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Hi guys i have a 01 yamaha raptor 660. I need to replace the valve stem seals on it so i decided while im taking everything apart ill check out the piston and piston rings. How do i tell what piston i have? I looked online at yamaha and they gave 3 piston options std, .50mm, 1.00mm. If i measure the pistion across it's 100mm. the top of the piston says 3YF and below that at the bottom it says E X. Thanks
 

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I am not sure on this... Std is stock. .50mm and 1.00mm is overbore pistons. If you bought the quad new and have never rebuilt it, it would be a std. size........ I think. I wouldnt go through Yamaha. I would go through Dennis Kirk or a local quad shop. I might be wrong. I guess I am not much help:lol:
 

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3YF is an OEM marking, sounds like you have a stock piston.
 

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ok thanks, does anyone know if the 100mm across is the std piston?
If you used a micrometer to measure the piston and you have an exact measure on it then yes, 100mm is stock.
I only say this just in case you used a metric ruler you could be 0.5mm off.
 

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I am not sure on this... Std is stock. .50mm and 1.00mm is overbore pistons. If you bought the quad new and have never rebuilt it, it would be a std. size........ I think. I wouldnt go through Yamaha. I would go through Dennis Kirk or a local quad shop. I might be wrong. I guess I am not much help:lol:
See I have no idea about engine stuff:lol:
 
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