railer

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Nov 4, 2005
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98 RM125, third hand, used to belong to pro racer, probably had un-countable top-ends done on it. I myself have never done top-end. Gonna be due for one pretty soon. From reading around this forum on the topic, I've decided I'm going to hone the cylinder, but don't know what kind of ball hone to get. Also, if I hone it, how do I know what size piston and rings to order so that they will properly fit?

Sorry if this question has been asked a lot, but I'm trying to get as much info on it as possible before I attempt it.

Brian.
 

Rich Rohrich

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Jul 27, 1999
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Eric Gorr's Forward Motion 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.
 
Jun 4, 2006
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" 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 "

This is exactly what happened to my bike.
the last owner honed it with the spring-loaded finger hone.

Now goto bore the damn sleeve again
 
Last edited:

railer

Member
Nov 4, 2005
125
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Thanks Rich.

Maybe I won't hone it then. Guess I gotta have a look-see at the cyl. first.

Maybe just some scotch-brite will do the trick, ey?

Brian.
 

Rich Rohrich

Moderator / BioHazard
LIFETIME SPONSOR
Jul 27, 1999
22,838
16,902
Chicago
magneto said:
Why would you want to use a hone that is 10% smaller than the bore?

It's really only necessary on the electrofusion coated Kawasakis. These cylinders had really poor plating that can get torn up if you get too aggressive with a bore sized hone. You can use a bore sized hone for all the other plated japanese cylinders.
 

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