpaper can get embedded in the bore. Use acetone & a scotch brite pad. This is what is also used to clean varnish off a piston so accurate measurements can be done accurate for checking piston dia for wear. I worked in a engine test lab building prototype engines for a large company.

If you can embed a grain of sandpaper in a hard chrome cylinder you are one strong guy,or have some pretty soft chrome considering the fact that most good sandpapers won't even scratch a hard chrome cylinder.
They don't use Specialized grinding and Honing equipment just for the sake of using it, it is the fact that hard chrome is HARD and requires it to be machined and worked correctly.
I will bet anyone in here that there arm will tire out long before you can do any measurable damage to a hard chrome plated cylinder.
Even Nickle is a challenge to do and does require the same sort of equipment to machine as the chrome does.

i failed to state, the engine is a quadra / pioneer early eighties , i dont know if its plated. the bore on this
is very clean no scratches no pitting , looks very good , mabey i should just leave it alone, the piston also looks good.
just needs rings, good info here , i apreciate it.

The rings will still seat if you don't do anything to the bore.

Take a piece of sheet aluminum, and "mike" it with a micrometer. Let's say it is .032". Then start sanding it as vigorously as you can with 400 sandpaper. Then "mike" it again. You won't even take off 1/2 a thousandth of an inch. (.0005") Chrome, nickel or Nikasil is many times harder than the aluminum.

AV8TOR

I agree with you on a good quality chrome bore, that is true. Many cheap engines out of china do not have a quality chrome bore. Notice a lot of photos have been placed here showing "shinny bore syndrome & a lot of other crappy looking cyl bores. Damaged pretty easy.

Capt'n, that shiny bore syndrome was common early on with the Chinese engines but I bet you don't see that much if at all any more ... at least on the better Chinese engines. Their quality has come a long way in a very short time. Regardless, as av8tor said, a bit of very fine grit sandpaper is not going to cut through any plating, even cheap plating. We're not talking a 18 grit grinder disk here!

Well let me put my foot in my mouth as I have been around engines sense I was out of diapers, So if the bore is just shiny with NO vertical carbon or varnish marks the preceding ring never really seated the same goes for the piston, normal use over time with proper fuel and oil will produce these marks, so if it was me I would use some 600 wet/dry and some J/D no drink that first then the alcohol and reassemble with the new ring. I have found with my many gassers weed whip, chain saws and my model engines a good ash less 2cycle oil and std gas (no ethanol) @ 32/40 to1 for the first hour of run time will seat the ring, then change to your choice.


Cheers Bob T

PS with the plating thingy if you look at it with a mag/glass say 20 pwr on in a new cylinder you will see slight inprofections. this is what ring seating takes out.

Its not so much the size of grit....its the type of sandpaper...stay away from silicone carbide paper....

+1

cheers

i found a set of rings , and the engine is back together, but i didnt sand anything, the bore
is definatly plated with something, because a magnet wont stick to it. gonna fire it up soon.