bike had a meltdown and now i am having a meltdown.
brought heads and cylinders into bike shop.they say it needs to be bored to 30 over.its 10 over now.there was some alum piston material onto the cyl wall but i felt no grooves or pitting or anything like that.---shouldnt i have been able to feel some type of groove to make it nec. to bore to 30 over? i was planning on doing the bare min. but if its gonna be bored out to 30(and valves replaced most likely they said) should i do anything else?
also how many people here does their own machine work?i pretty much never take anything to a mechanic...i always leave disapointed everytime.i am not so great in math and i have no machine shop tools but from now on i will be keeping my eyes open for them.i know i can do it.---what do i need and how much will it cost?i found boring machines online for around $1300.is that the going rate?
its basically gonna cost about 600 bucks...possibly less(yeah..ok whatever..well see...its like feeling good about 3.80 gas instead of 4.00) i think about half lab. half parts.

 

To determine how much you need to bore depends on how much out of round the cylinders are. It is quite possible it would take 30 over to clean it up. You could measure it yourself and decide. Six hundred for boring and a valve job is awful high, especially since you did the disassembly. The last time I had cylinders bored it was $50.00 a hole. Unfortunately that shop is out of business now. Tools for cutting valve seats are expensive, about 750.00 from Neway.

 

The amount the cylinder needs to be bored oversize is determined by measuring the cylinder bores at the top, at the mid section. and at the bottom (where the cylinder rings never reach)
Then measure the same points in a plane 90° to what was just described.
This gives you the answer to how egg shaped is the cylinder is and how worn the bore is.
Pistons come in size increments. So if your current bore is worn out, the minimum re-bore will be the next piston size up. On a really bad cylinder you may have to jump up 2 sizes.
It all depends on how they measure out. A piece of stuck piston on the cylinder wall almost guarantees the next size up (minimum) is needed without even measuring the bore.

Regarding home machining.......Almost nobody does this other than a business that does auto machine work, and even then the place may send the cylinder out for boring. Most good motorcycle shops containing a machine shop operation can handle the boring in house.

Take me as an example....I have....
quite a bit of ironhead knowledge, most of the tools known to mankind, a Bridgeport milling machine, a South Bend lathe, and the 3 phase power to run everything.
I mill, I do lathe work, spin wrenches etc, but I would never kid myself about boring my own cylinders, grinding a crankshaft or something like that. It takes special tools and special knowledge to accomplish those tasks.
I currently have a 350 Chevy engine block and crank at a machine shop that builds nothing but race engines. I was surprised when he told me he does not grind cranks, but everything else is done in house. This shop just does not have the tools to do cranks.
Reason they don't is because of the huge capitol investment required.

So it sounds like you will need:
Re-bore with new pistons and rings
All of the associated gaskets and seals

You may also need:
Refacing valves or new valves
Valve seats ground
New valve springs
Valve stem seals
Valve guides replaced
This 'may also need' list will be determined by the amount of wear.
That about covers it.........pg

 

the $600 was for basically everything..gaskets,pistons,rings as well and she said she was tyring to guess on the high side.she didnt have the exact amount because i showed up after about a week without them calling me.i think they have a machinist that comes around and does the work in house.she is very knowledgeable though but she was much cuter before she started quoting prices...
pinion i am surprised and humbled that you wouldnt rebore a cyl yourself.that makes me feel quite a bit better.what exactly about reboring that you dont feel comfortable with?also they told me there was no valve stem seals in the head....that harleys didnt come with them but they make aftermarket seals....some people use them some people dont?????? have you heard that before?

 

My 72 didn`t have them

 

Valve stem seals were an option on cast iron heads (knuckles also) Those cast iron heads needed a good amount of oil to lub the valve stems (lots of heat) Plus the seals can come off the guides even if installed correctly

 

ok no valve stem seals.-----does everyone feel the same?

 

I've done my top-end with and without valve guide seals.....Anymore I go without the seals.

 

SD13.......
It's not so much being comfortable with it as it is not having the proper equipment.
My Bridgeport could do the boring, all it takes is a boring bar (which I think I have) and setting the cylinder onto the mill's table exactly vertical. I have the measuring tools to do that.
The cylinder is first bored using a boring bar.
The particular piston to be used in a particular cylinder is first pulled out of it's box and measured carefully.
Then mark it for the cylinder you are going to bore.

No two pistons are made to the same exact size due to std manufacturing tolerances, be it a motorcycle, automobile or lawn mower piston.
You bore the cylinder oversize to the same exact measurement as that new piston you are holding in your hand.
The final clearance needed is .0025 larger than this for the finished diameter. This is achieved by using a hone, such as a Sunnen or some other brand.
This important piece of equipment I do not have. That is the reason I would not attempt to bore it myself.

The Bridgeport cost me close to $5000 by the time I got it sitting in the shop.
I have no reason (nor money) to buy a Sunnen Hone. It will do only one thing....hone a hole to size.

Along the same line.....You will need a valve grinding machine if you want to reface your valves. I do not own one of those either. I almost bought a used Sioux for $600 a few years back, but after giving it some thought I decided I would not use it enough to justify the cost and especially the floor space it would take. Like the boring, this is something that is better done by a shop that has the equipment.

Do not think getting something back from a machinist is going to be like getting something back from a mechanic. World of difference! A mechanic is prone to be lazy and sloppy. A machinist is just the opposite for the most part.

As to my mention of the valve seals, I only did so because some folks like to use them. I do not and never have. Harley never installed them on an ironhead.
Proper clearance of the stem and guide bore are what keeps oil from running down the stem. The specs for that are....
Exhaust= .0025 min to .0045 max
Intake = .0015 min to .0035 max.........pg