TRX250R.ORG

Workshop => Engine and Bottom End => Topic started by: evaneyeball on March 31, 2020, 07:37:08 PM

Title: what piston is this
Post by: evaneyeball on March 31, 2020, 07:37:08 PM

i took this out of my 86 trx250r motor and i asked on the .net forum and only one person responded and said its a yz250 piston and i dont 100 percent believe him. but just want to clarify if it truly is a yz250 piston or just a trx250r piston its a pro-x and is stamped with 150 on top so its 1.5 mm over and ive googled it and have come up with nothing. im not putting the piston back in so its no big deal and if it is a yz piston what do you think its doing in a trx250r

Title: Re: what piston is this
Post by: croat1 on March 31, 2020, 08:26:29 PM

YZ pistons start at 70mm

Title: Re: what piston is this
Post by: evaneyeball on March 31, 2020, 08:34:11 PM

from wiseco from 1999 to 2015 the stock bore is 66.4. so it could be, or am i wrong

Title: Re: what piston is this
Post by: The norm on March 31, 2020, 08:57:44 PM

A yz piston is used when bore size gets past what's available for trx250r's

Title: Re: what piston is this
Post by: evaneyeball on March 31, 2020, 09:03:19 PM

So you dont think that this is a yz250 piston

Title: Re: what piston is this
Post by: broken1 on March 31, 2020, 09:40:02 PM

Looks like a short rod R piston to me, however I have never seen a YZ piston so I'm not sure if they look identical to the R piston or not.