OzVMX Forum

Clubroom => Tech Talk => Topic started by: Rossvickicampbell on August 01, 2016, 12:09:41 pm

Title: YZ piston
Post by: Rossvickicampbell on August 01, 2016, 12:09:41 pm
Gents - what piston do I have here please?  Sorry - computer problems with loading photos so cannot post direct.

ta

http://i950.photobucket.com/albums/ad349/rossvickicampbell/YZ%20piston_zpscrdknivm.jpg
Title: Re: YZ piston
Post by: pokey on August 01, 2016, 04:56:31 pm
(http://i950.photobucket.com/albums/ad349/rossvickicampbell/YZ%20piston_zpscrdknivm.jpg)
Title: Re: YZ piston
Post by: pokey on August 01, 2016, 05:07:52 pm
Its yamaha soo its a size. 61.958 i believe, what it fits apart from a 125cc is more than this yellow brain can work out.
Title: Re: YZ piston
Post by: Rossvickicampbell on August 01, 2016, 05:20:25 pm
thanks for posting the pic Pokey - and sorry - should of mentioned - it is out of a YZ250A - but not sure on size or type ie is it DT, YZ or MX etc.
Title: Re: YZ piston
Post by: pokey on August 01, 2016, 05:52:52 pm
Sheesh now that dont make sense. the 185 uses a 64mm . most 125s are 61, i think even the honda 750-4 uses a 61 i think.
 why would you put those numbers on if it wasnt a size?
 im sure Ive read  someplace (wossner or wiseco) about the size being written that way in two parts.  Good luck and I will check on the answer as Im intrigued.
Title: Re: YZ piston
Post by: Nathan S on August 01, 2016, 06:16:36 pm
Yamaha 125s were 56mm in ye olde dayes.
54mm for newer stuff (94+).

Ye olde 175s were 66mm.

Photos from the sides would help. From memory:
Anything with a dykes top ring is DT.
Anything with a cut-away intake skirt (as opposed to holes) is YZ.
Anything with little circular intake holes is DT.
Title: Re: YZ piston
Post by: micko on August 01, 2016, 06:23:13 pm
Rosco posted for me, (thanks mate) my plastic verniers say 70mm and its YZ250A.
Inside the skirt says 4310 also says ART and a dot two slashes and a 2 (maybe 2nd over)
Title: Re: YZ piston
Post by: micko on August 01, 2016, 06:24:25 pm
yes has a cutaway nathan