Take a look at this Wiseco piston guys

[BULLET99Z28]

I got the piston and cylinder work done on my CT310, 2nd bore(72.25). I ordered a new head/dome, piston kit and gasket kit from ESR. Notice it has 9 drilled areas on the exhaust side, vs the 3 drilled holes on my Wossner. The owner of the performance shop where I had the cylinder honed said that he hadn't seen them like that.

Should I send that piston back and get another Wossner? Ive been outta the 2stroke game for a long tie, wiseco's were all we used to use. But I know that both brands are good. The box is labeled- esr ATC 250r 85/86, looks to be the wiseco label. Piston is correct and cylinder has been honed to match.

He said if I want, just drill the 3 center holes. What do you guys think? I want to put her back together asap and get some seat time!

http://i182.photobucket.com/albums/x237/BULLET99Z28/2012-04-23144632.jpg

Here's the Wossner that came out of it(only has the 3 holes on the exhaust side). Only had about an hr of runtime, blew a hose and got a little to warm for my liking, so I just ordered a new piston and had the cylinder honed to match. Is there any advantage to the differences on the intake side?
http://i182.photobucket.com/albums/x237/BULLET99Z28/2012-04-23144850.jpg

[Honda 250r 001]

Im guessing those would be holes to help lubricate the exhaust bridge between the main exhaust port and the smaller exhaust port on the sides.

[BULLET99Z28]

Thats just what I was thinking, for lubrication. I was wondering what is a better set-up. Do you think those little recessed areas would hold that much oil, or should I drill just the center row all the way through?

[Honda 250r 001]

I think if it were me. I would just drill out the top two center holes and call it good. Im no expert though. But I just dont see the secondary exhaust port bridges expanding enough to need extra oil there.

[89trx250r]

Go on the other site and ask Carlos or Neil. There is no need to sit here and ask a bunch of people who are just going to give you there opinion when you can go there and get the facts...

[trx250r 88]

do you have a exhaust bridge on your cyl.? i think ct,esr use the 85-86 type piston with open exhaust port.those marks on the piston are there as starter holes to be drilled out only if you have an exhaust bridge type sleeve.

[BULLET99Z28]

Originally posted by trx250r 88
do you have a exhaust bridge on your cyl.? i think ct,esr use the 85-86 type piston with open exhaust port.those marks on the piston are there as starter holes to be drilled out only if you have an exhaust bridge type sleeve.

Yes, my sleeve has an exhaust bridge, and the shop relieved it slightly whe they did the bore work. I believe its an original sleeve, and I think Neil had dome some work on it, Bought top end from a board member. I will give one of those 2 a shout and see what they recomend

[machwon]

Those starter holes are a very nice upgrade on the new pistons. It saves time to mark the right spots and helps you avoid out of control drill bits. You can drill out the ones you want. If you have the bridge I would use all 9, if you don't have the bridge then use the outer 6 and leave the middle ones alone.

[Ruf Racing]

They were designed to hold oil for lubrication. Not to be drilled. If you have the bridge port, you could drill the center three only.

[Langbolt]

I'm wondering if the auxillary ones are there to help with cooling when the cylinder is hotter in the exhaust area....

Machwon,

I saw your post on machining material out of the coolant passage to help cool the exhaust area.....maybe this is also why they added them.

:D

[C-LEIGH RACING]

Bullet,
If you've not installed that piston yet, if you would, put up another pic of the side of that piston around the wrist pin area so everybody can see the changes.

By you having the bridged exhaust port, I would at least drill out the top two holes in the middle & maybe if you wanted to, one on each side just to add a small amount of cooling lube to the sleeve between the main & aux exhaust ports.

I sometimes after drilling out the holes, will take a bit larger drill bit & do a lite counter sink on each hole just so it will hold a bit of cooling oil, but to each their own on what they do.

That looks to be one of the new machined pistons ESR is offering, with the different machining on the sides around the wrist pin, that will to some extent stop the port linking issues on the Pro-x & ESR cylinders.
Those pistons, also have the wrist pin hole machined more to the exhaust side, off center, to promote a better power stroke.
Neil

[BULLET99Z28]

No problem Neil, haven't installed anything yet. According to ESR website, the description of the piston says that the wristpin location has been moved forward. Side pic.

http://i182.photobucket.com/albums/x237/BULLET99Z28/2012-04-24134032.jpg

Label on box

http://i182.photobucket.com/albums/x237/BULLET99Z28/2012-04-24134122.jpg

Side shot of old wossner
http://i182.photobucket.com/albums/x237/BULLET99Z28/2012-04-24134153.jpg

[C-LEIGH RACING]

Yep, that is one of the new ones.

Just as a test like, take that Wossnor, site it straight down from the top & draw a line on the crown direct in line with the front machining edge around the wrist pin & then stick the piston back in the cylinder & see how close those lines are to the edge of the aux exhaust ports.

Afterwards, if you would & I know this is asking a lot, put up some pics of that test to show how close everything is machined.

I have an old sleeve that has been taken out of a cylinder & an old piston cut in half that would really show what is happening during port linking, but cant post a pic.
Thanks, Neil

[machwon]

The pistons are a big improvement over the old ones. They are much lighter than some of the stuff and the intake boost hole is larger too. They used to pre-drill the center holes, which made some of us engine builders cringe. Especially when we would want to remove the exhuast bridges on the bigger cylinders. The new ESR cylinders don't have an exhaust bridge so the pre-drilling was stopped. The only part I don't like is how they angle the bottom of the exhuast side of the piston up. You have to be really careful to not expose the exhuast port on TDC when doing a stroker motor.

[BULLET99Z28]

Heres some pics for you Neil, hope its what your looking for. Its no biggie, i do quality control, so it was a snap.

http://i182.photobucket.com/albums/x237/BULLET99Z28/2012-04-24181419.jpg

http://i182.photobucket.com/albums/x237/BULLET99Z28/2012-04-24181438.jpg

Aux exhaust ports
http://i182.photobucket.com/albums/x237/BULLET99Z28/2012-04-24181556.jpg

Wossner in bore, line is front of machined edge of piston as in pic above
http://i182.photobucket.com/albums/x237/BULLET99Z28/2012-04-24181945.jpg

New Wiseco, front of machined area, and front of wristpin area
http://i182.photobucket.com/albums/x237/BULLET99Z28/2012-04-24182005.jpg

Wiseco in the bore
http://i182.photobucket.com/albums/x237/BULLET99Z28/2012-04-24182111.jpg

Let me know what you think. Next I will post the 2 side row of dimples on the piston in relation the edges of the main exhaust ports

[C-LEIGH RACING]

That is perfect, just what I was looking for.

Now, you see on the Wossnor piston how much of the machined area around the wrist pin is open to the aux exhaust port, which in turn, as the piston is traveling up or down it is linking the main transfer ports on both side to the aux exhaust port.

In turn, on the downward stroke, fresh charge is being blown out into the exhaust around the machining on the piston & then on the upward stroke, if the pipe is working right, spent exhaust as well as some unburnt fresh charge is being blown back down into the port.
Makes for a very confused engine when it comes to the fresh charge flow up threw the ports.

As you can see with the new type Wiseco piston, the machining around the wrist pin, is far away from matching up those ports together.
Thanks Bullet.
Neil

[BULLET99Z28]

Let me pick your brain on this Neil, here I marked the 2 side rows of dimples on the exhaust side and marked the edges of the ports. They look a lil to close. I don't want to lose compression or charge. What do you think I should do with the 6 outer holes, and should I drill all 3 center holes, and what size hole? Thanks for all your help. Hope it was a help to the board.

http://i182.photobucket.com/albums/x237/BULLET99Z28/2012-04-24183453.jpg


The 2 small marks at app. 10:30 and 1:30 are the centers of the outer rows of dimples. Either way, I figure they should hold some lubrication and help with temps on that side of the cylinder.
http://i182.photobucket.com/albums/x237/BULLET99Z28/2012-04-24183652.jpg

[Langbolt]

So I guess it'll just be a matter of time before Wossner & L.A. Piston get on track and change them to the NEW standard like Wiseco did.....But I wonder what they're gonna do with all the old ones ? Sell them to the people that don't SPECIFICALLY request the NEW DESIGN...

I snagged a pic of the 330 Piston from L.A. Piston....and when I saved it.....the file name defaulted to Wossner-2-str

:devil:

[C-LEIGH RACING]

Nate,
Probably be the best, to use at least two if not all three of the center holes in the piston, to cool & lube that bridge in the main exhaust ports.

As for the outside cooling holes, according to those markings, how the indents are lining up with the outer bridge, I wouldnt drill the hole or holes where the indents are located on the piston.
Those cooling holes, need to be in the center of that bridge, between the main & aux exhaust ports to be of any good.
If drilled where the indents are already located on the piston, all the cooling & lubing flow will be blown out into the main exhaust port & will do no good.

No more area as there is to cool, between the main & aux exhaust, one hole on each side should be enough, but, there has been many of those cylinders in the past, didnt have a cooling hole in that area & never was a heat related problem seen.

Before you get ready to put it back together tonight, be sure those ports are champhered good, because they dont look like much has been done to them.
Dont what to end up snagging a ring on a fresh piston from ports not champhered enough.

Langbolt,

That could be a new 330 piston, but I dont understand the single ring idea.
Honestly, it looks more like a CR250, KTM or KX 200 piston than one for a big bore TRX engine.

I dont know if it was on here or over on trx 250r .net, Carlos mentioned LA was just before re-designing their 250R Wossnor pistons.
Neil