Engine compression tester

[dbelanger24]

So my motor has been giving me trouble starting and I've changed the spark plugs but while I put back together the recoil I figured I'd order an engine compression tester. I'm not sure what size fitting it needs for the engine. some of the kits I've looked at the fitting are marked by the sizes M10, M12, M14, M18 which i'm assuming the "M" stands for metric. That being said how do I determine what my engine takes for a fitting??

There is no indicator of size on the spark plug that I can see.

here is a list of the compression testers I am looking at

https://www.ebay.com/itm/Cylinder-C..._Automotive_Tools&hash=item2c6de03550&vxp=mtr

https://www.ebay.com/itm/Engine-Cyl..._Automotive_Tools&hash=item1c282dcf51&vxp=mtr

yes they are kits but I figure I may need to check compression on other motors down the road.

 

[SumDumGuy]

If you go to this site ... https://www.sparkplug-crossreference.com/
you can get spark plug dimensions.

Also, do you have a harbor freight near by?
This is the same kit but cheaper.... https://www.harborfreight.com/compression-test-kit-66216.html