Wiseco Piston Cylinder Wall Clearance

[Predator212Laxer]

Hey after a super long couple year haitus from my go kart I decided with my buddy to start the rebuild of my predator and add some new parts. So I ordered the Wiseco piston set up from AGK (affordable go karts) comes with the ARC long rod designed so the piston can be a "drop in" however, we noticed initially the piston had tons of slop side to side. I used a micrometer and measured the cylinder walls and it is perfect at 2.755. The stock piston measured around 2.748, while the wiseco measured 2.735! The part number on the piston is the correct one for the "stock predator 212cc bore" doesn't seem like it though. Any ideas? Could wiseco have messed up and machined the piston incorrectly?

 

[Mariah]

I agree somebody messed up on the diameter, .020" clearance is more than I have seen on worn out oil burners (engines)!!!

 

[SAT]

I would call Wiseco and get it right for sure.
Hope this helps,
Steve

 

[Predator212Laxer]

I agree somebody messed up on the diameter, .020" clearance is more than I have seen on worn out oil burners (engines)!!!

Yeah the bore is in great condition. Granted the engine is the original predator from 2011. Still has stock crosshatching. Gotta be the piston

 

[Predator212Laxer]

I would call Wiseco and get it right for sure.
Hope this helps,
Steve

For sure I’m going to give them a call today and see what the minimum size for that part number should be. I will try to contact AGK first


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[MB165]

yeah that's weird, like it came from the factory 20 over? is the old piston marked 20 over?

 

[Predator212Laxer]

yeah that's weird, like it came from the factory 20 over? is the old piston marked 20 over?

It’s undersize for my bore. I ordered it as a Predator 212 piston so maybe they sent the standard GX200 one


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[Predator212Laxer]

*update* I spoke with Hunter at ARC Racing in Georgia. Apparently the Wiseco Pistons have a large taper set in them from the factory to allow the aluminum to expand in the hottest area (the top.) So my piston is actually the correct one. Sort of went against my conventional thinking with engines but I have never dealt with anything other then stock pistons. Just FYI


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[ole4]

You should be measuring the piston diameter at the bottom of the skirt 90 degrees from pin hole or if you don’t have measuring tools a feeler gauge between bottom of skirt and cylinder wall by placing piston upside down. Again 90 degrees to the wrist pin.