pro x pistons?

[fred-o]

are they good?

[dajogejr]

Why not start a single thread about pistons instead of a different thread about each and every type.

Honestly...I know the forged pistons are roughly the same in price.

I wouldn't put a cast piston back in the bike if you forced me to.

 

How much money are you going to save with cheaper pistons?

[jayzx10r]

IDK what the quality of Pro x pistons is but when we dropped off my friend's cylinder to get bored to his new Pro-x, pro-x has their own spec for boring their cast pistons that is substantially different from stock cast boring sizing. If I recall, the tolerance needed to be larger than stock.

The visual led me to believe they were a good quality piston but really, why would anyone choose a cast piston over forged??

[banshee67]

my stepmother has had the same .80 over bored pro x piston ( new rings for every now and then too be safe) for several years. just a few months ago we took her bike apart to check cylinder walls and pistons and everything checked out we honed out the cylinder and put it back. they boring specs really are.... different. from the other brands. kinda a pain in the ass. but decent piston when taken care of

[CTxBanshee]

If I were you I would just drop the extra cash on quality. I've heard bad stuff about pro-x. The weisco is worth it for sure.

[T_Shee]

if you wanna save some money you can get wsm platinum series forged pistons on ebay for around 100 a set. i had some and i was really impressed with how beefy the rings are.

[bad 350 shee]

wiseco is the only brand i run!

[Yaxy]

Most on this web site will recommend Wiseco because they are cheaper, lighter and a forged piston is typically stronger than a cast piston. When going to a forged piston you will need to run a larger piston to cylinder wall clearance than you would need to run if you ran a cast piston such as Pro-X. The extra cylinder wall clearance necessary for a forged piston typically results in more piston slap and wear on your cylinders and will result in more frequent engine rebuilds. WIth this in mind you need to weigh the benefits and risks of each.

 

In terms of piston strength If your jetting is correct you will not have a problem with either. If you jetting is off it won't matter what piston you are running the result will end the same.

 

 

Yaxy

[AWR]

more clearance is needed because a forged piston expands more than a cast piston as it reachs operating temp....more frequent rebuilds?WTF..just for fun take an old cast piston and an old forged piston and lay them on the garage floor and start pounding the fuck outta them with a hammer.you will be amazed at how much tougher a forged piston is.

[Vintage Smoke]

more clearance is needed because a forged piston expands more than a cast piston as it reachs operating temp....more frequent rebuilds?WTF..just for fun take an old cast piston and an old forged piston and lay them on the garage floor and start pounding the fuck outta them with a hammer.you will be amazed at how much tougher a forged piston is.

 

You are right about bashing the two with a hammer, but put the two, one on top of the other, in a hydraulic press. Now crank down the press slowly and the cast piston will squish the forged.

 

So which one is actually stronger?

 

A while back I had a long conversation with an aquaintance who actually designed motorcycle pistons for Keith Black. If you never heard of them...google it. I'll pass on what I learned from him.

I will say that each one has it's benefits. The info I will list below is a GENERAL comparison of cast and forged pistons. Some of the points are important to the Banshee engine and some might be important to other applications.

 

Manufacturing:

A CAST piston is made by pouring molten aluminum into a mold. Once molded (or cast) a minimal amount of machine work is needed to create the finished product. Since the aluminum is molten or melted it is free to flow in and around all the pockets and spaces in the mold. This creates a piston with a minimal amount of excess material.

A FORGED piston is made by heating a slug or lump of aluminum CLOSE to it's melting temperature to soften the aluminum and then forging (pressing or hammering) it into a die that approximates the shape of the piston. This is a ROUGH description of the forging process. If you want to know more google that too..LOL. It is then machined to final shape. A forged piston is unable to attain the complex shapes that a cast piston can (without expensive machine work) since the aluminum is not fully melted. If you look at the underside or inside of a piston, and the space between the wrist pin boss and crown is solid, it is most likely forged. If there is space between the two it is most likely cast. This is why you see those "mystery holes" machined into the sides of many forged pistons. This is to remove excess material bringing the weight of the piston closer to stock without having to do expensive machine work on the INSIDE of the piston.

 

Materials:

Cast - The material in a cast piston is lighter than forged which means the weight of the piston will be closer to OEM. It is less dense than forged meaning it will expand less as it heats up which allows tighter piston to cylinder clearance. It is also harder which means it will last longer in regards to wear. Being harder also means it is more prone to shattering when subjected to preignition or detonation.

Forged - The material in a forged piston is denser than cast which means it weighs more than cast. It will also expand more when it heats up necessitating a looser piston to cylinder clearance. It is softer than cast which means it will wear faster than cast, but also means that it will deform slightly (rather than shattering) when exposed to detonation, preignition, or used in turbo or nitrous applications (which are more prone to preignition and detonation)

 

Also....

A cast piston:

- is able to run at a tighter piston to cylinder wall clearance. This may allow for: quicker warm up, the potential to to provide better sealing, the potential to better transfer heat from the piston to the cylinder, and less rock in in the bore which can extend piston and cylinder life.

- is lighter than a forged piston which can affect balance as well as higher RPM loading on the reciprocating assembly as a whole (crank, rods, crank bearings, rod bearings, etc)

 

To be continued.......

[Vintage Smoke]

Continued.......

 

So...which one is better? Well it all depends on your application. I frequent this board as well as some of the 2 stroke street bike boards. Particularly the RD350/400 boards. Those bikes use an engine which is VERY similar to the Banshee engine. The banshee engine pretty much evolved from the old RD engines. There are a couple of very important differances though. The operating temp of the RD engine is much less stable than the Banshee engine since it is an air cooled engine. The RD's typically see many more hours on them since they are street driven and rack up the miles. I know you guys run your banshees hard, but not too many of you can say you have 10,000 miles on a banshee. I am NOT knocking anyone, I am just pointing out differances.

 

It's really funny to see the different attitude between the people on the different boards. A bunch of the guys on the street boards really rip apart the Wiseco pistons. They regularly call them Seizeco. A bunch of people here call the ProX pistons "Junk cast pistons". Yet...the Wisecos are pretty much the accepted replacement piston here and the ProX are the accepted replacement there!!

 

In regards to a Banshee, a forged piston such as a Wiseco will last plenty long since it is common to tear into the engines for various reasons when they have much less hours on them than a street driven bike. Banshee engines also run at a much safer and more consistant temperature lessening the chance of seizure when compared to an air cooled engine. On the street bikes most of the guys appreciate the longer life that a cast piston gives. It is also critical to be very careful with timing on those bikes as well. Installing something like a "+4 degree timing plate" is absolutely un heard of!! Timing is set using a dial indicator in the spark plug hole to precisely set timing. A differance of 4 degrees could easily mean the differance between a strong running motor and a melt down. (there is also the fact that most of the RD's still run a static points type ignition). The Wiseco pistons just plain put up with more abuse in a Banshee engine than the average cast piston will...but it does not last as long in the air cooled street bikes (anyone see where I am headed with all of this)

 

So what's my point? Easy...one is not necessarily better than the other.....you just need to pick the right part for your application. When in doubt ask a pro with the experience needed to point you in the right direction!! One more good reason to support the site sponsors!!!

 

I posted this here hoping that some of you might find this useful or at least interesting reading.....or it may just be well past my bed time and i am babbling like an idiot!!

[apeik]

Good points, and an interesting read vintage. Always nice to learn new stuff and different point's of view.