weisco vs. oem

bolin22

bolin22

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wiseco vs. oem

the thread "when is it time for a rebuild" brought this up. what are ur comments and opinions on Wiseco vs. OEM for stock size replacements......are there really any advantages to running wiseco's over oem for a non race motor???
 
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ABSOLUTELY NOT!!!!!!!!!!!!!!!!

the stock oem pistons outlast and out perform the aftermakets by a mile, thicker rings for longevity and tighter skirt to wall clearance for increased stability and ring sealing.

the reason for aftermarket pistons working good in a race engine is the thinner rings are less drag on the cylinder, looser fitting pistons dont drag in the cylnders, some of the pistons are lighter, this is faster revving, but they have one major shortcoming life expectancy is half of stock sometimes less then that. A wiseco ring will not live half as long as a stock yamaha one!
 
my thoughts exactly......

another reason i ask this is because i was thumbing through the hauck catalog (sp)
and they offer replacement stock and oversize....advertising them as if they recommend them for replacement.......
 
As mrviper said, you will get much shorter life on average with the wisecos than with stock pistons. Aftermarkets have thinner skirts and often less support around the wrist pin, narrower rings, and proper warm up is MUCH more critical with the aftermarkets because of the large skirts clearances. Unless it is a race engine, use oem yamaha pistons.
 
to clarify: the reason that wiseco (and all forged) pistons run a wider piston clearance, is that the forged aluminum has a higher expansion rate than powder-forged (the processes sound similar, but believe me, they're not). At operating temperature, both pistons will have the same clearance (atleast in theory that's the case).

I haven't measured the difference in wall thickness between an OEM and a wiseco piston, so I can't comment on that, next time I have a wiseco one in my hand I'll mic it and post up tho. I'll get the measurement for the OEM one hopefully later this week. I'll see what I can do to find the tensile strengths of both materials, honestly it'll be tough to find it for powder forged metal tho, that process is newer than my mech. eng handbook. I'll flip thru the SAE resources and see if I can't find something.

should we sticky this?
 
Probably another post to go in the tech section FAQ? Too many good posts the last couple of days and if something isn't done they're gonna be forgotten about again.
 
change_up said:
Probably another post to go in the tech section FAQ? Too many good posts the last couple of days and if something isn't done they're gonna be forgotten about again.
Click to expand...

i agree..FAQ's
 
OEM Viper piston skirt thinkness (new) is. 2.77mm on the intake side. 1.87mm on the exhaust skirt. Measured approx 10mm from the bottom.
 
my SRV540 has has the same wiseco pistons in since 1998 and still running strong, I think they have improved sind the late 70's
 
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