>> Good morning all,
>>
>> I have a minor dilemma. I am trying to measure the bore of one
>> of my 2 stroke engines (Bullnose) and I have several measuring
>> tools but I don't know the "trick". That is to say that I have
>> telescoping guages, internal micrometer, calipers, and micrometers
>> but in all of that I can't figure out how to insure that the
>> internal mic is in the proper plane for measuring the cylinder
>> bore. As this tool, and the telescoping guages too, can be
>> horizontally and vertically from an ideal plane (which would give
>> max and correct diameter) I don't get the measurements correct. I
>> know this because according to my measurements the pistons should
>> not fit in the cylinders yet they do..
>>
>> .. so how does one really measure the cylinder bore?
>>
>> Thanks all,
>>
>> Lester
On Feb 16, 2007, at 9:18 AM, derf wrote:
> Hi,
> Yes, but when the tool is out of the ideal plane it will give you a
> slightly larger reading.
Exactly my reason for the question..
> Take several measurements and go with the smallest you get. You
> can eyeball a telescoping gauge and get pretty close. The problem
> with measuring cylinders is that they are bigger in the middle than
> at the top or bottom, if there is any wear at all. There will be a
> ridge at the top. Pistons, too, are barrel shaped with a larger
> diameter in the middle than at the top or bottom.
I do understand that but when what I am trying to measure is in the .
08 mm range it doesn't take much being off to screw things up..
>
> You will probably get the best reading with an internal mic. Hold
> one end of the mic against the cylinder wall and open it up until
> it touches the other side without free play. You kinda get a feel
> for it. Do this several times and your lowest reading will
> probably be your best reading. Again, anything out of the ideal
> plane will measure larger. Make sure your inside mic has round tips.
Same conclusion that I came to. But there has to be a better way.
At present, I'm getting it close and then with VERY tiny movements
rocking it side to side and up and down until it will slide through
either direction with a little drag..
>
> Don't be surprised if your cylinders aren't perfectly circular.
I'm just surprised that I can fit a piston that is 70.46 mm into a
cylinder that is 70.42 mm!!! ;-)
Lester
> Cheers,
> Derf
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