Honing the cylinder

[David M]

I know the cylinder bore has some special electro-lining, but what I don't know is whether or not you should hone the gloss off the lining before putting in the new top end. Sorry if this is a stupid question, but I've only rebuilt older iron or aluminum bore engines, and this is something you needed to do to get the rings to set. -david

 

[BRush]

From Eric Gorr’s Website
Honing the Cylinder Bore

Many people have emailed me with questions regarding honing cylinder bores. If you want to buy a hone to deglaze bores or polish off small scratches, then a ball-hone is the best choice. Ball hones are manufactured by Brush Research in Los Angeles, under the brand name Flex-Hone. These hones are available under different labels and they are most easily available from auto parts stores. Buy a size that is 10% smaller than the actual bore size. These hones are available in several different materials and grits but the profile that bests suits both steel and plated cylinders is aluminum oxide 240 grit. A ball hone cannot remove material from the cylinder bore, especially on the hard nickel plated bores. However a ball hone can polish down the peaks of the original hone scratches and increase the bearing ratio. In other words the piston will be touching a greater percentage of the bore. Sometimes that makes the piston wear quicker but if you have to ball hone the bore to remove scratches, it's a compromise. The one type of hone that you should never use on a two-stroke cylinder is a spring-loaded finger hone. The sharp edges of the stone will snag the port edges and most likely damage the hone and the cylinder.

http://www.ericgorr.com/techarticles/twotopweb.html#10 TIPS

That said, I had a hard time locating a ball hone on short notice last time. I called Eric last year for the first top end since he did my big bore kit to ask about honing, he said if the cylinder looked ok, honing was not mandatory and just to wash it well in soap & water.

 

[David M]

That's great - thanks

 

[Canadian Dave]

If you don't have a ball hone Dave you can also scuff up the cylinder wall with some Scotch Brite.

David

 

[David M]

Thanks Dave,

I was thinking of using steel wool, but I like the idea of the scotchbrite. I think it would be less likely to do any damage.-david

 

[2strok4fun]

I did a top end on a well used RMX the other day, and was wondering about honing. I took EG's advise as NOT to hone unless there are scratches. So I used scotchbrite to remove oil glaze that was present from blowby. I did rub in a cross-hatch pattern for what its worth. This did expose the original cross-hatch. The scotchbrite may have done the same flattening of the hone, but it looked better and gave the "feel good" I did somthing feeling.

 

[canyncarvr]

Just above the already quoted EG paragraph is:

Cylinder and Exhaust Valve Cleaning

Does your cylinder have burnt-on mud on the outside, heavy brown oil glazing on the cylinder bore, or gooey oil on the exhaust valves? If so, here is a tip for cleaning those parts without flammable cleaners. Go to the grocery store and get a can of aerosol oven cleaner. This stuff is great for cleaning the carbon from the exhaust valves without completely disassembling them. CAUTION: Oven cleaner attacks aluminum, so don't leave it on the cylinder for more than 20 minutes. Oven cleaner can be used on both steel and plated bores.

The oven cleaner will help loosen the oil glazing on the cylinder walls. Then, you can use a Scotch-Brite pad to hone the cylinder walls in a crisscross pattern. Wear rubber gloves when you use oven cleaner and flush the cylinder afterwards with soapy water. This will neutralize the acid in the oven cleaner and break the molecular bond of the oil, so the debris can be rinsed away. Sleeved (especially Kawasaki cylinder bores) are vulnerable to corrosion after cleaning. Spray some penetrating oil on the cylinder bore to prevent it from rusting.

Caution: Certain types of cylinders corrode quickly after the cleaning process, so spray the bore area with penetrating oil to displace the water.

So...another point re: scotchbrite. Also, the oven cleaner and water displacement issues are good hints.

Of course, everyone followed Brush's link in the first place and read the whole thing.....so quoting it again is redundant...'eh?

..steel wool would be awful. The cylinder would need to be cleaned, then cleaned, then cleaned again to get rid of (hopefully) all those 'lil corrosive nasty particles left behind. You would probably end up using a scotchbrite pad to remove the particles from the hone pattern anyway! ;)