grape hone question
 

Flex hone website shows grape hones available in 180 and 320 S/C.

I am guessing we want 320 for our Alusils. Correct?

Anyone?

I would think for alusil 180 would be to coarse, but I am not sure, some guys have just used a scotch brite pad to rough up the cylinders. Maybe my posting will get you some more educated answers.

My thoughts, too. Seems like 320 should work. Can anyone shed some light?

Don't know about Alusil, but I've seen people say that Nikasil can be honed, while others have said that it can't. Seems to be alot of uncertainty in this area. I know this doesn't help, but I'm as curious as you are. I have a set of used 2.7 RS pistons w/ Nikasil cylinders, and I don't know whether to hone them, or not. There appears to still have some cross-hatching, but would like to be able to hone them, all the same.

The 180 grit is what I have used, with good results. I understand this is pretty fine as far as honing a cylinder goes.

I used the 180 flex hone on my 3.2 with Nikasil cylinders. I'm not sure where you are getting your information from 911s. The controversy has always been over the Alusil cylinders.

OK, 2 votes for the 180 grit. No one using 320??

There's a bunch of background on this in the "re-ring alusils?" thread. Snowman's a big proponent of the grape hone, and we're getting ready to settle the controversy with some genuine science.

So, I got two that say yes to honing Nikasil cylinders, both agreeing that using 180 grit is acceptable. Anyone else? Just want to be sure before attempting to hone mine.

I talked with Jon at EBS racing about honing my Nikasil. He said they do not hone them but rather blast them with a special very fine compound to just lightly rough them up. I got them back from him and noticed no difference in finish to the human eye, so my guess is that whatever you do it should only be done lightly...
After 50 miles or so I had no smoke in my exhaust so I assume the rings seated well. I've got 1100 miles now and everything seems to be running well.

Pat

I replace the rings in my dirtbikes every 10 hours, pistons every 20. The all have Nikasil cylinders. We scotch-brite 'em usually or occasionally run a 320 up and down a couple of times if hone's laying around. just to scrape the dead piston off. Reassemble dry, but these are 2 strokes....

Just run the 180 grit grape hones, with a generous ammount of honing oil or transmission fluid, for about one minute at about one stroke per second at about 300 RPM. It will give you an ideal finish for new rings and they should seat within a few minutes of startup.

I suspect that the scotch brite is nearly the same but more uncontrolled.

When honing, you want a crosshatch with a 30 degree angle towards the plane of the rings. A ball hone can do a fabulous job creating this pattern if used skillfully. I'd take that pattern over anything I'd create with steel wool any day.

No input on the grit, just wanted to put in for the ball hone.

George

You're not really cutting a crosshatch with a grape hone. Nikasil's hard.

This thread went from Alusils to Nikasils... back to Alusils.

Snowman, I seem to recall that a grape hone on Alusils should be just a quick few strokes for 15 seconds or less, not a minute.

Extensive testing on Nikasil lining has shown the it can be honed using a Sunen CK12 honing machine using a diamond hone. The dingle ball hone will not cut Nikasil.

One thing to remember that the honing process is not only to establish a good cross hatch, but will actually help straighten a cylinder bore.

Grape hones are only used as a final step in conventional honing or to refresh good cylinders. They do not change the shape of the bore, at all, however silicone carbide, the cutting material on a grape hone, will cut any cylinder, ie put a cross hatch pattern in it. THe cutting ammounts to just tiny scratches, removal of microscopic peaks in the cylinder wall, leftover ring material, and smeered metal from a conventional hone. Sunnin has equivalent honing tools. Look under the subject of Plateau Honing.

That was someone else who said 15 seconds. I said one minute. In any case its not critical with this type of hone. You could probably go 10 minutes if you wanted and not change the result. 15 seconds may be ok but would be on the short end of it.