87 warrior

[scoot1073]

New to site, but have been reading and looking over all the excellent information shared here.:tup: What I have is (I believe all original) 1987 warrior I'm rebuilding.

Few Questions:
Does this look like the original piston?


Why would there be three head gaskets?


Before a little elbow grease.


After.

Any and all help would be greatly appreciated.

 

[Warrior1996]

That looks like the original piston to me, but I'm not 100% sure on that. That head gasket you have is stock, it's a three layer metal design.

 

[bomber315]

that is definitely a Yamaha piston with that 1UY marking, tho it maybe over sized since it says "50" .50mm translates to .020in overbore.

as far as the head gasket, that is all supposed to be stuck together as 1

 

[scoot1073]

That looks like the original piston to me, but I'm not 100% sure on that. That head gasket you have is stock, it's a three layer metal design.

Thanks for the quick reply. Yeah, I'm pretty sure its all stock. I bought it off my sister and she owned it for 20 plus years and it sat in her garage most of it's life.

 

[scoot1073]

that is definitely a Yamaha piston with that 1UY marking, tho it maybe over sized since it says "50" .50mm translates to .020in overbore.

as far as the head gasket, that is all supposed to be stuck together as 1

Thanks. I'm taking the head and cylinder to work today to mic everything so I'm 100% sure on size before ordering new piston.

 

[scoot1073]

I believe this is the piston I have. .50 Piston 1UY-11636-01
http://www.ebay.com/itm/New-NOS-87-...ver-Size-50-Piston-1UY-11636-01-/360865226580
Should I order another one like this or get it bored and honed for the next size bigger? I'm thinking about this kit.
http://www.ebay.com/itm/YAMAHA-350-...-04-/221891919304?hash=item33a9c9fdc8&vxp=mtr
What would be the best way to go about this? Bigger, same, honed, bored. What would you do?

 

[hammy7734]

i would put a after market piston in it like a Wiseco or a JE but i have a stock bore Wiseco 10:25-1 and i love it

edit: i would keep it the same size it is now if you can

 

[Warrior1996]

You need to definitely at least hone it. Ideally, you take it to a machine shop that will check to see if the cylinder is still within spec for the piston you want (or you can do it if you know what you are doing, it sounds like you do). If it is in spec, hone it and you're good. If it's not in spec or is out of round, you will need to bore it until it is round and within spec for a larger piston, and then hone it. Only go as big as you need to to make it round and smooth, boring it out larger will not gain you any more performance. If you are chasing performance, this is a good time for a high compression piston, like JE or Wiseco. If you are just looking to rebuild it stock, then an OEM style piston would be fine.