MX360A piston and Ring

[Rossvickicampbell]

Jim - I ask why though as the pistons I see have them in the same place and one is running correctly in my bike currently?

[jimg1au]

i uderstand that it is running in your bike but if someone else has a problem just reposition the pin.i have 2 cr250s the pistons wont interchange as the porting is very different
cheers
jim

[Freakshow]

CG  - Beware of saying RT's as you will find some will be for the Piston port,  with out the window.

Only for RT1's 

Exsacary.............  but you'd be surprised  CG, some folks just buy an Rt not knowing the differance. MAybe im stating the obvious sorry.

Got your PM, Tossa.  checked  All my Wiseco stuff is P2 -P8, but i do have Genuine YAmaha piston and rings (96) but you'll probally get them quicky off Rossco if you need em before the weekend.

On another note i have some RT1 Pistons i will never use open to offers with a few sets of matching Dykes ring sets. 

Also found a  pre 71 TS250 - RH67 piston in the Stash if any one's looking for one of them.

Rosco - you can use the MX or YZ 76-78 pistons so long as its the right ring set  it makes no differanc so long as the ring sits on the pin right ( ie under side or overlaps versions)

[Rossvickicampbell]

Jim - no dramas but this is where I am confused - if I have two types of pistons ie MX and YZ which fit my YZ how can they not fit another (supposedly) standard YZ?  Why would somebody need to move the pin?

Freaky - thanks - I am just confused over this comment that pistons that fit my bike have pins in other places but are for the same bike - is that clear?? 


AAAAAAGGGGGHHHHHHHHH!!!!!

nearly beer o'clock here!

[jimg1au]

the reason you need to move the pin is when it pin goes into a port.you move the pin to the left or right to make sure the barrel liner and pin have full contact all the way through the stroke.if the pin goes into a inlarged port it will catch and a rebuild will be needed.
lozza could explaine it better,
cheers.
jim

[Lozza]

Not quite right Jim, many many pistons are pinned on centre at ther rear running through the boost port, no problems.Some are pinned to run on the septum between the auxilary transfer and the boost port(if there is one).Only time problems seem to arise is where the gap in the ring is close to the edge of a port.

[jimg1au]

thanks lozza i thought you would correct me where i was not right
jim

[Tossa]

Isn't it amazing, a thread about a simple request to find a part can out such knowledge about the whole thing, am picking up heaps of info from you guys.  the things we do to make things work.  the motor I have had a Honda odyssey piston in it with a 1 mil alumium gasket at the base of the barrel and worked wonderfully well.  Work was done by the late great dean (Doc) harrison. 

Barry

[Rossvickicampbell]

Gents - I understand what you are talking about - no dramas there.  But.....................my question still remains - why will an MX/YZ piston that fits my YZB not be suitable for another YZB or is it just somebody being overly cautious although how is it they can then buy a piston for this bike with the pin in another place.

Lozza - if you look at my pistons rear to front the pin sits slightly left of centre - the MX piston has the two windows whilst the YZ piston has the cutaway.  I am not sure where the pin in the "other" piston is but can find out?

Might try and get some photos.

Rossco

[Lozza]

Is the piston single or twin ring? Twin ring pistons tend to be pinned on the side and run between the transfer and boost. A piston is a piston they go up and down that's all Window's v's cutaways  make no real difference except maybe to longevity of the piston, I would go for the window piston over a cut away and a full skirt as first choice.

[Freakshow]

Ross, your doing your own head in.

The MX and the YZ piston wether windowed or Moon cut fit. They all interchange and it dont mean shit what version of YZA or B ( some DT1) it is it will fit, if its the right ROD, the bike will still run the same and the sky wont fall down.

IF someone has issues over a pin then they can waste there time and move it, grovve it or shampoo it, for my time=value Ratio i would suggest they spend more time Rebuilding there forks to find speed, if its purely a fear factor then they should spend there time chamfering there port windows properly so there is no chance of ring catch.

FWIW - the 360mx piston is roughly inline with the piston left window, which means it travels across its own standard barrell port window, thats how it was designed and i have not heard of anyone having an issue infield.

[Rossvickicampbell]

nah Freaky it isn't that bad - and you guys are just supporting my thoughts and those of the guy who put my motor together with the MX piston - other than windows or cutaways they are the same - however have you heard of a YZB piston with a pin in another spot?  I have asked this gent where the pin is different compared to the piston I loaned him and this is where I am interested in how it could be in another spot and why?

Lozza - single ring thats all.

thanks for the thoughts - I am like Tossa every little bit helps the knowledge bank.

Rossco

[Freakshow]

probally dont matter where the piston pin is on the old piston you took out, could have been a miss shot or even another non genuine or product shift ( another supplier)

both the MX piston you have has a pin on the left and the replacement Wiseco 234 double ring has a pin on the same left side, so i cant see any reason why you should be worried about what you have in there, if anything maybe the one that was in there was the odd one and its better its out.  I would only worry on a pin on the ext. thrust side , thats where all the forces are and the big port edges