identify this piston ?? clearance ?

[lee37vernon]

i got this piston with a 330 pro x barrell . being told its a wiseco , however it's cast so must be another make . it looks like either the boost hole on the inlet side has been cut into it , or made larger . i just want to know which .
the numbers on top are ' 8694D ' AND '8944' , stamped in centre next to the size . 76.44 mm .

also what is the best cylinder to piston clearance on this type of piston on these pro x cylinders , i have read its not as tight as stock i had thought . ?

thanks , in advance guys

[lee37vernon]

pics

[lee37vernon]

pic

[lee37vernon]

side

[christophere251]

its prob a pro x they are cast usually ithink.

[C-LEIGH RACING]

Lee, from the looks of the pic thats a Wiseco piston. The numbers on top like like a Wiseco as well.
Pro-x did have a cast piston a few years back, but had problems with them cracking.
Those pistons had a black moly coating on the outside below the ring grooves, so thats how you could tell if it was a cast.
That piston you have, it come in a white box.
I beleave your right on the hole on the intake side, it should be a square oval shape.
Piston to cylinder should be 0.0003
Neil

[lee37vernon]

i thought wiseco only made forged pistons ? also that clearance . where you taking that from . i have this in the cylinder and it is real tight looking around the skirt , i did write the measurements down but not to hand , varied top to bottom . i know pistons are bigger one end than other .???


edit .. no white box , came slid in the cylinder .

[C-LEIGH RACING]

Yes, Wisecos are forged.
From the looks of the pics, that piston looks just like a Wiseco piston for the Pro-x cylinders, except for the intake window.
The machineing around the wrist pin hole, & how the skirts are cut is just like one.
Look at the piston real close, if its been machined on the inside on the exhaust side & the intake side it for sure is a Wiseco, a cast normally wont be machined any on the inside.

Measure it from exhaust to intake side just below the intake window.
When you measure the cylinder, measure it from top to bottom, could be the bores not straight.
Neil

[lee37vernon]

thanks neil , i'll have another measure up in that spot tomorrow .

that piston is definately cast , theres no machining inside and you can see the casting swirls and stuff in the alloy inside .

my 265 piston was a cast pro x so i'm guessing this prob is too . i cant get a cross reference off of their site though , only lists by make and model . no matter really anyhow i suppose .

[C-LEIGH RACING]

It is very possible that piston could be a cast piston for a jet ski watercraft.

I would have to say, its the first cast piston I've ever seen with as much machining on the outside as that one has & the numbers stamped into the crown in two different spots just like a Wiseco brand.
Neil

[707trx250r]

That piston looks identical to my wiesco for my ct 350.
I am pretty sure it is a wiesco.
Later
Adam

[lee37vernon]

heres a pic of the inside , it looks cast to me , although it is very smooth . it has no inside machining .

[C-LEIGH RACING]

I dont know Lee, I'm still thinking its a forged Wiseco.
See the bulged out area inside on the intake side, thats normally machined out smooth from the lip of the skirt up almost to the underside of the crown.
In the close up pic, the grain of the aluminum looks like a cast piston but those walls are mighty thin.
Wonder if it could be a copy from Japan or China, its not impossable.
Neil

[lee37vernon]

not sure i'm wanting to use this piston anymore , lol .

it's weighing a tad under 7 oz , 200 grams .what would forged likely be ? this is without wrist pin .
that skirt at bottom edge ( exh side is slightly thicker ) is about 2.7mm . 13/128's inch . does that sound excessively thin ?

[lee37vernon]

what are these pistons for the big bores actually listed under , i presume they are for a std machine some where and not just for pro x .?

[lee37vernon]

someone must know this ? :confused:

[rebelbanshee]

Originally posted by C-LEIGH RACING
Lee, from the looks of the pic thats a Wiseco piston. The numbers on top like like a Wiseco as well.
Pro-x did have a cast piston a few years back, but had problems with them cracking.
Those pistons had a black moly coating on the outside below the ring grooves, so thats how you could tell if it was a cast.
That piston you have, it come in a white box.
I beleave your right on the hole on the intake side, it should be a square oval shape.
Piston to cylinder should be 0.0003
Neil

3 tenths clearance?! is that a typo? that seems alittle tight, but i dont build engines.

[C-LEIGH RACING]

Yes it is a typo :D :D :D I just caught that, it should be 0.0030


Lee,
The listing for those big bore Pro-x cylinders are in the LA Sleeve/Pro-x catolog under TRX250R.
You wont find a listing for them in a Wiseco catolog because they are custom made for Pro-x.
You might can find the big bore catolog on the LA Sleeve website listing those TRX250R top end kits.

http://www.lasleeve.com
Neil

[lee37vernon]

i did wonder , i can't even convert that down to metric on a readable scale ,lol .. .06 mm is much easier to read !

if wiseco make that for la seleeve then this is for sure a pro x . they list a cast piston . part number px , gives game away . obviously its made to mtheir spec so looks just like the wiseco ..

[lee37vernon]

i mic'd this up and there was like 15 thou at best . took it to my machinist who confirmed it and is honing it now . he reckons that piston is a wiseco forged . guess i need to look at a few more forged undersides :ermm:.
still cant see how you could 'stamp' that out , the area around the inlet side bulge .. it does have an ' eggshell' like finish though and the more i look at what some of these companies can forge i think your initial observations must be correct .

[C-LEIGH RACING]

Yes, there is a PX Pro-x number listing for big bore pistons, but they are the same as the Wiseco & the only difference is the box itself.
Over the years I have ordered each one of those part numbers & each time the pistons were the same Wiseco.
Now, Pro-x did a few years ago have a cast piston for the big bores but they just wouldnt hold up were easy to crack & come apart.
Those cast pistons looked almost like the Wisecos & were just about as thin, guess that could have been the reason for them busting.
If you see a add with pics of the big bore cylinder kits they offer, it will show that cast piston in those pics, has black teflon coating on the sides.
Was a good looking piston, I would have to give them that much credit.
Neil