wiesco vs. pro-x vs. WSM vs. OEM

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#1
we need a good piston discussion over here, so.........

seems as though most peeps are running pro-x, but lots running wiesco's as well.....

getting ready to build my new magoo motor and have to make a decision here pretty soon...now, Ill probably just put in whatever paul tells me to run, but whats been happening lately on the piston scene?????








:sneaky:
 
Joined
Jan 16, 2006
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#2
pro x and oem are my choices. they are cast and very reliable

wisecos are forged and you have to be careful with running them cold. however, they make the flat top pistons. (i believe you can use KAWI pistons in a flat top situation though)

wsm, like sbt, is trash.
 

Matt_E

steals hub caps from cars
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#6
I am going to put Sudco 83mm pistons in my engine in a couple of weeks. The look identical to Pro-X.
 
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#7
pro x this time round
used old wiseco once in a 750 sx and ran hard and strong for for years with no trouble ( just have to be very spot on with the clearance piston to wall, they are not forgiving i am told)
 

Mile9c1

X-H2O.com
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#8
Sudcoo are OEM equivalent, so are ART pistons. One of the nice things about cast is since they use a smaller bore, if you mess your engine up you might be able to get away with a hone and same size Weisco pistons. Just my opinion.
 
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Sarnia Ontario Canada
#10
Here's what I've heard.

Round tops.
Pro-X and OEM are very similar in quality and construction and seem to last well.
Wiseco weigh less which should give better throttle response but don't last as long as Pro-x or Oem before needing a re-ring or rebuild. Also with Wiseco you do need to be a little more careful with warm up and initial piston to wall clearance since they expand more or quicker than Oem pistons. Good pistons for people who don't mind doing a little more maintance.

Flat Tops vs Domed Pistons
Flat tops are not truely flat they just have a flatter dome.
An example of a flat top piston is a Kaw 750 piston. Yamaha 701's are domed.
The flat top pistons make a little more power. I've heard aprox 1.5 hp per side.
In the old days you would install Kaw 750sx type pistons in the Yamaha 701 motor to make a flat top motor. Wait it is not that simple. The piston ring ends lined up with the transfer ports instead of inbetween the ports and I believe the pistons were just slightly too tall requiring you to grind the squirt. Also the wrist pins height to the top to the piston is not the same from the Kaw to Yam pistons. To make this motor you also had to recut the cylinder head and possible deck or mill the cylinder.
I believe you can now buy aftermarket flat top pistons made special for the Yamaha motors but I'm not 100% sure what kind of motor modifications are required. Ask Paul/JrMagoos about this one.

Later
Steve

Please correct me if I've made any mistakes.
 

Mouthfulloflake

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#12
Here are some pics comparing pro-x to Wiseco
these are Kaw 750 pistons, but you can get an idea of the differences in a cast vs forged piston from these.

Wiseco on the left, pro-x on the right.

notice the extra bosses in teh wiseco wherethe pins to locate the rings go in.
beefier around the piston pin also.
 

Attachments

SUPERJET-113

GASKETS FOR CHAMP BRAP!
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#14
I've always used Wiseco's with no problems whatsoever. As menttioned as long as they are set up right, and you warm your boat up on the trailer, then in the water a bit, no problems.

Dont think this has been metioned about pistons..
If a skirt breaks on a cast, it crumbles into many pieces and can trash a whole motor whereas a forged piston is a stronger and lighter piston and if it does break it will only be 1 piece or so and wont crumble and will hopefully fall to the bottom of the motor and not do a bunch of damage that a cast piston breaking would do. Thats another reason why racers like the Wiseco's.
I have no problem using Pro-X or OEM, Art, Sudco either. Still leary about WSM, even though I hear the "Platinum Series" is suppose to be decent according to a buddy of mine that has a rental business and rebuilds all his own cranks with WSM kits. I still wouldnt use WSM just because of a bad experience I had a long time ago trying to use one of there piston kits in a ski i was going to sell. The rings lasted like 3 hours of riding before their tension gave out and I slowly lost compression. I thought the rings look EXTRA cheesy to begin with... Anything but WSM IMO..
 
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#16
wisecos! they are lighter and stronger than the cast pistons. stay away from wsm and sbt as they are junk. pro-x or oem are your best bet for cast pistons. these days the wisecos don't expand as much as the wisecos from yesteryear because of a newer blend of material and manufacturing now used. when all is said and done you need to pay extra attention to who bores your cylinder, this is where most problems originate. believe it or not a LOT of people don't know how to bore a cylinder right, sad but true. make sure they are straight, round and to spec. and ALWAYS check your squish!
 

waxhead

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#17
if a large bit falls to the bottom of the engine then the crank will pick it up and smash it every where anyway
so i dont see the issue about how they break up as being that helpful
i have used wisecos i prefer to use cast now
i was having issues with skirts collapsing and this was on a torque plated cylinder

wiseco gave me my money back on 12 pistons so even they acknowlodeged a problem
however this was a year ago so they may have changed since then
 

waxhead

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#19
torque plated cylinder
you bolt the manifolds on the cylinder
you machine the centre out of an old head and the centre out of an old set of cases
that way when you bore the cylinder is already pulled the same as if it was torqued up as in the same when you have your engine put together
when you bolt up a cylinder you will find they pull out of round and this gets over the problem
it makes for a perfect round cylinder for your pistons to run in
 
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