my new triz wiseco piston not the same

[zzmegad]

My last 2 triz pistons have had pockets milled in them on both sides above the wrist pin. I noticed the new one I bought from DK is missing these. Im kinda bummed about this, what were these pockets for and I wonder why this one doesn't have them

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[sledcrazyinCT]

It is safe to say it helped with fuel transfer... does suck they are not what you expected

[RubberSalt]

If there is enough meat on it, you can just drill them in there if you like them. My first guess is they help with lubrication. On the bottom, is there little oil holes for the pin boss? Also, is 1 a wiseco?

[tecat-z]

Old Wiseco pro-lite pistons had this area removed during machining. Many old cast pistons were poured with this area open too. It was simply a way to lighten piston. Oem's saved on material during manufacturing, which saved money. But, in Wisecos case, this removal costs them time and money(due to machining process) So now we get heavier than necessary pistons. Has nothing to do with transfer. Many oem Tri-z pistons are now nla....which were the lightest of them all. Remember, 83-87 yz pistons are also a great substitute for the 85-86 ytz design, which may help on locating certain sizes.

[zzmegad]

ah good deal, not to bad then i guess, and yes they have all been wiseco pistons. thanks for the tip about the yz pistons. Another question: What do you guys think about this connecting rod kit? Price is right anyways...

http://cgi.ebay.com/ebaymotors/YAMAHA-YZ-250-WR-250-TRI-Z-250-CRANKSHAFT-ROD-KIT-LOOK-_W0QQcmdZViewItemQQhashZitem2a0fed5456QQitemZ18065 5838294QQptZMotorcyclesQ5fPartsQ5fAccessories

[leevarnado]

i might be wrong but it think the holes were for oiling the piston pin.wiseco recommends drilling the holes.

[Bryan Raffa]

i might be wrong but it think the holes were for oiling the piston pin.wiseco recommends drilling the holes.

you are wrong,, there for oiling a power valve or a exhaust bridge... only..

[leevarnado]

i knew they were for oiling,got that right,lol.

[tecat-z]

Wow really! Again guys.... The material is removed to reduce weight of the piston. That's it. Cast oem style pistons had the cavity cast into the "slug" as it was poured. Wiseco "pro-lite" pistons had them machined into the slug. This was considered a "performance style piston" back in the day....... Pro-lites are no longer made for tri-z's. Only leftovers. Pin is oiled from underside of piston through small holes on both sides of boss. LOOK:-) Neither the Tri-z or YZ used a split style exhaust "bridge" It has NoThInG to do with oiling anything.

[Bryan Raffa]

correct eddie... we were talkin about the exhaust port..

[sledcrazyinCT]

Check out this link to another site where I posted the same question, some interesting reading:wondering. Lots of opinions


http://vintagesleds.com/bs/index.php/topic,56792.15.html