YZ360 pistons

[Rossvickicampbell]

Ladies and Gents -  chasing pistons for either YZ360 A/B - std size.  Anybody hoarding any out there?  Have found my last one is out around and therefore not much good.

thanks

Rossco

[OverTheHill]

http://www.ebay.com/itm/YAMAHA-NOS-VINTAGE-PISTON-YZ360-STD-1974-75-432-11631-01-98-/351462758780?hash=item51d4d0197c

Here's a std piston for the next model but chances are they're all the same so long as the ring peg misses the boost port as were pretty wide on those by memory. Same 80mm bore on all the 360's & don't think the gudgeon height altered in the pistons. you say yours is out of round but they 'are' mean't to measure smaller crossways as opposed to for & aft, but maybe that's not what you meant?. If you needed to bore it, originaly the A & B only went to second over [0.50] with a thin original sleeve but if you've re-sleeved it with a thicker sleeve then [on my old RT2 & 3 rat bikes i'm using 2X5 piston kits which is 82mm std, YZ400F 1979 [only] long stroker smaller bore 400. Need about 5mm off the skirt to be safe at BDC as gets close to the flywheels but in saying that i forgot to shorten my last one [now i'm worries] still going well though. Head needs to be machined out slightly to clear 82mm of course. Not sure if that helps but there ya go--just me woffling on lol.

[Rossvickicampbell]

thanks OTH - info much appreciated.  This piston is an oversize one - 98 - I am chasing a 96................so can keep looking.  And bloody expensive - wow!

[Rossvickicampbell]

bump'n it up 

[Davey Crocket]

Geez Ross, there's 100's of them on evilbay.....just type in Yamaha 432 piston and you will find them from $99......If your putting it into a bore that you have already run then you will probably want the .98 piston, the .96 was for brand new bores ...there's only .02 diference. Get it measured and buy a spare one. I have been looking for a std 250A piston for 3 months....everywhere....they have dried up for some reason.

[Rossvickicampbell]

you must be looking somewhere different to me DC or you are seeing things- lots of MX ones around not too many YZ ones - and I aint paying over $200 bucks for an oversize one I don't need yet.  And no harm in asking around.  One piston listed at $99 plenty others again oversize at $195-$199 USD. 

There is an O/S 250 one there - you could always bore out to suit 

[GO49NC]

There is two 360B pistons i can see on ebay us.One for $99.99 and one for $129.99, both 96 pistons. 

[Davey Crocket]

The .96 and .98 pistons went in the same size bore Ross....they measured the bore at the factory when machined. The.98 is not an oversize piston so to speak. Modern engines have A B C  size pistons to use as you get that little bit of wear so you don't have to buy a new barrel or get it re-nickosiled . The $100 and $130 pistons are cheap, even the post.

[Rossvickicampbell]

aaah - learn something new everyday - thanks John - thought 98 was oversize.

[GO49NC]

Ross,the 96 98 thing is what TZ road racers also had, due to chrome bores

[yamaico]

They were called fractional oversize pistons and you could get them for just about any Yamaha in the seventies. Same rings (std), just fractionally bigger piston.

[Freakshow]

email me id have the 360 and the 250s somewhere, can they be used ?