i just got my pr3 pistons today and took a closer look.

reading about how sharp edges can heat up quicker and cause detonation i looked closer to the PR3 stamp and the half inch flat circle in the center of the psiton, the edges were pretty sharp.

is that just a casting leftover or does it have a purpose?
theyre also stamped with 1 on all 4 pistons in that circle.

 

casting mark probably

 

tha circle is power boost, honda didnt put it there for no reason did they?

 

thats what im asking.
to me it looks like a casting feed cutoff
forged pistons dont have it

 

honda also would not waste their money paying for unnecessary labor
like grinding the casting leftovers on every car they produce...
with few exceptions

 

just take some high grit paper and smooth out the sharp edges on the circle and call it a day

 

well i want to make sure i dont ruin the piston by shaving it off.

can someone confirm that its a casting cutoff and not something that supposed to be there?

 

It's just from casting and you don't have to touch it but if it makes you feel better you can lightly sand it down.

 

im OCD about lil details. and belive that every miniscule imperfection


must be eliminated


attention to detail pays off in the end...

 

It's just just a mark from the tooling when they ground the piston. I never take a piston out of the box and just call it good. All edges should be knocked down with some emery paper. You can polish the top of the piston but if you do you should also polish the combustion chamber.

 

well as you can tell from my other thread the combustion chamber looks like a cat was trying to get out of it. so it will be polished somewhat.
im just worried about piston weight once i start polishing it. but i guess i can check that later to make sure they all same weight.

 

polishing a piston shouldn't change it's weight in any way that would matter. If you're grinding things down and changing the weight, you should probably stop as I'm sure the piston is ruined and give the pistons to someone else who knows what they're doing, to look after them for you.

 

why? if i make sure they are all same weight after im done how would that be a problem?

 

if you are going to have your rotating assembly balanced then there would be no need for you to do any weight reduction on your pistons . if you are having your bottom end serviced then that person doing the work will be making all last minute changes. i think what 00Red was trying to say is let a professional worry about what you may be concerned about even if you may be able to match the weights yourself. its better to have an experienced person do certain work just in case there was to be a freak accident while you were trying to do it on your own.

 

well since i wont be ceramic coating them i thought i should just polish them a little then
i dont get happy with dremel so im most certain im not gonna shave off too much.
i read before i do something always, i dont just do it because i think it will work.

this is an image from a website that does polishing pistons

i didnt even go that far.

all i did was shave off the pr3 and the arrow stamps only leaving a slight trace not completely so i dont make a dimple and used the dremel abrasive polishing wheel( brillo pad) to smoothen out the surface and then ran it over with the metal wire polishing wheel.

the shop gonna ballance them anyway. that wasnt for weight reduction either.

 

Make sure to remove material evenly and weigh/balance each piston to make sure they are within spec. Mine are within +/- 0.5 gram. They are +/- 1 gram from the manufacturer.

 

yours came out nice