Piston condition

[Angus McL]

Pulled the top end off yesterday. I'm pleased overall with what I've found so far. Cylinders are very good. I'll pick up proper bore gauges this week, but measuring with verniers, they are bang on the spec in the book (2.520"). There are a few pits in the wall (can just barely feel them with a fingernail) so I'll send them out for a light honing and see how they look after that. Some very light scoring on the intake side of the pistons (again, can just barely feel them with a fingernail). Exhaust sides look fine. Combustion chambers in the head look like shiny and new - not lean burn down shiny, but clean, bare aluminum like some one cleaned them up and then never fired the engine back up.

I'll put new rings in when it goes back together (along with the jugs being honed), but what are the opinions on the pistons? Re-usable with a little bit of emery cloth?

Thanks,

A.

[evan_calgary]

Pistons look fine to me. There are likely some better opinions here though that will chime in and help out.

[silverstrom]

New pistons and new rings along with a fresh hone. Good for another 20,000 km and no worries. Putting it back together with old piston and rings is, as they say, false economy. You're already there. Do it right.

[hondaror]

I'm with John, new new hone. I don't like the look of the skirts on the intake side, or the bore. Measurements tell more tales.

[Bare]

Dunno... A hone aggressive enough to eliminate the apparent in the photo showing bore wear/damages will be unlikely to retain adequate piston/bore tolerances.
Assuming that they are even close 'as is'
Remembering that 1 thousands off spec is a *Problem* and that even the Yama oem spec is a bit 'loose'.
Depends entirely on how long you want to keep it though.

Elephant in the Room issue with these 350s is that they have only Two conditions:
A) in need of a rebore
B) just had a rebore

[Angus McL]

Are Banshee rings ok to use in an LC? Did the Banshee have iron or Nikasil bore liner?

A.

[Bare]

Gotta use OEM rings on oem pistons. Besides that, OEMs are the best quality.
OEM Banshees 'should' fit decently.
Others may fit correctly OR may not.. risky. Not all bits from 'other' sources will intermix with 100% assurance.
Again; Rebore and fit New pistons/ rings... it's necessary.
The rebore shop (IF competent) will require the pistons to bore the holes to match them to.. within the Yama Factory spec.
Bore/pistons (and Cranks to a lesser degree) are NO place to economise.
It will Bite you... expensively.
PS: Slinger is in your part of the World... PM him.

[nzminis]

If it was my bike and i was planning on keeping it
I just rebore with cast pistons and be done with it

then you know where you stand

[Angus McL]

Looks like a bore job it is! Got out the feeler gauges today... Can get a 0.004" in everywhere and 0.005" in here and there. Book says 0.0026-0.0028", so decision made!

Will go Yam Pistons if I can find them in first oversize. So what's my best bet? 31K, or Banshee?

A.

[hondaror]

RZ OEM pistons are no longer available in any size.

[Angus McL]

Well that makes it easy then!

A.

[hondaror]

A buddy works for YAMAHA Canada, and all engine pieces are still available except pistons. Many of the dealers will tell you otherwise.

[nzminis]

Mitaka (prox same thing )
tkrj
are good brands
31k and banshee both work

[silverstrom]

FYI...my sources tell me that Mitaka are made by ART, supplier of OEM pistons.

[2smoke]

Mitaka (prox same thing )
tkrj
are good brands
31k and banshee both work

X2

or these are easiest, plug +play:
http://yambits.co.uk/rd350lc-piston-kit ... 53898.html