Flex hone question

[blasDa]

On the website for the flex hone manufacturer, they list a 67mm flex hone, but for all the Canadian distributors websites, they jump from a 64 to a 70 and they say to choose the next bigger size of the bore.

Would I be ok using a 70mm hone for a stock 66 bore? How much flex is in a flex hone? If I have to special order a 67 from the states, it's gonna cost me almost double. Yikes!

Also, should I get 240 or 320 as a finish grit?

 

[MURPH]

i heard that using those flex hones with the balls like this isnt good for 2 stroke cylinders cuz it catches on the ports


i was told to use ones like this

 

[OConnor Racing]

Murph is on the right track but do this. Get the three stone hone and some 280 grit wet / dry sand paper. Cut a sheet so it's a 2" longer than the stones and overlaps the bore. Shoot the cylinder and the paper with WD-40. Connect the hone to a variable speed drill and place the paper into the bore. Place the hone into the bore so it contacts the paper. Move the hone up and down at a slow speed to achieve a 45 degree cross hatch pattern. Don't be concerned with taking a bunch of material out. This should take less than 10 seconds. When you're finished, if you still see bare spots inside of the bore. You need to have the cylinder bored.

 

[blasDa]

Sounds good. Thanks guys!

Ken, I really appreciate all the videos you've made and all the tips you offer us do-it yourselfer's.
I will be placing an order for a porting template, & some other small stuff very soon.

I took a bunch of measurements on the cylinder with a telescoping gauge and mic. It seems to be straight, round and on size (66m) within .0005, so I'm hoping a quick hone will add cross hatching, & remove the glaze, & very slight surface rust, without having to bore it. I don't have a boring machine, just a universal mill and a boring head (& a cheap one at that lol). I'm sure I can rig something up if it has to be bored though. I also managed to find a spare cylinder, so I can screw up a cpl. times, if I have to. Lol.

 

[OConnor Racing]

Glad to help Boss. You don't need a half ass engineering degree to do this. You're better off without one. Best advise I can give you is to keep all of the parts you assemble surgically clean. Dirt from your hands and oil = lapping compound. I know it sounds pretty simple but common sense is the best procedure.

 

[blasDa]

Thanks again Ken!

No half assed engineering degree here lol. I'm a plastic injection mould maker by trade. Have built moulds, dies, automotive checking fixtures, & now am a millwright / die setter for a company that manufactures racking and shelving. So I know a lot about machining, but nothing about engines. That's where all the helpful advice I'm finding here comes into play. Tell me what needs to be done, & I have the skills and equipment to make it happen.

I'll end with a joke your comment reminded me of....
What's the difference between an engineer and god?

God doesn't think he's an engineer.

 

[OConnor Racing]

That's funny man.