Part: Dial Bore Gauge
Why You Need This: If you find yourself getting deep into motorcycle engine building, like on a Honda CB350 / CB360 / CB450 / CB550, then the dial bore gauge is a must have tool to quickly and accurately measure cylinders inner diameter. We use it on cylinders to get a very accurate picture of what condition the cylinder is in. Is the cylinder tapered, out of round or, warped? This will determine if a cylinder should be bored over sized and needs an oversized piston, or simply hone the cylinder and use some new piston rings during an overhaul.
The dial bore gauge must be used in conjunction with the 2-3" micrometer to be used as a setting standard. This gauge measures from 2-6" with an accuracy of 0.0005". The dial bore gauge is in SAE aka INCHES not MM. Historically US is filled with SAE measurement tools as Metric was not a common standard. Honda published the service manual for the Honda CB350 / CB360 / CB450 / CB550 with both Metric and SAE values for easy reference.
We recommenced picking up both sizes of micrometers along with the small hole gauge and the telescoping gauges to complement the dial bore gauge.
Installation Tip: The dial bore gauge must be zeroed using a micrometer. The 2-3" micrometer will cover the Honda CB350 / CB360 / CB450 / CB550 engines. The gauge measures a + or - of a zeroed value to determine the exact diameter of the part. We like to set the dial bore gauge to the service limit of the cylinder diameter and calculate the measured difference. Make sure to remove the dial gauge from the handle when not using the tool as not to load the internal spring more than necessary. This is a precision measurement tool and it should be handled carefully.