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Hi guys I am installing a stock compression and bore CP Carrillo piston in my 2013 CRF 450R.. The box has a spec sheet with piston specs and a separate installation sheet which tells you how to calculate the ring gaps and according to the sheet the ring gap should be .017" using 3.78 x .0045"=.017" and Honda spec is .010"-.012" which currently is what the gap is on the CP ring in my new cylinder so I'm wanting to use the Honda gap spec. And they don't provide a install directional mark for the piston. I am using the deeper valve relief to the intake side as my direction... What's your thoughts on these two issues?

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Hi guys I am installing a stock compression and bore CP Carrillo piston in my 2013 CRF 450R.. The box has a spec sheet with piston specs and a separate installation sheet which tells you how to calculate the ring gaps and according to the sheet the ring gap should be .017" using 3.78 x .0045"=.017" and Honda spec is .010"-.012" which currently is what the gap is on the CP ring in my new cylinder so I'm wanting to use the Honda gap spec. And they don't provide a install directional mark for the piston. I am using the deeper valve relief to the intake side as my direction... What's your thoughts on these two issues?

 

okay,

well,

so.....

the side with larger diameter valve pockets is the intake side.

 

second,

their ring gap formulas are for iorn cylinders,

see our aluminum cylinders grow quite a bit

so your probably fine at 0.012"

but, 

running 0.017" is also fine, and in some ways safer if you ever got it really hot....

mine is 0.017"

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I agree with EnglertRacing. Go with the CP specs. That is the spec they engineered for their piston

 

I have run CP pistons in 2 of my 450's and my current bike is at 0.017" and the 450 I sold not to long ago was 0.017" as well.

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So I called CP tech line today.. Tech says that that .017" is definitely the ring gap to use and that they don't mark the piston for install direction but confirmed the relief with the greatest depth is the intake side.. Note that the diameters are the same but the depths are different.

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