hwr
Scoot Member
Posts: 73 
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Post by hwr on Nov 22, 2017 10:31:29 GMT -5
Howdy,
Recently had a fire and my cylinder was burnt but not badly and the bore is a bit rusty.
Already case matched my cases pre-fire so wanting to use this jug.
Its a 69cc 46.6mm diameter polini sport cast iron ac jug.
-What do you think about flex hones?
-What diameter did you use?
-What grit did you use?
-What material did you use?
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Post by jackrides on Nov 22, 2017 13:00:46 GMT -5
Flex hones (small abrasive balls on wire stalks) are the best thing to happen to cylinder walls since boring machines. Size should be the smallest that will touch all sides of the cylinder and they do need their proprietary lubricant which can easily be washed out. The company used to show the difference between their hone results and regular elongated stone hones with a graph that shows the microscopic surface roughness (contour) of the two cylinder walls. Regular hones leave peaks and valleys. Flex hones leave plateaus and valleys. (The valleys retain oil for the rings.) Plateau advantages are increased bearing area for the rings, and far less initial ring wear and resulting metal debris during break-in. Thoughts on grit size?
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Post by 190mech on Nov 22, 2017 15:09:00 GMT -5
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Post by 90GTVert on Nov 26, 2017 15:12:11 GMT -5
I believe the flex hone I'm using is 48mm for the 46-48mm stuff. IIRC mine are 400 grit silicon carbide. 240-400 grit are mostly what's recommended. I think they're easy to use. I tried small 2-3 stone hones before, but I don't think they have any business being inside of a two-stroke. They try to catch ports and it's not cool. www.enginehones.com/technical.html |
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Post by jackrides on Nov 26, 2017 17:00:41 GMT -5
Finger stonehones absolutely catch on the bottom cylinder flanges. Flex hones also put a nice chamfer on ports. The hone tech chart is WOW! Thanks!
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Post by ThaiGyro on Nov 27, 2017 1:37:21 GMT -5
I too am an old school...do it by hand guy with small bore cylinders. Like 190mech showed, easy enough with household lye...Like easy off. If you don't like chemicals much...simply take some 400 grit, like vert said. Maybe wet and dry paper. (wet) You can make it into a cylinder, stuff your hand...a soft rubber ball, your imagination and work wonders.
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