Cylinder boring

[BogusSVO]

MarkM, The KW-FN is what they call a "portable" boring bar it is designed to lock down with an adapter to a head bolt hole.

It also self centers with a 3 point paw

Now to lay it down on its side may have issues

IIRC it has a max depth of 14 inches, but seldom do I go more than 5 to 6 inches

 

[cdyoung1985]

For what it's worth many years ago, I'm talking about the 70's, I bored the cylinder on my 125cc Honda two stroke. I made a mounting plate that replicated the cylinder mounting flange on the case. Set up the mounting plate in the lathe, dialed in the mounting plate bore, then faced the mounting plate. Bolted the cylinder to the plate and bored the cylinder to size leaving a few thou for honing. I had a local auto machine shop do the honing. Motor ran great.

That might not be a bad idea, do the expensive part, and have a pro finish it...

Sent from my SM-J327P using Tapatalk

 

[patmat2350]

While on words and spelling, you might want to check the meaning of your first post:

"...the stuff is older than that, but in emasculated shape."

 

[BROCKWOOD]

Immaculate = Like new or exceptional condition. Yeah, you would not like what emasculated is.

Interesting discussion, boring out cylinders. I have hopes of graduating to cylinder boring myself!

 

[crazypj]

First cylinder set I bored was a 1966~67 Honda 160 block to take 175 pistons. I think I used a Bridgeport but it was so long ago I forget (around 1974)
Since then, I've done literally thousands of motorcycle cylinders.
I taught cylinder boring as part of 'Clinic 3- Machine Shop' at Motorcycle Mechanics Institute, Orlando for over 3 yrs (so several thousand students) Almost everyone could bore and hone a cylinder to within specification of +/- 0.0002" by the end of 3 week course (at least all my classes) The problem with boring on mill is lack of quill travel which is usually 5" or less. A lathe can sometimes be much more useful if you have a large enough bar. It would be better to make something that will bolt on in place of tool-post and take a 'spring cut' or two before honing, Bar should be 2~3" steel to give greatest accuracy, use croos slide to set cut. The KLR cylinder doesn't need torque plate, do you mean to bolt it to a face plate? If your not familiar with using DTI it can be a pretty frustrating experience to get things centered up properly. As for poster who said torque plates probably aint needed, correct but some engines MUST use torque plates as they 'distort' the cylinder to fitted shape (Harley Davidson 'Evo' cylinders distort around 0.001"~0.002", center gets 'smaller' when fitted if torque plates ain't used) You will need a rigid hone (Sunnen, Ammco, etc) to finish size cylinder accurately, the 3 leg spring hone won't work to remove any out of round or out of parallel. You'll also need a bore gauge, the cheap $50.00 ones are not worth the money, you need 0.0005 " resolution minimum, 0.0001" is way better (and 'only' about $175.00 more expensive)
Initial set up may be substantially more than paying to have bore done but it will repay investment many times over when you start doing modifications (swapping cylinder liners, 'big bore' kits, etc) I would probably try and find KLR300 piston spec to see if it could be fitted into 250 cylinder.
As for doing 883 Harley, no idea how many students did their own before HD stopped supplying pistons (hundreds of $125.00 piston kits instead of $800+ piston/cylinder kits) You have to remove 0.495" from bore to go to 1200cc, makes cylinders a LOT lighter. Modified 883 head is actually 'better' than stock 1200 head, there is enough material to make ports a much better shape and size (and way cheaper than buying Buell 'Lightening' parts)

 

[crazypj]

Oh, if your a bunch of fabricator weldors, you will probably have access to all sorts of steel 'offcuts' to convert into useful tools. 'Grinder and paint made me the welder I am today LOL

 

[cdyoung1985]

First cylinder set I bored was a 1966~67 Honda 160 block to take 175 pistons. I think I used a Bridgeport but it was so long ago I forget (around 1974)
Since then, I've done literally thousands of motorcycle cylinders.
I taught cylinder boring as part of 'Clinic 3- Machine Shop' at Motorcycle Mechanics Institute, Orlando for over 3 yrs (so several thousand students) Almost everyone could bore and hone a cylinder to within specification of +/- 0.0002" by the end of 3 week course (at least all my classes) The problem with boring on mill is lack of quill travel which is usually 5" or less. A lathe can sometimes be much more useful if you have a large enough bar. It would be better to make something that will bolt on in place of tool-post and take a 'spring cut' or two before honing, Bar should be 2~3" steel to give greatest accuracy, use croos slide to set cut. The KLR cylinder doesn't need torque plate, do you mean to bolt it to a face plate? If your not familiar with using DTI it can be a pretty frustrating experience to get things centered up properly. As for poster who said torque plates probably aint needed, correct but some engines MUST use torque plates as they 'distort' the cylinder to fitted shape (Harley Davidson 'Evo' cylinders distort around 0.001"~0.002", center gets 'smaller' when fitted if torque plates ain't used) You will need a rigid hone (Sunnen, Ammco, etc) to finish size cylinder accurately, the 3 leg spring hone won't work to remove any out of round or out of parallel. You'll also need a bore gauge, the cheap $50.00 ones are not worth the money, you need 0.0005 " resolution minimum, 0.0001" is way better (and 'only' about $175.00 more expensive)
Initial set up may be substantially more than paying to have bore done but it will repay investment many times over when you start doing modifications (swapping cylinder liners, 'big bore' kits, etc) I would probably try and find KLR300 piston spec to see if it could be fitted into 250 cylinder.
As for doing 883 Harley, no idea how many students did their own before HD stopped supplying pistons (hundreds of $125.00 piston kits instead of $800+ piston/cylinder kits) You have to remove 0.495" from bore to go to 1200cc, makes cylinders a LOT lighter. Modified 883 head is actually 'better' than stock 1200 head, there is enough material to make ports a much better shape and size (and way cheaper than buying Buell 'Lightening' parts)

Ton of great knowledge there, thank you!