250r piston

[trx]

will i took the head off the other day and i found like a small hole on the top of the piston on intake side on the right it looks like a 3 quater moon shape like a pin hole kind of ,,the motor is a 85 atc250r and this piston is huge compared to my old trx250r piston it looks way bigger with a flatter top and the skirt is thinner this is the first time i took the head off and looked to detail so i know its bored and its a different piston for sure and the the reed intake has a small port too it

this motor was built back in the 80's and my dad wasnt to sure what was done too it all he had the motor built by a guy

so what is this pin hole

[trx]

heres a pic
and the hole doesnt go throw all the way ethier i didnt find no metal in cylinder or tranny oil and skirt is fine no scracthes or scraps or scuff marks on that side

[honda250r]

i think that is supposed to be there it doesnt go down deep does it

[trx]

Originally Posted by honda250r

i think that is supposed to be there it doesnt go down deep does it

about 2 cm deep and its a perfect 3 qauters moon shape

i thinks its a cooling chamber of some type to lube the wristpin and the inside of the piston like a boost port

[honda250r]

i have never seen that before

[trx]

i have no clue what it is theres no words or arrows on the crown at all theres no IN like the trx piston its a solid flat top piston it has a slight crown but not as much as a stock one

[250rrunner]

well my dads say, if it works dont mess with it.

[pimpt250r]

the top of the piston shouldnt have any flaws ,,
4 pokes do though