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Discussion Starter · #1 ·
Ok purchased a non running complete 2001 polaris sportsman 400 for a father/son project.. rebuilt carb cleaned tank...no start..ran compression test of 70psi... ok fast foward..tore down cylinder walls good rings worn out.... now I can not find 87mm rings... technically this 400cc is a 425cc according to measurements... searched high and low for 400cc top end kits and can only find 500cc kits but thats a 92mm..can I just bore my jug out to a 92mm and use a 500cc kit.... please help so we can go riding before winter hits!!!!
 

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Yes, you can.
A wiseco piston kit, if you can find it.
 

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Discussion Starter · #3 ·
Yes, you can.
A wiseco piston kit, if you can find it.
Not answering my question....I know of wiseco piston kits....but cant fint any in a 87mm bore just 92mm which is a 500cc kit.. what are other sportsman 400 riders using when doing top end rebuilds???
 

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I just answered your other post. If you only want rings and gaskets you'll have to go to Babbits or Cycle parts warehouse or somewhere similar to order standard rings and gaskets individually. Your "400" is actually a 425. I doubt you'll find a "kit". For the money you'll spend on individual parts, I'd probably just go with the Namura piston kit.
Good luck and let us know how it goes.
 

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Discussion Starter · #5 ·
yea after doing some searching i found the 87.9mm std bore piston/rings for 89.00 and a complete gasket kit for A 400/425 MAGNUM/SPORTSMAN for 44.00 shipped so im gonna take this route.. hopefully once installed i can get this mofo started.. had gas and getting spark after a fresh carb rebuild.. hopefully this low compression was my problem... I myself and my son are ready to go riding.......
 
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