I'd say SPI. IMO it's best quality for your $.

 

For a stock rebuild, stay away from wiseco. OEM pistons are good quality but WAY overpriced. SPI pistons are good quality pistons for a good price. IMO they are just as good as oem, but I only say that cause Ive never had either one (oem or spi) fail on me. Ive melted both, but never had one actually fail on its own.

 

For a stock rebuild, stay away from wiseco. OEM pistons are good quality but WAY overpriced. SPI pistons are good quality pistons for a good price. IMO they are just as good as oem, but I only say that cause Ive never had either one (oem or spi) fail on me. Ive melted both, but never had one actually fail on its own.

+1 Take his advice.

 

Go with spi's! Great piston for the $

 

Correct me if I am wrong but aren't wisecos main problem that they expand and contract a lot during the whole firing process due to poorer metals?

 

not poor metels. The are usually forged not cast as oem pistons. They are fine to run but the average rider just doesn't need them.

My vote is for spi's. Great piston for the $$.

 

SPI's work great. Wiseco's need more clearance to cylinder wall because of more expansion. The average rider doesn't have patience to allow the engines to fully warm up evenly and take off and squeek the wiseco's.

 

I tried wiseco before, their rings wear out quick. I have always used SPI since and never had a problem. not to mention they have teflon coated skirts and ceramic domes. great piston

 

Wiseco's are better for racers, and high HP sleds. (IE: turbo, blown, etc..)

SPI are better for the average pull-n-play rider..

 

wiseco's are forged and expand when put into stock cylinders and usually end up locking the motor up... i have heard of this happenign many many times, i would go with spi for sure!

 

I've run SPI and Wiesco. Noticed fast compression drops when I used the Wiescos, never had good luck with them either ( have bought multiple t-cats with them and had melted pistons when I got them ). Figure they make a more expensive piston ( which is nice if you have the patience for your sled to warm up ), but why spend the extra cash when you could have a piston thats practically just as nice for less than half the cost?

 

SPI's work great. Wiseco's need more clearance to cylinder wall because of more expansion. The average rider doesn't have patience to allow the engines to fully warm up evenly and take off and squeek the wiseco's.

true.

I do warm up completely before each ride, but I still won't run the Weiscos.
Being forged, they expand and contract more, and that, to me, brings on 2 issues.
1, they are more prone to piston slap when cold (before/during warm up)
2, since they expand more, it stands to reason they they will expand more if I get a little hot.

I just think that cast pistons are better for longevity.

The one reason I can see for running Weiscos is for competition.
A lighter weight, matched weight set of slugs will take less energy to move through the stroke, and thus, put that little more out. MUCH more maintenence in racing than in riding though.

 

I'd like to clear up an appearent misconception. A forged piston does not expand more than a cast piston because it is a forging. It is not the METHOD of manufacture that determines how much a piston will expand. It is the ALLOY that determines that.

 

While we're clearing up misconceptions about pistons...

Forged pistons are considerably stronger than cast pistons.

Cast products, the metal molten metal is simply poured into a mold, cooled, removed from the mold, then the areas that require it are machined.

Forged products, the metal is poured into sheets, and when partially cooled (still red hot) it is stamped into the whatever shape then allowed to cool the rest of the way, then machined. This aligns the molecules as the metal is stretched into the correct shape, making forged products considerably stronger.

 

Forged pistons are made out of several different types of materials. Now I don't know a whole lot about the different materials out there (as there seems to be a lot), but what I do know is that what the forged piston is made out of changes how it reacts to heat, and how strong it is. Some materials, such as 4032 alloy, is said not to expand as much as others. Also, the higher the silicone content in the piston, the less it expands to heat, while sacrificing some strength.

 

go with spi they worked awsome in ma sled

 

^^ Agreed..

 

No matter what piston you buy, your machanic/machinist should have both pistons and cylinders in hand before doing any work. That way you are not getting a generic bore size. Every cylinder should be machined to the correct clearance for the piston going into that hole.

The quality of the pistons at a reputable aftermarket pistom maker should be on parr with an OEM piston but at a good cost savings. Some people are only concerned with the bottom line-how much will this cost me. Others will go the money is no matter route and buy what they percieve to be the best. Any piston mentioned here will work provided they are fit correctly and the rider understands the thermal expansion characteristics of the chosen piston.