MaineSled

While SPI & Standard or coated pistons are fine...you'll be hard pressed to beat a set of Wiesco if you properly warm up your motor till the heat exchangers are warm like your supposed to.

***Another reason why I choose Wiesco is I been using them for over 30 years and am comfortable with a "known" product but in all fairness materials & coatings have come a long ways over the years so I'm sure the newer stuff has come a long way and are most likely comparable.

indyryder500

yeah Wiesco has come a long way in the last few years also.

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97 ultra spx slp can geared clutch and 144 studs.(mine)
96 XLT studded with reverse(12y/o son)
98 xcf 440 (wifes sled)
96 puma 340 elec start(kids sled)
96 cougar 550 2up bone stock (sold)
96 XCR 440 clutched (sold)
92 indy 500 bored,clutched. piped(sold)
85 indy 400 (11 y/o son's sled)(sold)
87 yamaha excel 340 (parting out)(sold)


2011/2012 miles :00000000

aduck

every motor i open up gets wisecos. like said before as long as you let em get to operating temp youll have no issues which you should do either way.

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93 mach1 670
02 rmk 800 162
95 powder special 580

musicfreako

Oh I like weisco's. I put them in my Camaro, quad and lawn mower. But in a Snowmobile, they're too temperamental. I always let my stuff warm up, but there's too many variables in snowmobiling.

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The only cat I'll ever own will have a track and not require a litter box

Current rides

98 ZR600 EFI (03 zr900 skid, reverse, fox shocks, clutched)
97 Polaris Indy 500 (stock)
91 El tigre EXT 530 (01 Zr skid, clutched, MINT)
94 Polaris Indy trail deluxe (very heavy!)

New rides
90 El tiger EXT 530
98 Zr 600 Carb
00 Zr 600 EFI (trophy winner in the 700 class drag races)

aduck

ive never had any issues to date with em.

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93 mach1 670
02 rmk 800 162
95 powder special 580

Skid

Used Weisco on a couple of my bikes and was happy with the gains but in a 2 stroke snowmobile the stock pistons or SPI work great and are not as particular as the Weisco.

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94 Polaris XLT - XTRA 10, Ski Skins, 3" riser
97 Polaris Ultra
96 Ski Doo Formula III 600 (sold)
97 Polaris XLT Limited - XTRA 12 (My Son's)
80 Kawasaki Intruder (sold)
72 Polaris 340 Colt SS (sold)

racing_kidd

Hello im still fretting on this one, two years ago I purchased 3 SPI moly coated piston kit off of e-bay, the rebuild occurred on a 1998 Polaris Ultra at 3000 miles and its been 400 miles since and the rings havent even seated yet, the compression still sits at 110 psi across the board, the cylinders were not glazed on inspection, Im wondering if thats what is happening, atleast I wasn't concerned about the quality of the SPI piston being purchased from e-bay at the time, could they have been misfits? The likely hood of being the only one having this issue is likely low I dont want to incriminate but I might have to call up the shop that sold me the pistons, as the mechanic who rebuilt states SPI is as reputeable as he is LOL, hes my Uncle so I could never fault his expert way. Where would you buy your engine parts?

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racing_kidd

Old Man

@racing kidd - Are you doing your compression test with all the plugs out, throttle held wide open and pulling it over at least 5 to 6 times or cranking it until the needle stops moving? Have you tried using a different compression tester? Just a couple of thoughts before assuming the worst.

rcslsafut

i totally agree !!!