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New piston comp ratio question.

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So I recently aquired a box of cfr450r parts that my uncle had laying around. He bought a bunch of stuff for his 02 many years ago, and then bought an 08 450r when they came out and sold the 02. He forgot about the parts box, until recently when he stumbled upon it in his garage.

In it I found a std bore 11.5:1cpr wiseco piston. Complete Wiseco gasket kit. A set of KibbleWhite SS Intake valves/springs/retainers. And a few other odds and ends.

Tonight I pulled the valve cover off my 05 450x to check valve clearance. They have tightened up a bit again, and I think this will be my last adjustment before replacement.

So, if I am going to pull the head to replace the valves, I might as well do the piston. The KW valves are 36mm. So they will be 1mm oversized compared to stock. My question is about the piston. It is 11.5:1 and from the reading I have done, stock is 12:1. Will I even notice a difference?

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Okay. Time for the cyl head to come off.

So I have the kibble white ss intake valve kit, PN 0926-0443 for for 02-07 crf450, 36mm valve. Probably going to order oem exhauat valves. I have a machine shop local for the work.

Figure I better do the piston too. So stock Comp ratio is 12.0:1. My piston kit, Wiseco PN 4653M09600, says crf450 r/x 11.5:1 comp ratio.

I am still confused on whether or not it'll really affect anything or if I will even notice?

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FastHeads is doing the head for me. And he cleared up a few other questions i had. He said the stock CPR is 11.0:1 and recommended a higher comp. So i can either go with my 11.5:1 or he offered a wiseco 12.5:1 and oem gaskets for $220.

Now to decide if i want to up the cpr. Anybody want to throw in their 2 cents? Yea or neh?

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I went to 13:1 on my klx 450 and it really woke it up. I have to use 93 octane exclusively, but its easy to get around here. I do notice that there is now zero warning when I am doing technical trails and I let the idle go too low while going up a hill or trying to brake on a steep decent. It will just straight die. It has made me a little better about clutch control though. Other than that I see zero draw backs with higher compression.

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I have 11.5:1 wiseco in my 450x, throttle response is a bit smoother, it's good for dual sport rides, doesn't make pinging noise with lower octane fuel when no other available

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FastHeads is doing the head for me. And he cleared up a few other questions i had. He said the stock CPR is 11.0:1 and recommended a higher comp. So i can either go with my 11.5:1 or he offered a wiseco 12.5:1 and oem gaskets for $220.

Now to decide if i want to up the cpr. Anybody want to throw in their 2 cents? Yea or neh?

Stock CR is 12.0:1...not 11.0:1. Stay away from Wiseco...go with JE.

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Retail manager at JE?

 Ha! Not quite...besides both Wiseco and JE are owned by the same parent company...JE are much higher quality and better design for the same cost.

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