How much compression should it have ?

Started by debatethis, February 12, 2006, 01:35:09 AM

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debatethis

February 12, 2006, 01:35:09 AM
What kind of compression should a Honda CRF 450 motor have in it ?

Thanks
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TurboBanshee_kid

#1
February 12, 2006, 01:37:17 AM
Call honda. www.honda.com
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o4250

#2
February 12, 2006, 01:53:30 AM
A lot.

2006YFZ450

#3
February 12, 2006, 12:48:38 PM
It should have......12.0:1 ;)
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ppark350se

#4
February 13, 2006, 01:19:16 AM
Quote from: 2006YFZ450 on February 12, 2006, 12:48:38 PM
It should have......12.0:1 ;)

hey there smartie pants thats the compression ratio. not the compression he wll see on a compression test. it would be in psi.  i would firgure around 120psi but thats just my guess.
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greenmachine

#5
February 15, 2006, 02:25:41 AM
120-130 is pretty good.

Chuck_Norris

#6
February 17, 2006, 04:48:31 PM
Quote from: ppark350se on February 13, 2006, 01:19:16 AM
Quote from: 2006YFZ450 on February 12, 2006, 12:48:38 PM
It should have......12.0:1 ;)

hey there smartie pants thats the compression ratio. not the compression he wll see on a compression test. it would be in psi.  i would firgure around 120psi but thats just my guess.
divide the PSI number from the compression test  by 15 and that is your compression ratio. that will get you close.

Toomey

#7
February 20, 2006, 12:30:01 AM
Quote from: Chuck_Norris on February 17, 2006, 04:48:31 PM
Quote from: ppark350se on February 13, 2006, 01:19:16 AM
Quote from: 2006YFZ450 on February 12, 2006, 12:48:38 PM
It should have......12.0:1 ;)

hey there smartie pants thats the compression ratio. not the compression he wll see on a compression test. it would be in psi.  i would firgure around 120psi but thats just my guess.
divide the PSI number from the compression test  by 15 and that is your compression ratio. that will get you close.

I don't know about that.  That'll work when it's new, but after it wears and the compression goes down, that won't really work anymore.  The ratio will always be the same.  That's the volume of the cylinder and head when the piston is at BDC, compared to the volume when it's at TDC.  How much compression a motor has changes as it wears or gets rebuilt.  Go to www.thumpertalk.com though for an answer.  120 seems low to me?  2 stroke MX bikes will see 200 often.  I'm not sure if 4 strokes just don't need that kinda compression to run awesome.
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debatethis

#8
February 20, 2006, 03:41:41 PM
That puts it at 12, Thanks Chuck
The world is filled with hypocrites and martyrs....the difference is one has the nerve to stand tall against injustice while the other uses injustice to stand tall

"I don't trust anything that bleeds for 4 days and doesn't die "

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