To Hone or Not to Hone

[aquasonic]

Currently, I’m working on a 1958 Johnson AD-12 7.5 HP, that is a survivor of a serious overheat. Pistons and rings are being replaced with new due to overheat scoring. The bore is smooth with the exception of a small scuff area on the exhaust side.

It seems that the generally accepted procedure is to hone the cylinders when replacing rings and/or pistons. Honing is supposed to help with break in by holding more oil for ring/bore contact. There is, however, a line of thinking that honing the cylinders accelerates the wearing out of the bore, and can actually lower compression in the long run.

Here is an excerpt from the website ringspacers.com:

Honing
The other thing people overdo is hone. They want to see a
pretty 350 chevy cross hatch pattern but that is not necessary in
our old engines. You are grinding away precious cylinder wall
material. The extra piston to cylinder wall clearance will allow the
piston to cock around in the cylinder and will break the seal of the
rings. If you can’t resist the extra honing get a piece of emory
paper and do it by hand. When your arm is tired you know that
you are done. Leave the power honing to the professionals who
have modern marvels like oversized pistons in their bag of tricks.

Every case is different, but in this case, I’m leaning toward just a “50 cent” honing using a piece of sandpaper, and skip the Flex Hone.

[Bob Wight]

I would do a light hone with the Flex Hone. I don’t believe the Flex Hone removes material to the point the cylinder is damaged. I’ve always felt it good to knock off the cylinder glaze so the rings seat better. Just my opinion.

Edit – I typically use a 320 grit Flex Hone and only a few strokes that does a nice job of removing the cylinder glaze and leaves a light cross hatch as opposed to grinding away with a 240 grit for minutes on end.

Bob

1937 Champion D2C Deluxe Lite Twin
1954 Johnson CD-11
1955 Johnson QD-16
1957 Evinrude Fastwin 18
1958 Johnson QD-19
1958 Johnson FD-12
1959 Johnson QD-20

“Every 20 minute job is only a broken bolt away from a 3-day project.”
"Every time you remove a broken or seized bolt an angel gets his wings."

• This reply was modified 4 years, 3 months ago by Bob Wight.

[Tubs]

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A "Boathouse Repair" is one that done without having tools or the skills to do it properly.

• This reply was modified 4 years, 3 months ago by Tubs.
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• This reply was modified 3 years, 11 months ago by Tubs.
• This reply was modified 3 years, 11 months ago by Tubs.
• This reply was modified 3 years, 11 months ago by Tubs.
• This reply was modified 3 years, 11 months ago by Tubs.

[rudderless]

Usually I run the hone lightly to check the witness marks. One can tell a lot about the bore with a quick spot with the hone.

If ya don’t want to remove a lot of material use a copper fitting brush powered by a slow drill. Gives a real nice finish. I used a 2″ fitting brush on my 9.9/15hp.

[Mumbles]

There’s two kinds of honing. The first kind is used to remove metal to get a final fit on a freshly bored cylinder. A three stone hone is used for this and you don’t want any part of it. The second kind is to break the glaze or to give a bit of tooth on the cylinder wall to hold oil while the new rings are seating. A Flex Hone or ball hone works best for this as it won’t remove excessive metal and leaves a perfect cross hatch pattern on the cylinder wall. Lightly rounding off the sharp upper and lower edges of the ports with a Dremel and a small ball stone before honing to avoid ring damage will give a finish your momma would be proud of!

[fleetwin]

Well, I agree with most all of the points presented for sure. Honing is actually “boring” to some degree, a bit of metal is being removed. I agree that many people “overdo” the honing procedure in order to get a nice looking cross hatch and not see any cylinder surface untouched by the hone. Using the rigid hones on these two stroke engines usually leads to this condition. Don’t get me wrong, rigid hones (if they are good quality and have the correct grit stone in new condition) do a great job, but you really have to avoid the natural tendency to clean up every bit of the metal cylinder surface…Doing this will probably lead to honing/boring a bit oversize. This is why I usually use the flex/ball hones to “clean up” a used two stroke cylinder, these hones will hit all the cylinder surfaces while cleaning up any burrs on the ports. Two strokes tend to have more wear in the port area for obvious reasons, especially the loop scavenged models.
So, I guess the best place to start is an accurate measurement of cylinder oversize and taper in a few different areas. Needless to say, a nice looking hone job (with flex/ball hone) on a cylinder that is oversize and tapered isn’t worth much, just “looks good”. The tough decision is deciding how much wear is acceptable in terms of how it will affect the engine’s running quality/compression, etc. Needless to say, if the oversize and taper is out of spec, the cylinder needs to be bored oversize. But, like we always say, these engines never get many hours on them, so aren’t really worn out very often. Folks are often fooled by seeing the “original hone” marks still in the cylinder, then assuming there isn’t much wear. But, they have failed to take overheating into account…The overheat condition may have warped the cylinder and caused it to be out of round.
In this case, we are talking about an old 7.5hp that probably does not have many hours on it, but it was overheated. I’m betting measurements will show the cylinders to be within spec for oversize and taper. We will never make this powerhead absolutely “new” again, unless you replace the crankcase with a NOS piece. Brent has purchased NOS standard pistons and rings, and I’m sure the rebuilt unit will have great compression and run like new…These old engines are pretty tolerant to alot of things, and we are not rebuilding the space shuttle or high performace car engine for sure.
I’m surprised reading about someone using my 50 cent emery hone job on a chevy 350 though. Don’t get me wrong, I use this procedure on most OMCs that I pull the head off for an inspection without tearing the powerhead down. The powerhead is apart and will benefit from a light honing job after it has been measured. Give me a call, I have a flex/ball hone for the 7.5hps….D

Correction/addition… The cylinder bores should be lightly honed with a decent hone on any powerhead that is pulled apart/pistons/crank out of crankcase. In Brent’s case, his 7.5hp is all apart, I agree that it should be honed properly/lightly with a decent hone tool. The 50 cent hone job is not appropriate here….

• This reply was modified 4 years, 3 months ago by fleetwin.

[Mumbles]

How do you get the grit out of the ports after doing a 50 cent hone?

[fleetwin]

Just spray heavily with brake cleaner through the ports and down between the pistons and walls with the powerhead facing downwards, blow it out with compressed air, then wipe the cylinders with WD40/outboard oil….It’s only fine emery/crocus cloth, isn’t much dust…. Surely not the cleanest/best practice, but it does break the glaze a bit, hopefully bringing a little better ring sealing back to an old engine.
Again, an engine that is disassembled should be hone properly….

[Bob Wight]

Another question on this topic might be the type of honing oil used. I know lots of folks use 2-stroke oil but I’ve also had good results using a light oil like engine fogging oil. I’d be curious to hear what others have used.

Bob

1937 Champion D2C Deluxe Lite Twin
1954 Johnson CD-11
1955 Johnson QD-16
1957 Evinrude Fastwin 18
1958 Johnson QD-19
1958 Johnson FD-12
1959 Johnson QD-20

“Every 20 minute job is only a broken bolt away from a 3-day project.”
"Every time you remove a broken or seized bolt an angel gets his wings."

[rudderless]

If i’m working in the warm weather I use cutting oil. If its 32f or less I use a light spray oil.

Plateau honing with a brush as a last step removes the sharp tips of the honing groves where the undesirable smearing happens at startup. Google plateau honing. That finish seems a little course..maybe its just the lighting.

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