Ball Hone or not? Update 8-12-06
This is a thread off of Macdizzy's message board it is a good thread, so good I hate to see
it get lost in the archives forever.
The thread started 10-17-2000
I need some info on a ball type cylinder hone. Where do I find one and what size do I look for? I need
something versatile enough to fit 66mm to about 69mm. I have never used one but have heard that
they are better than a stone type.
Try contacting www.hiperf.com they're a sled orientated shop, but two strokes be two strokes. I saw
in their catalog that they had Flex-Hones for sale. I highly prefer the flex-hone over the flat stone
style. They tend to remove material slower, which is good for "us" rookies. The flat stone style can
catch the edge of a transfer and make the job "fun and interesting"....
Check any machinist or industrial catalog or go to your nearest industrial shop and you can order any
Flex Hone that you would like.
Do these hones have to be an exact size for the application or will they work on a range of sizes? I
would like one to work with all my possible bore sizes, from 66mm-69mm.
Try http://www.goodson.com/ they have about everything you need for engine building.
How do you keep the balls out of the ports when using a ball hone? I know if you use the right flat
stone hone the stones and guides are not affected by ports.
You might also want to read this http://www.sunnen.com/auto/tech_8.htm
The balls on the Flex-hone do spread slightly. Typically the hone is 10% larger than the bore size. But
they don't grab and or do any damage to the port window that a flat stone style will do(unless it's a
sunnen type machine with very long stones).
A 3 mm range is acceptable. You should be able to buy a hone that will fall into your needs.
Thanks for the help guys. I called Goodson and got some questions answered. I also am going to
order a ball/flex hone for $30.00 that will fit 66mm to about 68mm.
I'm not that crazy about the way a ball hone affects the edge of large port walls - especially large
exhaust ports. The rough balls fall into the ports far enough to disturb the finish of the port. This is not
very important on stock / non-ported cylinders but becomes so on special ported pieces. The direction
the drill turns the flex hone determines the walls that will become affected.
The ball hone does apply a relatively nicely rounded bevel to the side of all the ports it crosses - that
is, the walls it runs into, not off from. It is of some advantage to run the hone in the clockwise
direction when starting, then reverse its direction to apply the finish to the ports opposite wall. This
allows the ports to have rounded port walls on all their vertical edges.
This type of hone does apply a bit of a bevel to the top and bottom of ports too but in most cases it is
not beveled enough this way to be considered finished.
When changing the rings or piston kit ball hones work OK , but for serious work it is simply not good
enough. What is needed is the surface finish a hard straight stone provides. Sunnen makes some
good tools for this, though for many people the cost of these hones are far too cost prohibitive.
Thanks for the info Rick. I plan on using this only when reringing. I leave the boring/honing to
You should end up with a hone that is sized at 2 5/8--66.7mm but that will be big enough for the
69mm bore because they do run bigger than the size stated i had bought one that was 2 1/2" but it
will only work good up to about 67mm so i had to buy a 2 5/8 one after also there are different grits
that are available i would go with a 220 or the 280 but they are available in 120 and 380 also
Here is a email thread between Macdizzy and myself that took place Apr 30th 2000
I was talking to a few friends and engine builders there seems to be
some kind of confusion ( at least for me) on how to hone a 2 cycle engine bore
some are saying to use a 3 blade solid stone and some are saying to use a ball
hone the guys that say use the solid stone hone tell me the ball hone will
catch in the ports and or bevel the sides of the ports.
Can you shed some light on this?
It has been my experience that the ball hones are OK for re-ringing a
top end but I avoid them even then. I prefer to use a real hone - in
this case a Sunnen hard stone, connecting rod reconditioning machine. It
is fitted with long stones that don't catch ports very easily - unless
they're extremely large. It makes a wonderful cylinder hone. The hard
straight stones have the ability to straighten out a bore a little bit
and they let you see the cylinder wear very well. The ball hones put the
cross hatch scratches on the cylinder wall but the soft stones fingers
follow the contour of the bore in a way that makes determining it's
condition is a little tough. When the balls fall into the ports, they
round its vertical edges a bit, but only the dividers that get hit
because of the direction the tool rotates. The cylinder ends up looking
like it should have the hone run in the opposite direction to make all
the port edges have a uniform bevel. Sometimes the small balls extend
quite a bit into the exhaust port of engines that use a single large
hole (like the Pilot) and scratch up the port wall if its been polished.
Otherwise I suppose it really wouldn't matter. The off the shelf auto
parts store three stone hones usually come with 3" long stones that
wreak havoc with ported cylinder walls. Maybe that's the type of stiff
stone hone your buddies are referring to.
Here is what Eric Gorr has to say about hones
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, its 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.
If you have made it this far you are probably tired of hearing about hones, don't blame you, but I am
glad you took the time to read all of this, as Far as I am concerned using a ball hone is a good way to
to make the walls of the cylinder uneven, not by much but look at it this way if you change just one part
of the cylinders size by only .0001 the cylinder will be off by that much and the piston to cylinder clearance
will be off .0001 until you bore the cylinder, not to mention the possible damage you can do to the ports.
Most people think I am obsessed about me cylinder bores, they are right!
I like my cylinder bore to be as perfect as possible, exspessually with the large bore of the Honda Pilot
I also expect to get 300+ hours out of a rebuild and still be able to use the same bore, at 7000 rpm's
the piston is traveling on a film of oil between the cylinder 14,000 times why skimp on cylinder bore
preparation when the life of your motor depends on it?
I still remember my first time using a flex hone when I was rebuilding a 5hp Briggs & Stratton when
I was about 14 years old, no matter what you did you couldn't get a consistent feel during the hone
process not to mention the wobble feel when using it, when you feel the tension on the hone change
you can bet the pressure on the balls is changing and also the amount of material being removed
under that pressure changes also.
Just my thoughts, hoser..
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