Author Topic: Engine re-bore measurement tool ????  (Read 1523 times)

0 Members and 4 Guests are viewing this topic.

Offline Toxic

  • Expert
  • ****
  • Posts: 1,200
Engine re-bore measurement tool ????
« on: February 19, 2010, 11:43:33 AM »
So I am looking for a bore gauge to measure the bore on my cylinders to see if I need a re-bore.  What are you guys using to get an accurate measure.

I found a dial bore gauge from Eastwood but I am questioning the accuracy of a dial gauge.
As opposed to a digital gauge.

I know I need something accurate to 4 decimal places.

I have a digital micrometer but that will only get me a reading on the top and bottom of the cyl.

Does anyone have any useful links?

thanks Gary

Offline MRieck

  • Really Old Timer ...
  • *******
  • Posts: 10,566
  • Big ideas....
Re: Engine re-bore measurement tool ????
« Reply #1 on: February 19, 2010, 11:51:06 AM »
Mitutoyo are good. I use an older SPI. You will also need a decent mic to index the bore gauge.
Owner of the "Million Dollar CB"

Offline Toxic

  • Expert
  • ****
  • Posts: 1,200
Re: Engine re-bore measurement tool ????
« Reply #2 on: February 19, 2010, 12:44:43 PM »
ahh so I learned for my one time use I am better off to take the cly to a machine shop and pay them to do it.  Those guages are expensive.  And there is no point in getting a cheap one.

good to know

Offline Bodi

  • Really Old Timer ...
  • *******
  • Posts: 5,697
Re: Engine re-bore measurement tool ????
« Reply #3 on: February 20, 2010, 03:26:14 AM »
Direct reading dial gauges are not accurate enough. You can get an idea of round vs oval holes but not exact measurements.
The accurate way is using bore gauges, you insert the gauge and lock it so it stays the length equal to your bore, then measure it with a micrometer.
The gauges each adjust to maybe a 1/4" to 1/2" range and most micrometers have only a one inch range. The gauges come in sets but I suppose you could buy just the one you would need.
There are also horridly expensive accurate direct measuring bore gauges.
Unless you have a machine shop there's no point in owning this stuff, really. Have an expert measure the bores. This will cost a pile less than buying the tooling to do it yourself accurately.

Online bryanj

  • Really Old Timer ...
  • *******
  • Posts: 14,044
  • CB500 Number 1000036
Re: Engine re-bore measurement tool ????
« Reply #4 on: February 20, 2010, 07:58:59 AM »
I Bisagree Bodi I have a dial bore gauge that goes down to 1/10 thou increments. Set an accurate mic to the bore set the bore gauge to zero using the mic then use the bore gauge in the hole, If you set the dial to zero when the small needle is at 1-2mm you can then get accurate hole readings as below zero
Semi Geriatric ex-Honda mechanic and MOT tester (UK version of annual inspection). Garage full of "projects" mostly 500/4 from pre 73 (no road tax in UK).

Remember "Its always in the last place you look" COURSE IT IS YOU STOP LOOKIN THEN!

Offline MRieck

  • Really Old Timer ...
  • *******
  • Posts: 10,566
  • Big ideas....
Re: Engine re-bore measurement tool ????
« Reply #5 on: February 20, 2010, 11:18:55 AM »
I Bisagree Bodi I have a dial bore gauge that goes down to 1/10 thou increments. Set an accurate mic to the bore set the bore gauge to zero using the mic then use the bore gauge in the hole, If you set the dial to zero when the small needle is at 1-2mm you can then get accurate hole readings as below zero
That's how I have always done it. My gauge goes to tenths too
Owner of the "Million Dollar CB"