how do U measure the inside of the cylinder to order the right size piston ? i am using a digital calipar but how do u figure in the rings or is that figured into the size ?
need help with piston size
- Thread starter CajunBlaster
- Start date
Best thing to do is take it to the person that will bore the jug and hone it and let them measure it. Most of the time they can get the piston for you as well.
I agree but I don't think I need to bore it out . the rings some reason or another are flush with the piston . Don't know if it over heated or something but all I was gonna do is install a new piston & gasket kit . maybe I should post a pic of it on here also huh ?
The caliper should work then, you'll just be measuring the very top of the bore. A picture is worth a thousand words.
You will need to have it honed so the new rings will properly seat. Measure the diameter of the bore, it will be a few thousandths of an inch larger than the piston
The rings wear the TOP of the cylinder more than the skirt wears the bottom of the cylinder.
The bottom of the stroke wears more than the top because of the rod angle pushing against the cylinder lower in the bore.
The cylinder should be measured in at least 3 to 4 locations top and bottom. More of an even wear will occur at the top due to the steel rings, but the bottom will wear more unevenly due to the sideloading of the crankshaft. Ideally you would use a bore guage to measure the cylinder
you use a bore gauge or a telescoping gauge, measure right above the exhaust port that is where the most wear occurs, never use a caliper for measuring a piston or a bore they are not accurate enough you need to measure in tenths (.0001) and the piston is measured very close to the bottom opposite the wrist pin follow the piston manufacture for clearance unless its a Wiseco, on those you need to add at least .0005 or they'll sieze.
