help needed anyone with late modle wr/yz250 piston/knowlege

[twinrock]

hey guys im after anyone with a wr250 or a yz250 piston for comparison..i have a big bore banshee engine which i need to replace a piston at 69.50mm and i can not find any any where..i have read and beed told that wr250 and yz 250 can go out to this size also..so i would like to compare the rest of the pistion ie deck and gudgen pin hight etc thanks alot my piston measurements are 69.50 diameter top of gudgen pin to piston edge is 27mm gudgen hole size is 15mm 2 windows at the rear of piston are 17mmx17 thanks alot any help would be great thanks..

[jimg1au]

hi
can you give me some part no so i can check against zedder yamaha part no
also wiseco have a 69.5 piston and rings for a
Tri Z 250                68 68.00 515M06800 $150.53 2677CD S511 W5493 B1014
Pro-Lite x                68.50 515M06850 2697CD 1985-89 $16.75
Liquid Cooled 68     69.00 515M06900 2717CD CW18 $37.95
69.50 515M0          6950 $165.59 2736CD
70.00

[twinrock]

hey mate thanks alot..this may be very close..unfortunately the piston i have has no number or anything..i have no idea of knowing what it is..hence half the problem..there for my only option is physically comparing it with something else any one know the gudgen to piston crown measurement for a tri-z 250

[evo550]

I've got an '04 YZ 250, I'll check for you over the weekend.

[jimg1au]

twinrock
you can tell me the year and model of your bike i can look the part no up on the yamaha web page in theusa and then check zedder
cheers

[twinrock]

ok the problem is that my bike has been fitted with an after market big bore sleave..which makes reference to the original engine specs not really applicable.. but the engine is rz/banshee 350 1983-2000 aprox standards bore size goes to 64-66mm stroke 54mm  mine has a sleave which starts at 68mm and is currently at 69.50..so it seems obvious that they have just used another piston from another bike for this application as i doubt they they would make a piston just to cater to a custom sleave, but rather the other way around design a sleave with a piston that is already available...i just need to find that piston. all your help is very much apreciated..

[Freakshow]

Sounds like a US kit, have you tried emailling them its probally an off the shelf kit.  there ar e a few banshee wreckers listed on ebay so email one of those parts sellers they would sure as hell know, if the piston has those grooves in it , its after market and sure as eggs it will be Ex USA.  Go to the source.

[Tim754]

This mob ATVunlimited  on eBay has heaps of new Banshee and ATV piston kits and stacks of other stuff   . Here is a 2.25 over bore kit for 350 (  360030602706 ) , go there and dig around you may find your 250 kit. Cheers Tim

[twinrock]

this is the frustrating thing...out of all the u.s banshee companies ive tried no one stocks a cast piston at this size...even the company who makes/supplies the sleave used in my barrels..!!!! very annoying..i can get wsm forged pistons at this size but that would require 2 complete new pistons and probably a rebore each side to alow the differences in the forged tolerances..i have even tried to contact the guy i bouth the top end off but he has not returned..i have since found a supplyer in aust serco ..but they want $260 for one piston.!!!..not including the rings or lil end bearing..!!! and they wont tell me what other bikes if any it runs in,,oh well back to the drawing board..!!