Boring a golf cart cylinder

[spope14]

Oh man, one of those jobs I could hate. A former student wants me to bore a golf cart head or him. Seems the auto machinists in the area just want to hone it - he must have gone to ones I do not know....

Need to take .010 out. i know this will probably be one of those time consuming hateful jobs.

Questions...

Bore on a face plate, four jaw or whatever on a lathe?

Bore on a mill with a big old boring bar - not sure I will have the travel.

Have not seen the project yet, how deep does something like this go?

Nothing like a potentially strange job to make you better....

[ibewgypsie]

IF it has any wear at all, it will be rough to get it squared away in the boring bar with just 10 thou to play with.. I had a set of harley jugs egg-bored once.. it used oil and I was not happy.. I took it to someone I trusted next time.

Run the boring bar backwards and leave the cylinder loose, set the bar out till it just touches the cylinder, it will center itself, tighten it down.

Most the boring bar setups I have ever saw was specialty items..

I have tried a couple of times, Playing wiht my bridgy and the criterion boring head.. not done anything I would put together, yet.. I can't get a car motor up on there, I don't have enough overhead.

Doing it on a lathe? that should be interesting, post pictures.. I am sure it can be done.. perhaps a large 4 jaw to grip jug..

Mikey did a harley golf cart, he got his cyl bored at a bike shop, he took his new piston to get it fitted.. (*sometimes it is not the exact correct oversize bore, but a piston fit to make it last)


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[This message has been edited by ibewgypsie (edited 11-11-2005).]

[firbikrhd1]

Not exactly the same job, but I bored a Briggs and Stratton cylinder on my lathe by removing the compound and bolting the block to the cross slide. I used a very stout bar as a boring bar in the headstock and fed using power feed. This particular engine has the cylinder integral with the block so the cutting end had to be unsupported. If your application is more like a motorcycle, where the cylinder is removed from the block, you could make a fixture to hold the cylinder to the cross slide and run a boring bar between centers. Use packing to adjust it to the right height and the cross feed to center it on the other axis (be sure to tighten the gibbs so it doesn't move after it is set up. A dial indicator can be mounted to the bar itself at the extreme ends of the cylinder where there is little or no wear to center the cylinder. Adjustment to depth of cut is made by extending the cutter out of the boring bar a little after each pass. Might be a little trouble to set up, but should work fine.

Dave Gingery uses this method to build one of his machines, possibly when he bores the headstock of the lathe. He made a small tool to adjust the cutter depth accurately. A vernier caliper or micrometer will work too, that's what I used.

[wierdscience]

Only .01"?I usually whip out my trusty Sunnen hone,you know the micrometer type,.01" ain't nothing.

But if your stuck with the lathe I do Harley cylinders that way,just chucked up in the four jaw a dialed in.

You mean he didn't ask you to sleeve it?

[captainkirk]

If you can bolt it to a sturdy plate then center the plate in a four jaw, torque the bolts to the same as the book recomended. Then bore in, reverse the cut direction and pull the bit back out of the bore this will decrease the tendency to have a taper. Don't forget to leave enough material to hone the correct cross hatch pattern for oil retention and ring seating. Use the most sturdy boring bar setup you can devise to keep taper to a minimum.
This method has worked for me in the past your results may vary, as always I disavow any knowledge of ever having done this as the line of kids with motorcycle cylinders that will line up at the door might never end. Swear the student to secrecy when completed, I have found a "blood oath" to work best.

[Pete Burne]

I'll agree with Wierdscience, honing .010" goes real quick.

I bought a Cub Cadet tractor with a 10 HP Kohler engine, pushing oil, real cheap.

Bought a precision hone (actually from Sears, cheap, good quality, never to be seen again). Put the cylinder block on the bench, tied a bungie from the 1/2" drill to the overhead.It was the Home Machinist's version of the Sunnen Hone.

Went .010" oversize in less than an hour. Miked up real good. Runs perfect after 15 years.

Big advantage was that setup was 5 miutes.

Pete

[ibewgypsie]

Only problem I see with the hone method is getting a round jug hole.. If it fits the piston, is round enough it'll work just fine.

That is the reason you start boring, then hone finish.

I have done car motors that way when I was broke... really broke..



[This message has been edited by ibewgypsie (edited 11-11-2005).]

[firbikrhd1]

Just a note on terminology. What some call a hone is really a glaze breaker. There are a few types of glaze breakers, those that are like a bottle brush with abrasive tips and those with two or three stones. If much material is removed with those tools, it is almost certain to make the bore out of round or tapered. A true hone such as that made by Sunnen, or more portable drill powered models carried by Snap-On, Mac, Matco, Lisle and other automotive tool suppliers make round bores.

Following is a link to a true cylinder hone:

http://www.handsontools.com/store/sh...roduct_id=2484

Here is a link to a Glaze Breaker:

http://nationalonlinesales.com/show_Product.asp?ID=775

and

http://www.handsontools.com/store/sh...=2837&referer=
or the brush type

http://www.brushresearch.com/Index.c...oducts/GBD.htm

Note that the advertisements all call them Cylinder Hones, hence any confusion regarding differences is quite understandable.

I apologize in advance if this post is too elementry for some readers. I assume there are those that are quite new to this topic and may not be versed in the differences between the two.

[RobDee]

Here's how I did it.
I made a plate to fit the outside of the cylinder and mounted it to the lathe faceplate with 4 long bolts. This kept the cylinder from being distorted by any chucks.
I then cleaned the top ridge on the bore past where the rings stopped ( all bores have this and it's easy to detect) and dialed it in to zero. Now I knew the cylinder was dead to the original bore. I then checked the outside of the bore to make sure it was square to the faceplate. My first cut in the cast iron was .005". My second cut finished it to size.
RobDee

[Peter S]

There was some interesting stuff posted on this thread.

http://www.practicalmachinist.com/ub...c;f=1;t=006487

Spope,
Actually, I don't understand why your former student didn't let the automotive machinist hone it as offered. I have seen an impressive honing machine at one place for doing engine blocks, largely replaces boring.

One of the good thing about honing is that they will size the bore to suit the piston you provide. Try doing that on a lathe.

My guess is that the lathe is useful when removing a large amount for a sleeve, but not for .010".



[This message has been edited by Peter S (edited 08-25-2004).]